Postmenopausal Breast Cancer Risk Research Articles

Body mass index and breast cancer risk in premenopausal and postmenopausal East Asian women: a pooled analysis of 13 cohort studies.

It has been suggested that the association between body mass index and breast cancer risk differs between Asian women and Western women. We aimed to assess the associations between body mass index and breast cancer incidence in East Asian women. Pooled analyses were performed using individual participant data of 319,189 women from 13 cohort studies in Japan, Korea, and China. Participants' height and weight were obtained by measurement or self-reports at cohort baseline. Breast cancer was defined as code C50.0-C50.9 according to the International Classification. Using a Cox proportional hazards model, hazard ratios of breast cancer were estimated for each body mass index category, with the reference group set as the group with a body mass index of 21 to < 23 kg/m2. The hazard ratio for a 5kg/m2 increase in body mass index was also calculated. During a mean 16.6 years of follow-up, 4819 women developed breast cancer. Similar to Westerners, a steady increase in breast cancer risk with increasing body mass index was observed in postmenopausal women, but the slope of the risk increase appeared to slow at a body mass index of 26-28 kg/m2. In premenopausal women, the inverse association seen in Westerners was not observed. The risk of developing breast cancer after 50 years of age increased slightly with increasing body mass index, which was more pronounced in the older birth cohort. There was no significant association between body mass index and the risk of developing breast cancer before 50 years of age, but the risk estimates changed from positive to negative as the birth cohort got younger. In East Asia, the role of body mass index in breast cancer in premenopausal women may be changing along with the increase in obesity and breast cancer. The increased risk of postmenopausal breast cancer with a higher body mass index was as robust as that of Western women.

Abstract 4135985: Association of Plasma Cystatin-C with Cancer Risk in Individuals with and without Cardiovascular and Chronic Kidney Disease: An Atherosclerosis Risk in Communities (ARIC) Study

Background: While previous studies suggested a relationship between circulating Cystatin-C (Cys-C), a cysteine protease inhibitor involved in regulating tissue inflammation and a renal filtration marker, and both cancer and CVD, they often lacked long-term follow-up or did not account for the impact of CVD on the relationship between Cys-C and cancer. Methods: We included participants from the Atherosclerosis Risk in Communities (ARIC) study followed from visit 2 (1990-1992) through 2015. Plasma Cys-C level was measured by SomaScan. Other renal filtration markers beta-2 microglobulin (B2M) and beta-trace protein (BTP) were used to compare their cancer association with Cys-C. Incident cancer was ascertained by state cancer registry linkage supplemented with medical records. After adjusting for age, sex, race, and study center, adjusted hazard ratios (aHR) of total and site-specific cancers were estimated using Cox proportional hazards regression stratified by baseline chronic kidney disease (CKD) and CVD status. Results: Among 10,869 individuals (median age of 56.9 years, 55% female, 25% Black, 74% White), 3352 incident cancers were ascertained over a median follow-up of 22.9 years. Among 9585 individuals with no history of CKD or CVD, higher Cys-C was significantly associated with a higher risk of total (aHR 1.22, 95%CI 1.02-1.46), bladder, lung, colorectal, and hematologic malignancies. Among 1,050 individuals with CVD, but not CKD, Cys-C level was not associated with total cancer (aHR 1.22, 95%CI 0.74-2.01), but was significantly inversely associated with colorectal (aHR 0.19, 95%CI 0.05-0.76) and positively associated with post-menopausal breast (aHR 4.52, 95%CI 1.05-19.40) cancer risk. In individuals with CKD but not CVD, Cys-C was negatively associated with bladder (HR 0.08, 95%CI 0.0-0.77) and lung (0.23, 95%CI 0.06-0.82) cancers. Lastly, those with both CKD and CVD showed higher hematopoietic and lymphatic cancer with higher Cys-C (HR 4.68, 95%CI 1.32-16.60). Similar patterns were observed for B2M and BTP proteins. Conclusions: Our study highlights the intricate relationship between various renal filtration markers and cancer risk. It suggests that they may play a significant role in cancer development among the general population and CVD patients but not CKD patients. Further research should explore the biological mechanism underlying these associations with even more CKD cases to refine risk estimates. Funding: NHLBI, NCI, NPCR

Menopausal hormone therapy and incidence, mortality, and survival of breast cancer subtypes: a prospective cohort study

