Risk Factor For Thyroid Cancer Research Articles

Serum Thyroglobulin Improves the Sensitivity of the McGill Thyroid Nodule Score for Well-Differentiated Thyroid Cancer

The McGill Thyroid Nodule Score (MTNS) is a scoring system devised to help physicians to assess the preoperative risk that a thyroid nodule is malignant. It uses 22 different known risk factors for thyroid cancer (radiation exposure, microcalcifications on ultrasound, positive HBME-1 stain on biopsy, etc.) and attributes a percentage risk that the nodule is malignant. Recently, preoperative thyroglobulin (Tg) levels have been shown to correlate with the risk of malignancy. The aim of this study was to incorporate Tg levels into the already established MTNS. This is a retrospective analysis of 184 thyroidectomy patients at the McGill University Thyroid Cancer Center. Patients with preoperative Tg levels were included in the study, and patients with incidental papillary microcarcinoma without extrathyroidal extent on final pathology were excluded. MTNS scores were calculated for all patients. Preoperative Tg levels of 75 ng/mL added one point to the MTNS, and levels of 187.5 ng/mL added two points. The new system is named MTNS+. Malignancy rates were calculated for each MTNS+ score. Patients with a score of 0-1 were <5% at risk of malignancy. The malignancy rate for scores of 2-3 was 14.29%, followed by 28.95% for scores of 4-6, 32.65% for scores of 7-8, 64.86% for scores of 9-11, 71.43% for scores of 12-14, 78.57% for scores of 15-18, and 92.31% for scores of 19-22. All patients (five of five) with an MTNS+ score of 23 or more had a malignant final pathology result. Patients with scores greater than eight had a relative risk of 2.5 [CI 1.79-3.49] of malignancy compared to patients with lower scores. MTNS+ showed good specificity at higher scores, with 89%, 96%, and 100% at scores above 11, 14, and 20 respectively. Compared to MTNS, adding Tg levels did not improve positive predictive values (PPV) or specificity, but improved sensitivity by 7.89% for scores greater than eight, and by up to 10.48% for scores greater than seven. This study shows that adding Tg to the MTNS increases the sensitivity of this scoring system. Moreover, it suggests that a combined scoring system such as the MTNS+ can accurately stratify the risk of well-differentiated malignancy in patients with thyroid nodules.

Thyroid Malignancies in Survivors of Hodgkin Lymphoma

To quantify the incidence of thyroid cancer after Hodgkin lymphoma (HL) and determine disease characteristics, risk factors, and treatment outcomes. Thyroid cancer cases were retrospectively identified from a multi-institutional database of 1981 HL patients treated between 1969 and 2008. Thyroid cancer risk factors were evaluated by a Poisson regression model. With a median follow-up duration of 14.3 years (range, 0-41.2 years), 28 patients (1.4%) developed a thyroid malignancy. The overall incidence rate (expressed as the number of cases per 10,000 person-years) and 10-year cumulative incidence of thyroid cancer were 9.6 and 0.26%, respectively. There were no observed cases of thyroid malignancy in patients who received neck irradiation for HL after age 35 years. Age <20 years at HL diagnosis and female sex were significantly associated with thyroid cancer. The incidence rates of females aged <20 at HL diagnosis in the first 10 years, ≥10 years, ≥15 years, and ≥20 years after treatment were 5, 31, 61, and 75 cases per 10,000 person-years of follow-up, respectively. At a median follow-up of 3.5 years after the thyroid cancer diagnosis, 26 patients (93%) were alive without disease, 1 (4%) was alive with metastatic disease, and 1 (4%) died of metastatic disease, at 6 and 3.6 years after the thyroid cancer diagnosis, respectively. Although HL survivors have an increased risk for thyroid cancer, the overall incidence is low. Routine thyroid cancer screening may benefit females treated at a young age and ≥10 years from HL treatment owing to their higher risk, which increases over time.

Does Increased Body Mass Index Lead to Elevated Thyroid Cancer Risk?

