Japan Public Health Research Articles

Dietary Acrylamide Intake and the Risks of Renal Cell, Prostate, and Bladder Cancers: A Japan Public Health Center-Based Prospective Study.

Acrylamide can be carcinogenic to humans. However, the association between the acrylamide and the risks of renal cell, prostate, and bladder cancers in Asians has not been assessed. We aimed to investigate this association in the Japan Public Health Center-based Prospective Study data in 88,818 Japanese people (41,534 men and 47,284 women) who completed a food frequency questionnaire in the five-year follow-up survey in 1995 and 1998. A validated food frequency questionnaire was used to assess the dietary acrylamide intake. Cox proportional hazard regression models were used to estimate hazard ratios and 95% confidence intervals (CIs). During a mean follow-up of 15.5 years (15.2 years of prostate cancer), 208 renal cell cancers, 1195 prostate cancers, and 392 bladder cancers were diagnosed. Compared to the lowest quintile of acrylamide intake, the multivariate hazard ratios for the highest quintile were 0.71 (95% CI: 0.38–1.34, p for trend = 0.294), 0.96 (95% CI: 0.75–1.22, p for trend = 0.726), and 0.87 (95% CI: 0.59–1.29, p for trend = 0.491) for renal cell, prostate, and bladder cancers, respectively, in the multivariate-adjusted model. No significant associations were observed in the stratified analyses based on smoking. Dietary acrylamide intake was not associated with the risk of renal cell, prostate, and bladder cancers.

Weight change during middle age and risk of stroke and coronary heart disease: The Japan Public Health Center–based Prospective Study

Background and aimsThe impact of weight changes in middle age on the incidence of cardiovascular disease has not been well elucidated. We investigated whether a 5-year weight change was associated with risk of stroke and coronary heart disease (CHD) in middle-aged individuals. MethodsWe analyzed data of 74,928 participants aged 40–69 years who provided responses to the baseline and 5-year follow-up questionnaires in the Japan Public Health Center–based Prospective Study. Weight change was calculated by subtracting self-reported weight at baseline from that at 5-year follow-up. Stroke and CHD events were confirmed by reviewing hospital records. ResultsDuring 997,406 person-years of follow-up, we documented 3,975 stroke and 914 CHD events. The multivariable HRs of stroke for losing ≥5 kg compared to stable weight (change ≤2 kg) was 1.17 (95% CI, 1.01–1.37) in men versus 1.33 (1.13–1.57) for losing ≥5 kg and 1.61 (1.36–1.92) for gaining ≥5 kg in women (U-shaped association). These associations did not change after the exclusion of early events. The multivariable HR of CHD for gaining ≥5 kg was 1.22 (0.95–1.58) in men. After exclusion of early events within another 5 years, that positive association became stronger [multivariable HR 1.34 (1.00–1.82)]. ConclusionsWeight gain during middle age was associated with an increased risk of stroke in women and an increased risk of CHD in men. Weight loss was associated with an increased risk of stroke in both men and women.

Plasma phospholipid n-3 polyunsaturated fatty acids and major depressive disorder in Japanese elderly: the Japan Public Health Center-based Prospective Study

The beneficial effects of n-3 polyunsaturated fatty acids (PUFAs) such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on depression are not definitively known. In a previous population-based prospective cohort study, we found a reverse J-shaped association of intake of fish and docosapentaenoic acid (DPA), the intermediate metabolite of EPA and DHA, with major depressive disorder (MDD). To examine the association further in a cross-sectional manner, in the present study we analyzed the level of plasma phospholipid n-3 PUFAs and the risk of MDD in 1,213 participants aged 64–86 years (mean 72.9 years) who completed questionnaires and underwent medical check-ups, a mental health examination, and blood collection. In multivariate logistic regression analysis, odds ratios and 95% confidence intervals were calculated for MDD according to plasma phospholipid n-3 PUFA quartiles. MDD was diagnosed in 103 individuals. There were no significant differences in any n-3 PUFAs (i.e., EPA, DHA, or DPA) between individuals with and without MDD. Multivariate logistic regression analysis showed no significant association between any individual n-3 PUFAs and MDD risk. Overall, based on the results of this cross-sectional study, there appears to be no association of plasma phospholipid n-3 PUFAs with MDD risk in the elderly Japanese population.