BackgroundMenopausal hormone therapy (MHT) is associated with an increased risk of postmenopausal breast cancer, predominantly the luminal A-like subtype. The impact of MHT on deaths from breast cancer subtypes is less understood. This study aimed to explore associations between MHT use and the incidence, mortality, and survival of intrinsic-like breast cancer subtypes.MethodsData from 160,881 participants with self-reported MHT use from the prospective Norwegian Women and Cancer Study were analyzed. Among them, 7,844 incident breast cancer cases, and 721 breast cancer-specific deaths occurred. Cox proportional hazard regression was performed to calculate hazard ratios (HRs) with 95% confidence intervals (CIs) for the association between MHT use and the incidence, mortality, and survival of breast cancer subtypes.ResultsMHT use was associated with increased risk of overall, luminal A-like, and luminal B-like breast cancer, with respective HRs of 1.44 (95% CI 1.36–1.52), 1.41 (95% CI 1.31–1.52), and 1.23 (95% CI 1.09–1.40) among current estrogen-progestin therapy (EPT) users compared with never users. The risk increased by 4%, 4%, and 2% per year of EPT use for overall, luminal A-like, and luminal B-like breast cancers, respectively. MHT use was also associated with increased risk of overall and luminal A-like breast cancer mortality, with HRs 1.61% (95% CI 1.36–1.91) and 2.15% (95% CI 1.51–3.05) increased risk among current EPT users compared with non-users. Among patients with breast cancer, pre-diagnostic MHT use was not associated with worse survival from overall breast cancer but was inversely associated with survival from triple-negative breast cancer (TNBC; HR death 0.41; 95% CI 0.24–0.73 among current users). Results varied significantly according to tumor subtype (pheterogeneity = 0.02).ConclusionsOur study suggests that MHT use increases the risk of incident and fatal overall and luminal A-like, and incident luminal B-like breast cancer but does not decrease overall survival among patients with breast cancer. Further research is needed to elucidate the mechanisms underlying MHT use and breast cancer lethality, and to explore whether MHT use among patients with TNBC is indeed free from harm.

Breast cancer in women with previous gestational diabetes: a nationwide register-based cohort study

BackgroundGestational diabetes mellitus (GDM) is a common pregnancy complication characterized by insulin resistance. A link has been suggested between insulin resistance and breast cancer, which is the most common cancer in women. Hence, women with previous GDM may be at increased risk of developing breast cancer, yet, the existing evidence is conflicting. This study explored the association between GDM and incident breast cancer, including age at cancer diagnosis. Additionally, we investigated the potential impact of severity of insulin resistance during pregnancy and of subsequent diabetes development on the breast cancer risk.MethodsWe conducted a nationwide, register-based cohort study including all women giving birth in Denmark from 1997 to 2018. We defined GDM and breast cancer based on ICD-10 codes. Premenopausal and postmenopausal breast cancer was pragmatically defined as age at outcome < 50 years and ≥ 50 years, respectively. A proxy for severity of insulin resistance during pregnancy was based on insulin treatment; subsequent diabetes was defined as presence of ICD-10 codes and/or antidiabetic medication after pregnancy. The statistical analyses included Cox regression, logistic regression and t-test.ResultsOf 708,121 women, 3.4% had GDM. The median follow-up period was 11.9 years (range 0-21.9). The overall breast cancer risk was comparable in women with and without previous GDM (adjusted hazard ratio 0.96 [95% CI 0.83–1.12]). Premenopausal and postmenopausal breast cancer risk also did not differ; however, women with previous GDM had a breast cancer diagnosis at younger age (42.6 vs. 43.5 years, p-value 0.01). All-cause mortality was similar regardless of GDM history. Severity of insulin resistance during pregnancy and subsequent diabetes did not affect breast cancer risk.ConclusionsThis large, population-based cohort study showed no higher risk of incident breast cancer in women with previous GDM compared to women without previous GDM after a median of almost 12 years of follow-up. This was evident irrespective of menopausal state. The breast cancer risk was not influenced by the severity of insulin resistance during pregnancy and by subsequent diabetes development. Regardless of GDM history, attention towards prevention, early detection and treatment of breast cancer should be prioritized.

Childhood-to-adulthood body size trajectory and cancer risk: a prospective cohort study

Abstract Background While excess weight in adulthood and childhood has been associated with increased cancer risk, the link between childhood-to-adulthood body size trajectories and cancer risk requires further investigation. Methods We used data from the UK Biobank, a prospective population-based cohort study. The main exposure was childhood-to-adulthood body size trajectory, constructed from self-reported body at age 10 (categories: thinner, average, and plumper than average) and measured body mass index (BMI) at recruitment (normal weight, overweight, and obese). Primary outcome was obesity-related cancer (13 different cancer types). Results During a median follow-up of 11.7 years, 21,289 participants developed obesity-related cancers. Having a larger body size at age 10 was strongly associated with being overweight or obese in adulthood. Compared to participants with average childhood to normal adulthood body size trajectory, all trajectories ending in overweight or obesity in adulthood were strongly associated with an increased risk of obesity-related cancers. The strength of the association was mostly determined by adulthood BMI, and similar patterns were observed for colorectal, endometrial, kidney, pancreatic and esophageal cancer. However, a larger body size in childhood was associated with a lower risk of postmenopausal breast cancer. Conclusions Although a larger body size in childhood predisposes to overweight and obesity in adulthood, it does not necessarily predispose to an increased obesity-related cancer risk if measures to maintain a healthy weight are taken in adulthood. Key messages • While larger body size in childhood predisposes individuals to overweight and obesity in adulthood, maintaining a healthy weight in adulthood may help mitigate the risk of obesity-related cancers. • Our findings highlight the importance of preventing and reducing overweight and obesity in adulthood for primary cancer prevention.