Purpose: Obesity is associated with various diseases including thyroid cancer. The relationship between thyroid nodules and obesity is unclear. In this study, patients with a higher-than-population risk of thyroid cancer whose thyroid fine needle aspiration biopsies were suspicious or indeterminate were divided into groups according to their body mass index and their rate of malignancy was examined. Method: In this study, 214 patients who were operated for indeterminate cytology in 2009-2010 at our clinic were reviewed retrospectively. The patients were divided into 4 groups. Group 1 included 47 patients (BMI 18-24,9 kg/ m2); Group 2 included 67 patients (BMI 25-29,9); Group 3 included 85 patients (BMI 30-39,9); and Group 4 had 15 patients (BMI > 40). Patients were classified as benign and malign based on the postoperative histopathological results. Malignancy rates were recorded for each group and the groups were compared. Results: Based on the histopathological results of the 214 patients included in the study, 70 patients were reported to have thyroid cancer (32.7%). When the patients were divided into groups as benign and malign according to the pathology results, age, BMI, height, fT3, TSH, body fat ratios and WC/HC ratios were found to be similar between groups (p>0.05). fT4 was found to be significantly elevated in the malign group (p<0.05). Conclusion: In this study, malignancy rates increased as the patients' body mass index increased but the difference was not statistically significant (p>0.05). Obesity and increased body mass index may be a risk factor for thyroid cancer.

Physical activity, diabetes, and risk of thyroid cancer: a systematic review and meta-analysis

Thyroid cancer incidence has been increasing more rapidly over time than the occurrence of cancers of other sites, and interest in potential adverse relations of diabetes and lack of physical activity to thyroid cancer risk is accumulating. We conducted a systematic review and meta-analysis of published epidemiologic studies on the relations of physical activity and diabetes to thyroid cancer according to the Meta-analysis of Observational Studies in Epidemiology guidelines. Published studies were identified through a search in MEDLINE and EMBASE. Random-effects models were used to summarize thyroid cancer risk estimates comparing high versus low levels of physical activity, and separately, comparing individuals with diabetes versus those without diabetes. Meta-regression analyses were performed to evaluate potential effect modification by study design and thyroid cancer risk factors. Information was extracted from seven studies of physical activity and thyroid cancer and from six studies of diabetes and thyroid cancer. The number of individuals from studies on physical activity was 939,305 (yielding 2,250 incident thyroid cancer cases) and from studies on diabetes it was 960,840 (yielding 1,230 cases). The summary relative risk (RR) estimate from cohort and case-control studies combined indicated no association between physical activity and thyroid cancer (summary RR 1.06, 95 % confidence interval (CI) 0.79-1.42). Subgroup-analyses revealed a significant positive association between physical activity and thyroid cancer in cohort studies (summary RR 1.28; 95 % CI 1.01-1.63), whereas the relation was suggestively inverse in case-control studies (summary RR 0.70; 95 % CI 0.48-1.03; p for heterogeneity = 0.005). Individuals with diabetes showed a borderline statistically significant increased risk of thyroid cancer compared with those without diabetes (summary RR 1.17; 95 % CI 0.99-1.39). The relations of physical activity and diabetes to thyroid cancer were not modified by sex, number of adjustment factors, and adjustments for adiposity, smoking, and study quality. In this comprehensive systematic review and meta-analysis, no significant association between physical activity and thyroid cancer was found. Diabetes showed a suggestive positive relation with risk of thyroid cancer.

Reproductive Risk Factors for Thyroid Cancer: A Prospective Cohort Study in Khon Kaen, Thailand

Because of the gender disparity in the incidence of thyroid cancer, this study aimed to determine the association between reproductive factors and thyroid cancer. A total of 10,767 eligible women from the Khon Kaen Cohort, recruited and interviewed between 1990 and 2001, were followed up until 2011. The data were linked to the Khon Kaen Population-Based Cancer Registry to detect thyroid cancer cases. There was 17 thyroid cancer cases detected, an incidence of 11.2 per 100,000 person-years, of which 70.6 % were papillary tumors. The incidence was apparently greater among those with an early age of menarche, nulligravida women, and oral contraceptive users. There was a trend for thyroid cancer to develop in relation to longer estrogen exposure. This evidence is inconclusive but warrants further investigation.