Dietary Acrylamide Intake and the Risk of Hematological Malignancies: The Japan Public Health Center-Based Prospective Study.

Acrylamide, which is present in many daily foods, is a probable human carcinogen. In 2002, it was identified in several common foods. Subsequently, western epidemiologists began to explore the relationship between dietary acrylamide exposure and cancer risk; however, limited suggestive associations were found. This prospective study aimed to examine the association between dietary acrylamide intake and the risk of hematological malignancies, including malignant lymphoma (ML), multiple myeloma (MM), and leukemia. We enrolled 85,303 participants in the Japan Public Health Center-based Prospective study on diet and cancer as from 1995. A food frequency questionnaire that included data on acrylamide in all Japanese foods was used to assess dietary acrylamide intake. We applied multivariable adjusted Cox proportional hazards models to reckon hazard ratios (HRs) for acrylamide intake for both categorical variables (tertiles) and continuous variables. After 16.0 median years of follow-up, 326 confirmed cases of ML, 126 cases of MM, and 224 cases of leukemia were available for final multivariable-adjusted analysis. HRs were 0.87 (95% confidence interval [CI]: 0.64–1.18) for ML, 0.64 (95% CI: 0.38–1.05) for MM, and 1.01 (95% CI: 0.71–1.45) for leukemia. Our results implied that acrylamide may not be related to the risk of hematological malignancies.

Sugary Drink Consumption and Subsequent Colorectal Cancer Risk: The Japan Public Health Center-Based Prospective Cohort Study.

Most studies examining the associations of sugary drink consumption on colorectal cancer risk have been conducted in Western populations. This study consisted of 74,070 participants in the Japan Public Health Center-based Prospective Study who completed a food frequency questionnaire (1995-1999). The participants were followed until December 2013 to investigate the associations between sugary drink consumption and colorectal cancer risk using Cox proportional hazards regression models. Among the 74,070 participants, mean age was 56.5 years at baseline, with a mean body mass index (BMI) of 23.5 and a mean daily consumption of 286 mL/day for men and 145 mL/day for women. During a follow-up of 15 years, 1,648 colorectal cancer cases were identified. No overall greater risk of colorectal cancer was observed among men [multivariable HR = 0.84; 95% confidence of interval (CI), 0.70-1.02; ≥254 mL/day vs. nonconsumers] and women (HR = 1.20; 95% CI, 0.96-1.50, ≥134 mL/day vs. nonconsumers). Sugary drink consumption was associated with colon cancer among women (HR = 1.36; 95% CI, 1.03-1.78, ≥134 mL/day vs. nonconsumers). HRs for proximal colon cancer among women who consumed sugary drinks, as compared with nonconsumers, were 1.47 (95% CI, 1.03-2.10) for sugary drink consumption less than 134 mL/day, and 1.45 (95% CI, 1.01-2.09) for at least 134 mL/day. In this large prospective cohort of Japanese with a moderate sugary drink consumption level and low prevalence of obesity, we observed a 36% increased risk of colon cancer in women. Our findings highlight the importance of subsite- and sex-specific investigation.

The Association Between Habitual Sleep Duration and Mortality According to Sex and Age: The Japan Public Health Center-based Prospective Study.

BackgroundShort and long sleep durations are associated with mortality outcomes. The association between sleep duration and mortality outcomes may differ according to sex and age.MethodsParticipants of the Japan Public Health Center-based prospective study (JPHC Study) were aged 40–69 years and had completed a detailed questionnaire on lifestyle factors. Sex- and age-stratified analyses on the association between habitual sleep duration and mortality from all-causes, cardiovascular diseases (CVD), cancer and other causes included 46,152 men and 53,708 women without a history of CVD or cancer. Cox proportional hazards regression models, adjusted for potential confounders, were used to determine hazard ratios and 95% confidence intervals.ResultsMean follow-up time was 19.9 years for men and 21.0 years for women. In the multivariable sex-stratified models, some categories of sleep durations ≥8 hours were positively associated with mortality from all-causes, CVD, and other causes in men and women compared with 7 hours. The sex- and age-stratified analyses did not reveal any major differences in the association between sleep duration and mortality outcomes in groups younger and older than 50 years of age. The only exception was the significant interaction between sleep duration and age in women for mortality from other causes.ConclusionsSleep durations ≥8 hours are associated with mortality outcomes in men and women. Age may be an effect modifier for the association between sleep duration and mortality from other causes in women.