Trajectories in mammographic breast screening participation in middle-age overweight and obese women: A retrospective cohort study using linked data

ObjectivesDespite the established benefits and availability of mammographic breast screening, participation rates remain suboptimal. Women with higher BMIs may not screen regularly, despite being at increased risk of postmenopausal breast cancer and worse outcomes. This study investigated the association between prospective changes in BMI and longitudinal adherence to mammographic screening among women with overweight or obesity. MethodsRetrospective cohort study of women (N = 2822) participating in the Australian Longitudinal Study on Women's Health with an average follow-up of 20 years, with screening participation enumerated via BreastScreen NSW, Australia clinical records over the period 1996–2016. Association between BMI and subsequent adherence to screening was investigated in a series of marginal structural models, incorporating a time variant/invariant socio-demographic, clinical, and health behaviour confounders. Models were also stratified by a proxy measure of socio-economic status (education). ResultsParticipants with overweight/obesity were less adherent to mammography screening, compared to healthy/underweight participants (OR=1.29, 95 % CI=1.07, 1.55). The association between overweight/obesity and non-adherence was higher among those who ever had private health insurance (OR=1.30, 95 % CI=1.05, 1.61) compared to those who never had private health insurance and among those with lower educational background (OR=1.38, 95 % CI=1.08, 1.75) compared to those with higher educational background. ConclusionsLong-term impacts on screening participation exist among women with higher BMI, who are less likely to participate in routinely organised breast screening. Women with a higher BMI should be a focus of efforts to improve breast screening participation, particularly given their increased risk of breast cancer and association of higher BMI with worse breast cancer outcomes among older women.

Association between body mass index combined with high-sensitivity C-reactive protein and the risk of postmenopausal breast cancer: A prospective cohort study.

The present study aimed to assess the risk of postmenopausal breast cancer in women based on a combination of body mass index (BMI) and high-sensitivity C-reactive protein (hs-CRP) levels. A total of 20,400 participants were investigated as part of the 'Kailuan Study' clinical trial. Participants were classified into four groups based on BMI (BMI ≥24 or <24 kg/m2) and hs-CRP level (hs-CRP ≥3 or <3 mg/l). Cox proportional hazards models were used to evaluate the association between the combination of BMI and hs-CRP and the risk of postmenopausal breast cancer. A total of 19,540 participants met the inclusion criteria. The median follow-up time was 14.97 years, with a cumulative follow-up period of 283,599.43 person-years. Among the participants, 269 individuals were diagnosed with postmenopausal breast cancer. Individuals with a high BMI (BMI ≥24 kg/m2) and a high hs-CRP level (hs-CRP ≥3 mg/) had a greater risk of postmenopausal breast cancer compared with individuals with a low BMI (BMI <24 kg/m2) and a low hs-CRP level (<3 mg/l) (hazard ratio, 1.75; 95% confidence interval, 1.25-2.47). The sensitivity analysis showed findings consistent with the primary results. In conclusion, the combination of high BMI and high hs-CRP level is associated with an increased risk of postmenopausal breast cancer. The present study is part of the Kailuan Study. Trial registration number: ChiCTRTNCR11001489 (Chinese Clinical Trial Registry, https://www.chictr.org.cn/showproj.html?proj=8050). Date of registration: 19/07/2015.

Carcinogenic industrial air pollution and postmenopausal breast cancer risk in the National Institutes of Health AARP Diet and Health Study

BackgroundChemicals emitted from industrial facilities include known or suspected mammary carcinogens and endocrine disruptors, but epidemiologic studies are limited. We evaluated associations between air emissions of multiple carcinogenic chemicals and postmenopausal breast cancer risk in a large prospective U.S. cohort. MethodsWe used the U.S. Environmental Protection Agency’s Toxics Release Inventory to estimate historical airborne emissions (1987–1995) of 19 known and probable carcinogens for participants enrolled (1995–1996) in the NIH-AARP Diet and Health Study. Among 170,402 women, 15,124 breast cancers were diagnosed through 2018. We constructed inverse distance- and wind-weighted average emissions metrics within 1, 2, 5, and 10 km of the enrollment address for each chemical. We estimated multivariable adjusted HRs and 95 % CIs for categories (quartiles, tertiles, medians) of each chemical in association with breast cancer overall and separately by type (invasive, ductal carcinoma in situ) and estrogen receptor (ER) status. ResultsWe observed an association between benzene emissions and breast cancer risk that was strongest at 1 km (HRQ4 vs. non-exposed = 2.06, 95 %CI: 1.34–3.17; p-trend = 0.001). The magnitude of the association weakened with increasing distance (2 km HRQ4 vs. non-exposed = 1.17, 95 %CI=0.92–1.49; p-trend = 0.19; 5 km HRQ4 vs. non-exposed = 1.05, 95 %CI=0.94–1.16; p-trend = 0.37; 10 km HRQ4 vs. non-exposed = 0.95, 95 %CI=0.89–1.02; p-trend = 0.19) and appeared to be most relevant for invasive rather than intraductal disease. Overall risk was also elevated for vinyl chloride at 5 km (HR≥median vs. non-exposed = 1.20, 95 %CI=1.01–1.43; p-trend = 0.04), but not 2 km or 10 km. We observed suggestive associations for asbestos, trichloroethylene, and styrene in different subgroup analyses, but risk patterns were not clear across distances. Associations with other chemicals were generally null, with limited evidence of heterogeneity by disease type or ER status. ConclusionsAn increased risk of breast cancer associated with relatively high levels of industrial benzene emissions warrants additional study, particularly among participants with diverse sociodemographic characteristics that live in areas with higher density of industrial facilities.