Nodule size is an independent predictor of malignancy in mutation-negative nodules with follicular lesion of undetermined significance cytology

In thyroid nodule fine-needle aspiration (FNA) cytology, the atypia of undetermined significance or follicular lesion of undetermined significance (AUS/FLUS) category has a 5-15% malignancy risk that increases to 85-99% when mutation testing for BRAF, RAS, RET/PTC, or PAX8/PPARγ is positive. However, negative testing does not exclude malignancy. The study objective was to identify clinical and imaging features that predict cancer in mutation-negative AUS/FLUS thyroid nodules. All patients were reviewed (April 2007 to April 2009) who had AUS/FLUS cytology, negative prospective molecular testing of FNA, and histopathology. Of the 230 nodules, 12 (5.2%) were malignant in 11 of 190 patients, and known clinical risk factors for thyroid cancer did not predict malignancy. On preoperative imaging, ≥1 suspicious ultrasound feature was identified in 33% of nodules and occurred regardless of histology (P = .23). Malignant mutation-negative AUS/FLUS nodules were larger than benign nodules (mean maximum diameter, 33.6 vs 24.0 mm; P = .007). On multivariate analysis, nodule size remained an independent predictor of malignancy (odds ratio, 1.043; P = .018). We observed no malignancies in 88 mutation-negative AUS/FLUS nodules <18.5 mm. Size is an independent predictor of malignancy in mutation-negative AUS/FLUS nodules and the risk increased 4.3% with every millimeter increase in nodule size. Selected patients with small, mutation-negative AUS/FLUS thyroid nodules may be managed with ultrasound surveillance in lieu of thyroidectomy.

Association between p53 Arg72Pro polymorphism and thyroid cancer risk: a meta-analysis

The p53 is a tumor suppressor gene which may be involved in the development of thyroid cancer. Studies investigating the association between p53 Arg72Pro polymorphism and thyroid cancer risk reported conflicting results. The aim of the meta-analysis was to derive a more precise assessment of the association between p53 Arg72Pro polymorphism and thyroid cancer risk. A literature search of PubMed and Web of Science from their inception through March 2013 was conducted. Odds ratios (OR) with 95% confidence intervals (95% CI) were used to assess the strength of the association. Eight case-control studies were included with a total of 874 thyroid cancer cases and 1,891 controls. The meta-analysis results showed that the p53 Arg72Pro polymorphism was only associated with thyroid cancer risk under the recessive model (ProPro vs. ArgArg/ArgPro: OR = 1.83, 95% CI 1.05-3.20, P = 0.034). However, there was no significant association between p53 Arg72Pro polymorphism and thyroid cancer risk under the other three genetic models (Pro vs. Arg: OR = 1.20, 95% CI 0.87-1.67, P = 0.262; ProPro vs. ArgArg: OR = 1.75, 95% CI 0.88-3.50, P = 0.113; ProPro/ArgPro vs. ArgArg: OR = 1.01, 95% CI 0.66-1.55, P = 0.968). Subgroup by ethnicity showed that there was no significant association between p53 Arg72Pro polymorphism and thyroid cancer risk in both Caucasians and Asians. Thus, p53 Arg72Pro polymorphism may be associated with thyroid cancer risk, and ProPro genotype is likely to be a risk factor of thyroid cancer.

Risk factors for well-differentiated thyroid cancer in men

Thyroid cancers are relatively rare tumors that appear more frequently in women than in men. Accordingly, most studies focus on studying risk factors for thyroid cancer in women and consequently on various hormonal or reproductive factors that are specific for women. The aim of our study was to examine risk factors for developing well-differentiated thyroid cancer in men. Heretofore, we did not encounter in the literature a study that was solely focused on studying risk factors for well-differentiated thyroid cancer in men. A case-control study was performed from 2005 to 2010. The case group included 204 consecutive well-differentiated thyroid cancers in male patients (180 papillary and 24 follicular including Hürthle cell). The control group comprised the same number of cases. Patients were individually matched by gender, age and place of residence. Statistical analysis included conditional univariate and multivariate logistic regression methods. According to univariate logistic regression, well-differentiated thyroid cancer in men was significantly related to smoking status, duration of smoking, number of cigarettes smoked per day, history of goiter or thyroid nodules, history of non-thyroid cancer, diabetes mellitus, radiotherapy of the head and neck, and history of malignant tumors. According to multivariate logistic regression, it was independently related to smoking status (OR = 0.36; 95% CI, 0.19-0.69), history of goiter or thyroid nodules (OR = 9.19; 95% CI, 1.25-64.58), and a history of malignant tumors (OR = 2.11; 95% CI, 1.19-7.33). Risk factors for well-differentiated thyroid cancer in men were goiter or thyroid nodules and family history of malignant tumors. Cigarette smoking was negatively associated with the disease.