Intake of Vegetables and Fruits and the Risk of Cataract Incidence in a Japanese Population: The Japan Public Health Center-Based Prospective Study.

BackgroundAlthough the consumption of vegetables and fruits is reported to influence the risk of cataract, no prospective study of this association from Asia has yet appeared. Here, we investigated the association between vegetable and fruit intake and cataract incidence in a large-scale population-based prospective cohort study in Japan.MethodsThis study included 32,387 men and 39,333 women aged 45–74 years who had no past history of cataract and had completed a dietary questionnaire of the Japan Public Health Center-based Prospective Cohort Study. The incidence of cataract was evaluated after 5-year follow-up. We used multiple logistic regression analyses to estimate the sex-specific odds ratios (ORs), with adjustment for confounding factors.ResultsWe identified 1,836 incident cataracts in 594 men and 1,242 women. In men, the OR for cataract was decreased with higher intake of vegetables (ORQ5 vs Q1, 0.77; 95% confidence interval [CI], 0.59–1.01; Ptrend across quartile categories = 0.03) and cruciferous vegetables (ORQ5 vs Q1, 0.74; 95% CI, 0.57–0.96; Ptrend = 0.02). In contrast, the OR for cataract was increased with higher intake of vegetables among women (ORQ5 vs Q1, 1.28; 95% CI, 1.06–1.53; Ptrend = 0.01). Green and yellow vegetable and fruit intake were not associated with cataract in either sex.ConclusionsThis study suggests that vegetables may reduce the risk of cataract in men, but not in women.

Validity of a food frequency questionnaire for the estimation of total polyphenol intake estimates and its major food sources in the Japanese population: the JPHC FFQ Validation Study.

We examine the validity and reproducibility of a food frequency questionnaire (FFQ) in a subsample of participants in the Japan Public Health Center-based Prospective Cohort Study using a database of polyphenol-containing foods commonly consumed in the Japanese population. Participants of the validation study were recruited from two different cohorts. In Cohort I, 215 participants completed a 28-d dietary record (DR) and the FFQ, and in Cohort II, 350 participants completed DRs and the FFQ. The total polyphenol intake estimated from the 28-d DR and FFQ were log-transformed and adjusted for energy intake by the residual method. Spearman correlation coefficients (CCs) between estimates from the FFQ and 28-d DR as well as two FFQs administered at a 1-year interval were computed. Median intakes of dietary polyphenols calculated from the DRs were 1172 mg/d for men and 1024 mg/d for women in Cohort I, and 1061 mg/d for men and 942 mg/d for women in Cohort II. The de-attenuated CCs for polyphenol intake between the DR and FFQ were 0⋅47 for men and 0⋅37 for women in Cohort I and 0⋅44 for men and 0⋅50 for women in Cohort II. Non-alcoholic beverages were the main contributor to total polyphenol intake in both men and women, accounting for 50% of total polyphenol intake regardless of cohort and gender, followed by alcoholic beverages and seasoning and spices in men, and seasoning and spices, fruits and other vegetables in women. The present study showed that this FFQ had moderate validity and reproducibility and is suitable for use in future epidemiological studies.

Dietary fiber intake and risk of gastric cancer: The Japan Public Health Center-based prospective study.

Evidence of the association between dietary fiber intake and gastric cancer (GC) risk from prospective studies is limited. We examined the association between dietary fiber intake and GC risk in a large prospective study. A total of 91 946 eligible Japanese aged 45 to 74 years (42 773 men and 49 173 women) participated in a population-based cohort study (Japan Public Health Center-based prospective study). From a validated food frequency questionnaire with 138 food items, total and food source-specific dietary fiber intake was calculated as exposure. The hazard ratio (HR) and the 95% confidence interval (CI) of GC incidence according to quintile of dietary fiber intake were examined after adjusting for confounding factors. In total, 2228 GC cases (1559 men and 669 women) were observed during the 15.0 years follow-up. Total dietary fiber intake was not associated with GC risk; however, a marginally increased risk trend because of high HR in the highest quintile of total fiber intake was found in women (HR [95% CI] in Q5 vs Q1: 0.95 [0.79-1.14], P for trend .30 in men, HR [95% CI] 1.25 [0.98-1.61], P for trend .05 in women). Stratification by tumor location did not change the results. A marginal but not significant inverse trend was observed regarding cereal fiber intake and GC risk in men. Total dietary fiber intake was not associated with GC risk. Further studies are warranted to confirm this association.