Glucagon-Like Peptide 1 Receptor Agonists and 13 Obesity-Associated Cancers in Patients With Type 2 Diabetes

Thirteen human malignant neoplasms have been identified as obesity-associated cancers (OACs), ie, the presence of excess body fat is associated with increased risk of developing cancer and worse prognosis in patients with these specific tumors. The glucagon-like peptide receptor agonist (GLP-1RA) class of pharmaceuticals are effective agents for the treatment of type 2 diabetes (T2D) and for achieving weight loss, but the association of GLP-1RAs with the incident risk of 13 OACs is unclear. To compare the incident risk of each of the 13 OACs in patients with T2D who were prescribed GLP-1RAs vs insulins or metformin. This retrospective cohort study was based on a nationwide multicenter database of electronic health records (EHRs) of 113 million US patients. The study population included 1 651 452 patients with T2D who had no prior diagnosis of OACs and were prescribed GLP-1RAs, insulins, or metformin during March 2005 to November 2018. Data analysis was conducted on April 26, 2024. Prescription of GLP-1RAs, insulins, or metformin. Incident (first-time) diagnosis of each of the 13 OACs occurring during a 15-year follow-up after the exposure was examined using Cox proportional hazard and Kaplan-Meier survival analyses with censoring applied. Hazard ratios (HRs), cumulative incidences, and 95% CIs were calculated. All models were adjusted for confounders at baseline by propensity-score matching baseline covariates. In the study population of 1 651 452 patients with T2D (mean [SD] age, 59.8 [15.1] years; 827 873 [50.1%] male and 775 687 [47.0%] female participants; 5780 [0.4%] American Indian or Alaska Native, 65 893 [4.0%] Asian, 281 242 [17.0%] Black, 13 707 [0.8%] Native Hawaiian or Other Pacific Islander, and 1 000 780 [60.6%] White participants), GLP-1RAs compared with insulin were associated with a significant risk reduction in 10 of 13 OACs, including in gallbladder cancer (HR, 0.35; 95% CI, 0.15-0.83), meningioma (HR, 0.37; 95% CI, 0.18-0.74), pancreatic cancer (HR, 0.41; 95% CI, 0.33-0.50), hepatocellular carcinoma (HR, 0.47; 95% CI, 0.36-0.61), ovarian cancer (HR, 0.52; 95% CI, 0.03-0.74), colorectal cancer (HR, 0.54; 95% CI, 0.46-0.64), multiple myeloma (HR, 0.59; 95% CI, 0.44-0.77), esophageal cancer (HR, 0.60; 95% CI, 0.42-0.86), endometrial cancer (HR, 0.74; 95% CI, 0.60-0.91), and kidney cancer (HR, 0.76; 95% CI, 0.64-0.91). Although not statistically significant, the HR for stomach cancer was less than 1 among patients who took GLP-1RAs compared with those who took insulin (HR, 0.73; 95% CI, 0.51-1.03). GLP-1RAs were not associated with a reduced risk of postmenopausal breast cancer or thyroid cancer. Of those cancers that showed a decreased risk among patients taking GLP-1RAs compared with those taking insulin, HRs for patients taking GLP-1RAs vs those taking metformin for colorectal and gallbladder cancer were less than 1, but the risk reduction was not statistically significant. Compared with metformin, GLP-1RAs were not associated with a decreased risk of any cancers, but were associated with an increased risk of kidney cancer (HR, 1.54; 95% CI, 1.27-1.87). In this study, GLP-1RAs were associated with lower risks of specific types of OACs compared with insulins or metformin in patients with T2D. These findings provide preliminary evidence of the potential benefit of GLP-1RAs for cancer prevention in high-risk populations and support further preclinical and clinical studies for the prevention of certain OACs.

A Mediation Analysis of Obesity and Adiponectin Association with Postmenopausal Breast Cancer Risk: A Nested Cohort Study in the International Breast Cancer Intervention Study II (IBIS-II) Prevention Trial.

Obesity is a risk factor for postmenopausal breast cancer (BC), and evidence suggests a role for adiponectin in the relationship between obesity and BC. We investigated whether adiponectin or other biomarkers mediate the effect of body mass index (BMI) on postmenopausal BC risk in a cohort study nested in the IBIS-II Prevention Trial. We measured adiponectin, leptin, IGF-I, IGFBP-1, high-sensitivity C-reactive protein, glycemia, insulin, HOMA-IR index, and SHBG in baseline and 12-month serum samples from 123 cases and 302 matched controls in the placebo arm of the IBIS-II Prevention trial. We conducted the main mediation analysis considering baseline BMI as an exposure and the 12-month adiponectin increase as a mediator after adjustment for the Tyrer-Cuzick score and the lipid-lowering medications/supplements use. In the multivariable Cox model, both the 12-month adiponectin increase (HR, 0.60; 95%CI, 0.36-1.00) and BMI were associated with BC risk (HR, 1.05; 95%CI, 1.00-1.09), with a 40% reduction in women with a 12-month increase in adiponectin. A significantly higher cumulative hazard of BC events was observed in obese women (BMI > 30) with decreased adiponectin (p = 0.0087). No mediating effect of the adiponectin increase on the total effect of BMI on BC risk was observed (natural indirect effect: HR, 1.00; 95%CI, 0.98-1.02). Raising adiponectin levels might be an attractive target for postmenopausal BC prevention.