Unbalanced estrogen metabolism in thyroid cancer

Well-differentiated thyroid cancer most frequently occurs in premenopausal women. Greater exposure to estrogens may be a risk factor for thyroid cancer. To investigate the role of estrogens in thyroid cancer, a spot urine sample was obtained from 40 women with thyroid cancer and 40 age-matched controls. Thirty-eight estrogen metabolites, conjugates and DNA adducts were analyzed by using ultraperformance liquid chromatography/tandem mass spectrometry and the ratio of adducts to metabolites and conjugates was calculated for each sample. The ratio of depurinating estrogen-DNA adducts to estrogen metabolites and conjugates significantly differed between cases and controls (p < 0.0001), demonstrating high specificity and sensitivity. These findings indicate that estrogen metabolism is unbalanced in thyroid cancer and suggest that formation of estrogen-DNA adducts might play a role in the initiation of thyroid cancer.

“Is there any association between insulin resistance and thyroid cancer? : a case control study”

Insulin stimulates proliferation of thyroid cells in culture. The presence of insulin resistance (IR) is associated with larger thyroid gland volume and an increased prevalence of thyroid nodules. The aim of this study was to investigate the presence of any possible association between IR and thyroid cancer. Forty-one patients with diffuse thyroid cancer (Group 1) were matched for age and gender with 41 patients with nodular goiter (Group 2). Both groups were compared in terms of frequency of IR, as estimated by the homeostasis model assessment, as well as other parameters of the metabolic syndrome (MetS). Fourteen patients (34.1 %) in each group had MetS. Twelve patients (29.3 %) in group 1 had IR compared to 10 (24.4 %) in group 2. Mean HOMA-IR scores in group 1 and 2 were 2.5 ± 2.2 and 1.8 ± 1.1, respectively. Thirty-two patients (78 %) in group 1 had a body mass index (BMI) of more than 25 compared to 33 patients (80.5 %) in group 2. The difference between groups with regard to HOMA-IR, the frequency of IR, BMI, and any of the parameters of MetS was statistically insignificant (p > 0.05). A subgroup analysis based on tumor size did not reveal a significant difference between patients with microcarcinoma (≤10 mm) and macrocarcinoma (>10 mm) in terms of any of the study parameters (p > 0.05). Neither MetS nor IR was a significant risk factor for thyroid cancer following logistic regression analysis (p > 0.05). IR is not more prevalent in patients with thyroid cancer. Some other pathologic mechanisms may be more prominent during thyroid carcinogenesis.

Obesity is a risk factor for thyroid cancer in a large, ultrasonographically screened population

Obesity is a well-known risk factor for many cancers, including those of the esophagus, colon, kidney, breast, and skin. However, there are few reports on the relationship between obesity and thyroid cancer. We conducted this study to determine whether obesity is a risk factor for thyroid cancer by systematically screening a selected population by ultrasonography. We obtained data from 15,068 subjects that underwent a routine health checkup from 2007 to 2008 at the Health Screening and Promotion Center of Asan Medical Center. Thyroid ultrasonography was included in the checkup, and suspicious nodules were examined by ultrasonography-guided aspiration. Those with a history of thyroid disease or family history of thyroid cancer were excluded from this study. In total, 15,068 subjects, 8491 men and 6577 women, were screened by thyroid ultrasonography. Fine-needle aspiration cytology was performed in 1427 of these patients based on the predefined criteria and thyroid cancer was diagnosed in 267 patients. The prevalence of thyroid cancer in women was associated with a high BMI (per 5 kg/m(2) increase) (odds ratios (OR)=1.63, 95% CI 1.24-2.10, P<0.001), after adjustment for age, smoking status, and TSH levels. There was no positive correlation between the prevalence of thyroid cancer in men and a high BMI (OR=1.16, 95% CI 0.85-1.57, P=0.336). There was no association between age, fasting serum insulin, or basal TSH levels and thyroid cancer in either gender. Obesity was associated with a higher prevalence of thyroid cancer in women when evaluated in a routine health checkup setting. This association between risk factor and disease was unrelated to serum insulin and TSH levels. Additional studies are needed to understand the mechanism(s) behind the association of obesity with thyroid cancer risk.

The clinical features of papillary thyroid cancer in Hashimoto’s thyroiditis patients from an area with a high prevalence of Hashimoto’s disease

BackgroundThe goal of this study was to identify the clinicopathological factors of co-existing papillary thyroid cancer (PTC) in patients with Hashimoto’s thyroiditis (HT) and provide information to aid in the diagnosis of such patients.MethodsThis study included 6109 patients treated in a university-based tertiary care cancer hospital over a 3-year period. All of the patients were categorised based on their final diagnosis. Several clinicopathological factors, such as age, gender, nodular size, invasive status, central compartment lymph node metastasis (CLNM) and serum thyroid-stimulating hormone (TSH) level, were compared between the various groups of patients.ResultsThere were 653 patients with a final diagnosis of HT. More PTC was found in those with HT (58.3%; 381 of 653) than those without HT (2416 of 5456; 44.3%; p < 0.05). The HT patients with co-occurring PTC were more likely to be younger, be female, have smaller nodules and have higher TSH levels than those without PTC. A multivariate analysis indicated that the presence of HT and higher TSH levels were risk factors for a diagnosis of PTC. In the PTC patients, the presence of HT or another benign nodule was a protective factor for CLNM, whereas no significant association was found for TSH levels.ConclusionPTC and HT have a close relationship in this region of highly prevalent HT disease. Based on the results of our study, we hypothesise that long-term HT leads to elevated serum TSH, which is the real risk factor for thyroid cancer.

Cancer differencié de la thyroïde de l’enfant

Thyroid carcinoma is a rare disease in children, and is mostly of the papillary histological type. Lymph node metastases are frequent at diagnosis, being present in 23 to 74% of the cases and can reveal the cancer in about one fourth of cases. Lung metastases are present at initial diagnosis in 6 to 20% of cases. The main known risk factor for thyroid cancer is a previous history of radiation exposure. Treatment includes surgery with total thyroidectomy and lymph node dissection and radioiodine therapy in case of extensive disease and distant metastases. Life-long thyroxine treatment is given to all patients. Long term prognosis is favourable, but thyroid cancer related deaths have been reported some decades after initial treatment.

Obesity and Excess Protein and Carbohydrate Consumption Are Risk Factors for Thyroid Cancer

Conflicting data concerning the association between obesity and differentiated thyroid cancer (DTC) may be attributed to the lack of records showing dietary intake and inadequate evaluation of nutrient composition. We evaluated 115 DTC patients carefully paired with 103 healthy control individuals by using a structured questionnaire, including a 24-h recordatory during 3 days, to investigate calorie intake and macronutrient (proteins, carbohydrates, and lipids) composition of the diet. We observed that excess weight (body mass index > 25 kg/m2) increased individual susceptibility to DTC [odds ratio (OR) = 3.787; 95% confidence interval (CI) = 1.115–6.814; P < 0.0001). This augmented risk was evident in women (OR = 1.925; 95% CI = 1.110–3.338; P = 0.0259) but not in men (P = 0.3498). Excess calorie intake was more frequent in patients with DTC than in controls (OR = 5.890; 95% CI = 3.124–11.103; P < 0.0001), and both excess protein (OR = 4.601; 95% CI = 1.634–12.954; P = 0.0039) and carbohydrate (OR = 4.905; 95% CI = 2.593–9.278; P < 0.0001) consumption were associated with an increased risk of DTC, contrarily to lipid/fiber intake and physical activity (P = 0.894 and 0.5932, respectively). In conclusion, our data indicate that overweight and risk of DTC are associated with higher protein and carbohydrate consumption than the rates recommended by the World Health Organization. The nutritional orientation should be part of preventive strategy targets designed to combat the increasing incidence of both obesity and DTC.