Abstract PO5-14-01: Weight loss and omega-3 polyunsaturated fatty acid intervention in overweight and obese peri- and postmenopausal women with increased breast cancer risk modifies the gut microbiome and is associated with circulating biomarkers

Abstract Background: Obesity-associated gut microbiome dysbiosis is thought to increase risk for postmenopausal breast cancer through alteration of estrogen metabolism and an increase in pro-inflammatory microbe abundance. Many studies have reported an increase in the Firmicutes/Bacteroidetes phyla ratio as a biomarker of obesity and is associated with adverse metabolic outcomes. Marine omega-3 eicosapentaenoic (EPA) and docosahexaenoic (DHA) fatty acids are thought to have favorable metabolic and inflammation resolving properties resulting in reduced risk for several epithelial cancers. One possible mechanism is the effect of EPA and DHA on the gut microbiome. We assessed the effect of weight loss and/or omega-3 supplementation on the gut microbiome and circulating molecular breast cancer risk factors. Methods: 46 peri/postmenopausal overweight and obese women at increased risk for breast cancer were enrolled into a weight-loss intervention and after 2 weeks randomized to 3.25 g/day combined EPA and DHA or placebo (PMC8416797). Fecal samples were collected at 0, 2-weeks and 6-months, with matched fecal samples for all timepoints available for 26 patients. Fecal samples at 6-months were available for 34 patients. 12M read depth metagenomic sequencing was performed on DNA isolated from feces to determine shifts in the gut microbiome. Fasting and non-fasting blood was also collected for circulating biomarker analysis. Body composition by DXA scan were also performed at baseline and 6-month time points. Results: Mean baseline BMI was 32 kg/m2. There was no significant difference between arms in age, baseline BMI, % body fat, or baseline Firmicutes/Bacteroidetes ratio. We identified gut microbiota species (A. hadrus and P. faecium) that correlated with metabolic parameters (% body fat, adiponectin/leptin ratio, and fasting insulin), species (P. dorei and B. ovatus) that correlated with estradiol levels, and mucin-degrading species (D. formicigenerans and R. gnavus) whose abundance correlated with inflammation (as measured by circulating monocyte-chemoattractant protein 1 (MCP-1)). Median 6-month weight change for all randomized subjects was -10% from baseline. Favorable change in the Firmicutes/Bacteroidetes ratio was associated both with the degree of weight loss and with omega-3 supplementation, although significant species modification differed between weight loss and omega-3 PUFA groups. Women with both &amp;gt;10% weight loss and omega-3 supplementation had a significantly reduced Firmicutes abundance and lower Firmicute/Bacteroidetes ratio than other groups. Species abundance shifts appear to differ between weight loss and omega-3 supplementation with 3 species modified by weight loss and 12 species shifted by omega-3 PUFA administration. Omega-3 PUFA supplementation significantly reduced proportional abundance of Dorea formicigenerans, which was a microbe associated with inflammation. Conclusions: Omega-3 supplementation at 3.25 g/day compared to placebo had a greater net effect on changing the gut microbiome in overweight and obese women at increased risk for breast cancer undergoing a weight loss intervention. Change in the gut microbiome may serve as a useful response biomarker in Phase II prevention trials of omega-3 fatty acid and weight loss. Citation Format: Katherine L. Cook, Erin Giles, Amy Kreutzjans, Shahid Umar, Christie Befort, Bruce Kimler, Stephen Hursting, Carol Fabian. Weight loss and omega-3 polyunsaturated fatty acid intervention in overweight and obese peri- and postmenopausal women with increased breast cancer risk modifies the gut microbiome and is associated with circulating biomarkers [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-14-01.

A low-glucose eating pattern is associated with improvements in glycemic variability among women at risk for postmenopausal breast cancer: an exploratory analysis.

High glycemic variability (GV) is a biomarker of cancer risk, even in the absence of diabetes. The emerging concept of chrononutrition suggests that modifying meal timing can favorably impact metabolic risk factors linked to diet-related chronic disease, including breast cancer. Here, we examined the potential of eating when glucose levels are near personalized fasting thresholds (low-glucose eating, LGE), a novel form of timed-eating, to reduce GV in women without diabetes, who are at risk for postmenopausal breast cancer. In this exploratory analysis of our 16-week weight loss randomized controlled trial, we included 17 non-Hispanic, white, postmenopausal women (average age = 60.7 ± 5.8 years, BMI = 34.5 ± 6.1 kg/m2, HbA1c = 5.7 ± 0.3%). Participants were those who, as part of the parent study, provided 3-7 days of blinded, continuous glucose monitoring data and image-assisted, timestamped food records at weeks 0 and 16. Pearson's correlation and multivariate regression were used to assess associations between LGE and GV, controlling for concurrent weight changes. Increases in LGE were associated with multiple unfavorable measures of GV including reductions in CGM glucose mean, CONGA, LI, J-Index, HBGI, ADDR, and time spent in a severe GV pattern (r = -0.81 to -0.49; ps < 0.044) and with increases in favorable measures of GV including M-value and LBGI (r = 0.59, 0.62; ps < 0.013). These associations remained significant after adjusting for weight changes. Low-glucose eating is associated with improvements in glycemic variability, independent of concurrent weight reductions, suggesting it may be beneficial for GV-related disease prevention. Further research in a larger, more diverse sample with poor metabolic health is warranted.Clinical trial registration: ClinicalTrials.gov, NCT03546972.