Polymorphisms in base excision repair genes and thyroid cancer risk

Thyroid cancer (TC) is the most frequent endocrine malignancy, accounting however for only 1-2% of all human cancers, and the best-established risk factor for TC is radiation exposure, particularly during childhood. Since the BER pathway seems to play an important role in the repair of DNA damage induced by IR and other genotoxicants, we carried out a hospital-based case-control study in order to evaluate the potential modifying role of 6 BER polymorphisms on the individual susceptibility to non-familial TC in 109 TC patients receiving iodine-131, and 217 controls matched for age (± 2 years), gender and ethnicity. Our results do not reveal a significant involvement of XRCC1 Arg194Trp and Arg399Gln, OGG1 Ser326Cys, APEX1 Asp148Glu, MUTYH Gln335His and PARP1 Val762Ala polymorphisms on the individual susceptibility towards TC, mostly in agreement with the limited available evidence. By histological stratification analysis, we observed that the association between the presence of heterozygosity in the MUTYH Gln335His polymorphism and TC risk almost reached significance for the papillary subtype of TC. This was the first time that the putative association between this polymorphism and TC susceptibility was evaluated. However, since the sample size was modest, the possibility of a type I error should not be excluded and this result should, therefore, be interpreted with caution. More in depth studies involving larger populations should be pursued in order to further clarify the potential usefulness of the MUTYH Gln335His genotype as a predictive biomarker of susceptibility to TC and the role of the remaining BER polymorphisms on TC susceptibility.

Retrospective measurements of airborne 129Iodine in Austria

The knowledge about the distribution of anthropogenic 129I is crucial for a successful establishment of transport mechanisms, fate and behaviour in the environment. In present study, the historical record of dry deposition of 129I in Austria over four decades back to the 1960s is reconstructed. The 129I/127I isotopic ratio of the order of 10−9–10−7 in airborne particles revealed a prominent anthropogenic 129I signature. The time profile of airborne 129I follows directly the pattern of the gaseous emissions from European reprocessing plants. Furthermore, temporal variations of 129I were traced monthly over two years. The potential risks of internal exposure to 129I are associated with both inhalation and ingestion. Since dose via inhalation was found insignificant, the thyroid equivalent dose from the internal exposure of 129I using a value of 10−8 for the isotopic ratio 129I/127I in the thyroid and ICRP reference man was calculated. The corresponding thyroid cancer risk factor of 10−11 for an adult from life-time exposure is one order of magnitude higher than for a 1-year old child. Due to low radiation toxicity of 129I the annual dose is 8 × 104 times lower than the dose limit of the National Research Council, USA which is 0.04 mSv y−1 to whole body or any organ for a combined beta and photon emitting radionuclide.

Association between Benign Thyroid and Endocrine Disorders and Subsequent Risk of Thyroid Cancer among 4.5 Million U.S. Male Veterans

Risk factors for thyroid cancer (TC) in males are poorly understood. OBJECTIVES, SETTING, AND PARTICIPANTS: Our aim was to evaluate the relationship between history of benign thyroid and endocrine disorders and risk of TC among 4.5 million male veterans admitted to U.S. Veterans Affairs hospitals between July 1, 1969, and September 30, 1996. We conducted a retrospective cohort study based on hospital discharge records with 1053 cases of TC. We estimated relative risks (RR) and computed 95% confidence intervals (CI) for TC using time-dependent Poisson regression models. To evaluate potential ascertainment bias and/or delayed diagnosis of TC, we also analyzed RR by time between diagnosis of benign disorder and TC (<5 or ≥ 5 yr). RR for TC were significantly elevated with many disorders and were often higher less than 5 yr compared with 5 yr or more before TC diagnosis. RR (95% CI) less than 5 yr/at least 5 yr were 67.9 (42.4-108.8)/28.9 (9.2-90.2) for thyroid adenoma, 77.8 (64.5-93.1)/25.9 (17.9-38.0) for nontoxic nodular goiter, 23.9 (13.8-41.3)/12.9 (4.8-34.4) for thyroiditis, 8.8 (6.9-11.3)/6.0 (3.8-9.6) for hypothyroidism, 6.4 (4.4-9.4)/ 2.0 (0.8-4.8) for thyrotoxicosis, and 1.2 (1.0-1.4)/1.1 (0.9-1.5) for diabetes. For some disorders, RR also significantly varied by attained age and race with younger patients and Blacks having higher RR than older patients and Whites. We found strong associations for a history of thyroid adenoma, nodular goiter, thyroiditis, or hypothyroidism with TC in males allowing for increased surveillance/delayed diagnosis and evidence that some of these associations are modified by age and race.

Seaweed consumption and the risk of thyroid cancer in women

Iodine is a suspected risk factor for thyroid cancer. Seaweed accounts for about 80% of Japanese people's iodine intake. We examined the association between seaweed consumption and the risk of thyroid cancer in Japanese women. Women participating in the Japan Public Health Center-based Prospective Study (n=52 679; age: 40-69 years) were followed up for a mean of 14.5 years; 134 new thyroid cancer cases, including 113 papillary carcinoma cases, were identified. Seaweed consumption was assessed using a food-frequency questionnaire and divided into three categories: 2 days/week or less (reference); 3-4 days/week; and almost daily. The Cox proportional hazards model was applied to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). Seaweed consumption was clearly associated with an increased risk of papillary carcinoma (HR for almost daily consumption compared with 2 days/week or less=1.71; 95% CI: 1.01-2.90; trend P=0.04). After stratification for menopausal status, an increased risk was observed in postmenopausal women (papillary carcinoma HR for almost daily consumption compared with 2 days/week or less=3.81, 95% CI: 1.67-8.68; trend P<0.01), but not in premenopausal women (HR=0.91, 95% CI: 0.44-1.91; trend P=0.76). This study identified a positive association between seaweed consumption and the risk of thyroid cancer (especially for papillary carcinoma) in postmenopausal women.

Anthropometric factors and physical activity and risk of thyroid cancer in postmenopausal women

To investigate the associations of anthropometric factors and physical activity with risk of thyroid cancer in a large prospective study. We examined these associations with risk of incident thyroid cancer in a cohort of 144,319 postmenopausal women enrolled in the Women's Health Initiative. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (95% CI) for factors of interest with risk of all thyroid cancer (n=294) and of the two major subtypes: papillary (n=245) and follicular thyroid cancer (n=32). After adjustment for covariates, measured height at baseline was positively associated with thyroid cancer overall (HR for highest vs. lowest quartile 1.48, 95% CI 1.04-2.13, p for trend 0.02) and with papillary carcinoma (HR 1.49, 95% CI 1.01-2.21, p for trend 0.03, respectively). For each 5cm-increase in height, the HR for all thyroid cancer was 1.15, 95% CI 1.04-1.27 and for papillary thyroid cancer was 1.14, 95% CI 1.03-1.27. In addition, self-reported weight at age 18 was positively associated with risk of papillary thyroid cancer. In contrast, baseline weight, body mass index, waist circumference, hip circumference, waist-hip ratio, weight change from age 18 to baseline, and level of self-reported recreational physical activity were not associated with risk. Our results suggest that attained stature is a risk factor for thyroid cancer in postmenopausal women. This association may reflect the influence of either genetic or environmental factors in early life on risk of thyroid cancer.

Prevalence of unsuspected thyroid nodules in adults on contrast enhanced 16- and 64-MDCT of the chest

To determine the prevalence of unsuspected thyroid nodules on contrast enhanced 16- and 64-modified discrete cosine transform (MDCT) of the chest, in a population of adult outpatients imaged for indications other than thyroid disease. This retrospective study involved review of intravascular contrast-enhanced MDCT scans of the chest from 3077 consecutive adult outpatients, to identify unsuspected thyroid nodules. Exclusion criteria included history of thyroid cancer, known thyroid nodules or thyroid disease and risk factors for thyroid cancer, as evidenced by their medical records. One of 9 radiologists recorded number of nodules, location and bidirectional measurement of largest nodule, as well as amount of thyroid visualized on the chest computed tomography (CT). Presence of nodule was correlated with age, gender, race and percentage of thyroid imaged. A total of 2510 (2510/3077 or 81.6%) study subjects were included in the data analysis; among them, one or more nodules were identified in 629 subjects (629/2510 or 25.1%), with 242 (242/629 or 38.5%) having multiple nodules. Patients with nodule(s) were significantly older than those without (64 ± 13 years vs 58 ± 14 years, P < 0.0001), and female gender was associated with presence of nodule(s) (373/1222 or 30.5% vs 256/1288 or 19.9%, P < 0.0001). Women were also more likely having multiple nodules (167/373 or 44.8%) compared to men (75/256 or 29.3%, P < 0.0001). The majority of nodules (427/629 or 67.9%) were less than 1 cm. This retrospective review revealed a prevalence of 25.1% for unsuspected thyroid nodules on contrast-enhanced chest CT.