Multi-Trait Body Shape Phenotypes and Breast Cancer Risk in Postmenopausal Women: A Causal Mediation Analysis in the UK Biobank Cohort

Body shape phenotypes combining multiple anthropometric traits have been linked to postmenopausal breast cancer (BC). However, underlying biological pathways remain poorly understood. This study investigated to what extent the associations of body shapes with postmenopausal BC risk is mediated by biochemical markers. The study included 176,686 postmenopausal women from UK Biobank. Four body shape phenotypes were derived from principal component (PC) analysis of height, weight, body mass index, waist and hip circumferences, and waist-to-hip ratio (WHR). The four-way decomposition of the total effect was used to estimate mediation and interaction effects simultaneously as well as the mediated proportions. After 10.9 years median follow-up, 6,396 incident postmenopausal BC were diagnosed. There was strong evidence of positive associations between PC1 (general obesity) and PC2 (tall, low WHR), and BC risk. The association of PC1 with BC risk was positively mediated by testosterone and negatively by insulin-like growth factor-1 (IGF-1), with the overall proportion mediated (sum of the mediated interaction and pure indirect effect (PIE)) accounting for 11.4% (95% confidence intervals: 5.1 to 17.8%) and -12.2% (-20.5% to -4.0%) of the total effect, respectively. Small proportions of the association between PC2 and BC were mediated by IGF-1 (PIE: 2.8% (0.6 to 4.9%)), and sex hormone-binding globulin (SHBG) (PIE: -6.1% (-10.9% to -1.3%)). Our findings are consistent with differential pathways linking different body shapes with BC risk, with a suggestive mediation through testosterone and IGF-1 in the relationship of a generally obese body shape and BC risk, while IGF-1 and SHBG may mediate a tall/lean body shape-BC risk association.

Abstract LB149: Metabolic syndrome and obesity-related cancer risk and survival: An umbrella review

Abstract Background: Recent evidence suggests that metabolic syndrome (MetS) may be a potential risk factor for obesity-related cancer (ORC) owing to shared risk factors like physical inactivity, hyperglycemia, insulin resistance, gut microbiome dysfunction, and inflammation. We conducted an umbrella review of systematic reviews with meta-analysis to synthesize the evidence on the association between MetS and ORC incidence and survival. Methods: The study protocol was registered with PROSPERO (CRD42021230899). Searches in five databases (Medline, Embase, CINAHL, Cochrane Library, and Scopus) retrieved 2,524 systematic reviews with meta-analyses (SRMA) after duplicates were removed. SRMA were eligible if they evaluated MetS with ORC incidence or survival, were conducted in an adult population (≥18 years), and included the pre-defined study-specific data. Using Covidence, two reviewers independently screened titles and abstracts (2,524) and then reviewed full text (41), selecting 23 SRMAs for inclusion. Data extraction was then completed independently by two reviewers. The outcomes were pooled using a random-effects model with the package “meta” in R. Sub-group analyses were conducted for a priori chosen factors, as outlined in the protocol. SRMA were appraised using the AMSTAR 2 criteria. Results: 23 SRMA published between 2001 and 2023 met our inclusion criteria, comprising a total of 112 studies, ~52,543,335 total individuals, and ~355,808 ORC cases. After pooled analyses, MetS was associated with a statistically significant 10% increased risk of ORC [RR(95% CI): 1.10(1.06-1.14)]. MetS was also statistically significantly associated with poorer ORC-specific survival [RR(95% CI): 1.10(1.02-1.18)], though there was no association between MetS and overall survival [RR(95% CI): 1.04(0.97-1.11)]. When stratified by sex, both male and female individuals with MetS had a statistically significant higher risk of ORC [RR(95% CI): 1.12(1.06-1.17), 1.10(1.01-1.19), respectively]. When stratified by cancer site, individuals with MetS demonstrated a higher risk of colorectal cancer [RR(95% CI): 1.12(1.06-1.18)]. We also observed suggestive associations between MetS and liver, pancreatic, and postmenopausal breast cancer risk, but these were not statistically significant [RR(95% CI): 1.20(1.00-1.45), 1.20(0.96-1.50), 1.12(0.99-1.27), respectively]. All associations were supported by “critically low” quality evidence according to the AMSTAR2 criteria. This was primarily because these SRMAs either did not follow a pre-specified written and published protocol, or did not provide a list of all potentially relevant studies that were read in full-text form but excluded from the review. Conclusions: These results emphasize the important role that MetS may play in the development of ORC as well as in the survival of patients with ORC. Conducting high-quality reviews is needed to increase the certainty of evidence, reduce potential bias, and improve knowledge in this field. Citation Format: Maci Winn, Prasoona Karra, Ryzen Benson, Svenja Pauleck, Nathorn Chaiyakunapruk, Win Khaing, Tallie Casucci, Mary M. McFarland, Siwen Hu-Lieskovan, Michelle Litchman, Yizhe Xu, Mary Playdon, Sheetal Hardikar. Metabolic syndrome and obesity-related cancer risk and survival: An umbrella review [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB149.

Higher number of steps is related to lower endogenous progesterone but not estradiol levels in women.

Sex steroid hormones are important not only for reproduction but also for many aspects of women's health, including the risk of breast cancer. Physical activity has been shown to influence sex hormone levels in women. This study aimed to investigate a relationship between the average daily number of steps and the sex hormone (estradiol and progesterone) levels in premenopausal women. Data were collected from 85 healthy, urban women of reproductive age who performed at least 180 minutes/week of moderate physical activity for two complete menstrual cycles. Physical activity was measured using wrist bands. Estradiol and progesterone concentrations were measured in daily-collected saliva samples in the second menstrual cycle. There was a significant negative association between the average number of steps taken daily and salivary progesterone levels after adjusting for potential confounding factors (age, BMI). Women who took more than 10,000 steps a day had significantly lower progesterone levels compared to women who took less than 10,000 steps. The association between physical activity and estradiol levels was statistically insignificant. Our results indicate that taking at least 10,000 steps a day reduces progesterone levels, but this intensity of physical activity may not be high enough to affect estradiol levels. Daily step tracking is a valuable element of health promotion, but currently recommended levels of physical activity may not be high enough for healthy premenopausal women to significantly reduce both sex hormone levels and thus their risk of postmenopausal breast cancer.

New role of fat-free mass in cancer risk linked with genetic predisposition

Cancer risk is associated with the widely debated measure body mass index (BMI). Fat mass and fat-free mass measurements from bioelectrical impedance may further clarify this association. The UK Biobank is a rare resource in which bioelectrical impedance and BMI data was collected on ~ 500,000 individuals. Using this dataset, a comprehensive analysis using regression, principal component and genome-wide genetic association, provided multiple levels of evidence that increasing whole body fat (WBFM) and fat-free mass (WBFFM) are both associated with increased post-menopausal breast cancer risk, and colorectal cancer risk in men. WBFM was inversely associated with prostate cancer. We also identified rs615029[T] and rs1485995[G] as associated in independent analyses with both PMBC (p = 1.56E–17 and 1.78E–11) and WBFFM (p = 2.88E–08 and 8.24E–12), highlighting splice variants of the intriguing long non-coding RNA CUPID1 (LINC01488) as a potential link between PMBC risk and fat-free mass.

Infertility and risk of postmenopausal breast cancer in the women's health initiative.

Although infertility (i.e., failure to conceive after ≥ 12months of trying) is strongly correlated with established breast cancer risk factors (e.g., nulliparity, number of pregnancies, and age at first pregnancy), its association with breast cancer incidence is not fully understood. Previous studies were primarily small clinic-based or registry studies with short follow-up and predominantly focused on premenopausal breast cancer. The objective of this study was to assess the relationship between infertility and postmenopausal breast cancer risk among participants in the Women's Health Initiative (analytic sample = 131,784; > 25years of follow-up). At study entry, participants were asked about their pregnancy history, infertility history, and diagnosed reasons for infertility. Incident breast cancers were self-reported with adjudication by trained physicians reviewing medical records. Cox proportional hazards models were used to estimate risk of incident postmenopausal breast cancer for women with infertility (overall and specific infertility diagnoses) compared to parous women with no history of infertility. We examined mediation of these associations by parity, age at first term pregnancy, postmenopausal hormone therapy use at baseline, age at menopause, breastfeeding, and oophorectomy. We observed a modest association between infertility (n = 23,406) and risk of postmenopausal breast cancer (HR = 1.07; 95% CI 1.02-1.13). The association was largely mediated by age at first term pregnancy (natural indirect effect: 46.4% mediated, CI 12.2-84.3%). These findings suggest that infertility may be modestly associated with future risk of postmenopausal breast cancer due to age at first pregnancy and highlight the importance of incorporating reproductive history across the life course into breast cancer analyses.

How does weight gain since the age of 18 years affect breast cancer risk in later life? A meta-analysis

Early life factors are important risk factors for breast cancer. The association between weight gain after age 18 and breast cancer risk is inconsistent across previous epidemiologic studies. To evaluate this association, we conducted a meta-analysis according to PRISMA guidelines and the established inclusion criteria. We performed a comprehensive literature search using Medline (Ovid), Embase, Scopus, Cochrane Library, and ClinicalTrials.gov to identify relevant studies published before June 3, 2022. Two reviewers independently reviewed the articles for final inclusion. Seventeen out of 4,725 unique studies met the selection criteria. The quality of studies was assessed using the Newcastle-Ottawa Scale (NOS), and all were of moderate to high quality with NOS scores ranging from 5 to 8. We included 17 studies (11 case-control, 6 cohort) in final analysis. In case-control studies, weight gain after age 18 was associated with an increased risk of breast cancer (odds ratio [OR] = 1.25; 95% CI = 1.07–1.48), when comparing the highest versus the lowest categories of weight gain. Menopausal status was a source of heterogeneity, with weight gain after age 18 associated with an increased risk of breast cancer in postmenopausal women (OR = 1.53; 95% CI = 1.40–1.68), but not in premenopausal women (OR = 1.01; 95% CI = 0.92–1.12). Additionally, a 5 kg increase in weight was positively associated with postmenopausal breast cancer risk (OR = 1.12; 95%CI = 1.05–1.21) in case-control studies. Findings from cohort studies were identical, with a positive association between weight gain after age 18 and breast cancer incidence in postmenopausal women (relative risk [RR] = 1.30; 95% CI = 1.09–1.36), but not in premenopausal women (RR = 1.06; 95% CI = 0.92–1.22). Weight gain after age 18 is a risk factor for postmenopausal breast cancer, highlighting the importance of weight control from early adulthood to reduce the incidence of postmenopausal breast cancer.

Sex-steroid hormones and risk of postmenopausal estrogen receptor-positive breast cancer: a case-cohort analysis.

Sex-steroid hormones are associated with postmenopausal breast cancer but potential confounding from other biological pathways is rarely considered. We estimated risk ratios for sex-steroid hormone biomarkers in relation to postmenopausal estrogen receptor (ER)-positive breast cancer, while accounting for biomarkers from insulin/insulin-like growth factor-signaling and inflammatory pathways. This analysis included 1208 women from a case-cohort study of postmenopausal breast cancer within the Melbourne Collaborative Cohort Study. Weighted Poisson regression with a robust variance estimator was used to estimate risk ratios (RRs) and 95% confidence intervals (CIs) of postmenopausal ER-positive breast cancer, per doubling plasma concentration of progesterone, estrogens, androgens, and sex-hormone binding globulin (SHBG). Analyses included sociodemographic and lifestyle confounders, and other biomarkers identified as potential confounders. Increased risks of postmenopausal ER-positive breast cancer were observed per doubling plasma concentration of progesterone (RR: 1.22, 95% CI 1.03 to 1.44), androstenedione (RR 1.20, 95% CI 0.99 to 1.45), dehydroepiandrosterone (RR: 1.15, 95% CI 1.00 to 1.34), total testosterone (RR: 1.11, 95% CI 0.96 to 1.29), free testosterone (RR: 1.12, 95% CI 0.98 to 1.28), estrone (RR 1.21, 95% CI 0.99 to 1.48), total estradiol (RR 1.19, 95% CI 1.02 to 1.39) and free estradiol (RR 1.22, 95% CI 1.05 to 1.41). A possible decreased risk was observed for SHBG (RR 0.83, 95% CI 0.66 to 1.05). Progesterone, estrogens and androgens likely increase postmenopausal ER-positive breast cancer risk, whereas SHBG may decrease risk. These findings strengthen the causal evidence surrounding the sex-hormone-driven nature of postmenopausal breast cancer.

Abstract B086: Association of breast cancer-relevant DNA repair genes with postmenopausal breast cancer risk in UK Biobank

Abstract Purpose. Several polymorphisms have been described in DNA damage signaling and repair genes and some of the polymorphisms have been implicated in genetic susceptibility to breast cancer. However, there is no consensus result yet for most of these polymorphisms. In this study, we focused on evaluating selected SNPs in BRCA1, BRCA2, ATM, XRCC1, XRCC2, XRCC3, and XPD (ERCC2) genes that have been previously reported to be associated with breast cancer risk and are available in the UK Biobank. Methods. This study included 150,929 postmenopausal women (5,969 with BCa) from UK Biobank, a population-based prospective cohort. Cancer diagnoses were ascertained through the linkage to the UK National Health Service Central Registers. DNA was extracted from blood samples collected from participants at enrollment in UK Biobank. Samples were genotyped using the Applied Biosystems UK BiLEVE Axiom Array or the Applied Biosystems UK Biobank Axiom Array. The positions of markers in the data are in GRCh37 coordinates. SNPs with frequency &amp;lt; 1% in the study population were excluded from analyses. We included the following SNPs in the final analyses: XRCC3-rs861539, BRCA1-rs16942, BRCA1-rs4986852, XRCC1-rs25487, XRCC1-rs25489, XRCC1-rs1799782, XPD (ERCC2)-rs13181, XPD (ERCC2)-rs1799793, XRCC2-rs3218536, ATM-rs1800056, ATM-rs1800057, BRCA2-rs144848, BRCA2-rs4987117, and BRCA2-rs11571833. Information on breast cancer risk factors was collected at baseline. Cox proportional hazards regression models were used to analyze the association between each SNP and breast cancer risk while adjusting for known breast cancer risk factors. The risk estimates were presented as hazard rations (HRs) and their corresponding 95% confidence intervals (CIs). Results. The mean age of the study population at enrollment was 60.1 years (range 40-71 years). Heterozygous carriers of BRCA2-rs11571833 T allele were found to have an increased risk of breast cancer (HR=1.22, 95% CI 1.02, 1.46, p-trend = 0.033) compared to the homozygous carriers of the BRCA2-rs11571833 A allele. No other significant associations between other SNPs and breast cancer risk were found. Conclusions. We found a significant association between SNP BRCA2-rs11571833 and postmenopausal breast cancer risk. Our findings contribute to the existing evidence on the association of high-risk polymorphisms in DNA damage signaling and repair genes with postmenopausal breast cancer risk. Citation Format: Carmen Smotherman, Brian Sprague, Dejana Braithwaite, Huaizhen Qin, Lusine Yaghjyan. Association of breast cancer-relevant DNA repair genes with postmenopausal breast cancer risk in UK Biobank [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Breast Cancer Research; 2023 Oct 19-22; San Diego, California. Philadelphia (PA): AACR; Cancer Res 2024;84(3 Suppl_1):Abstract nr B086.