日本の運動疫学コホート（6） 多目的コホート研究 The Japan Public Health Center-based prospective Study (JPHC Study)

日本の運動疫学コホート（6） 多目的コホート研究 The Japan Public Health Center-based prospective Study (JPHC Study)

Fermented and nonfermented soy foods and the risk of breast cancer in a Japanese population-based cohort study.

BackgroundAlthough preclinical studies suggest that fermented soy foods may have a protective effect against breast cancer, no prospective cohort studies have examined this association.ObjectiveOur study examined the association between fermented and nonfermented soy food intake and breast cancer risk using a population‐based prospective cohort study in Japan.MethodsWe included a total of 47,614 women aged 45–74 years in an analysis of the Japan Public Health Center‐based Prospective Study (JPHC Study). A validated food frequency questionnaire (FFQ) was used for the assessment of dietary intake. Breast cancer incidence was analyzed by multivariate Cox proportional hazards regression models.ResultsDuring an average of 15.5 years of follow‐up, 825 breast cancer cases were newly identified. We found no association of intake of soy foods with breast cancer risk, regardless of fermentation, with multivariate hazard ratios (HRs) and 95% confidence intervals (CIs) for the highest quartiles of fermented and nonfermented soy food intake of 0.94 (0.67, 1.32) and 1.15 (0.85, 1.57) compared with the lowest quartile (p for trend = 0.305 and 0.393). Unlike nonfermented soy, higher intake of fermented soy foods was associated with a significant decrease in the risk of nonlocalized breast cancer. The HR and 95% CI in the highest compared to lowest intake category of fermented soy foods was 0.53 (0.28, 0.99) versus nonfermented soy foods 0.85 (0.51, 1.42) (p for trend = 0.026 and 0.797).ConclusionsOur analyses showed that fermented soy foods had no association with overall breast cancer but may be associated with decreased risk of nonlocalized breast cancer.

Dietary Acrylamide Intake and the Risk of Pancreatic Cancer: The Japan Public Health Center-Based Prospective Study.

Acrylamide is a probable carcinogen in humans. Few studies have assessed dietary acrylamide intake and the risk of pancreatic cancer; however, these studies are based on Western populations. Our purpose was to investigate the association of dietary acrylamide intake with the risk of pancreatic cancer utilizing data from the Japan Public Health Center-based Prospective Study. We evaluated the data of 89,729 participants aged 45–74 years, who replied to a questionnaire on past medical history and lifestyle habits from 1995–1998. Dietary acrylamide intake was estimated utilizing a validated food frequency questionnaire. We calculated the hazard ratios and 95% confidence intervals by using Cox proportional-hazards regression models. The average follow-up was 15.2 years, and 576 cases of pancreatic cancer were diagnosed. In the multivariate-adjusted model, an association between dietary acrylamide intake and pancreatic cancer risk was not demonstrated (hazard ratio for the highest vs. lowest quartile = 0.83, 95% confidence interval: 0.65–1.05, p for trend = 0.07). Furthermore, in the analyses stratified by sex, smoking status, coffee consumption, green tea consumption, alcohol consumption, and body mass index, no significant association was detected. Dietary acrylamide intake was not associated with the pancreatic cancer risk in Japanese individuals.

Soy and isoflavone consumption and subsequent risk of prostate cancer mortality: the Japan Public Health Center-based Prospective Study.

Although many epidemiological studies have reported the preventive effects of soy products and isoflavones on prostate cancer, our previous studies reported that the association between soy and isoflavones and prostate cancer incidence differed according to stage. It is more important to identify modifiable risk factors related to lethal prostate cancer. Here, we investigated the association between soy, soy products and isoflavones intake and prostate cancer mortality, in a prospective study in Japan. We conducted a population-based prospective study in 43580 Japanese men with no history of cancer or cardiovascular disease (aged 45-74 years). Participants completed a validated questionnaire which included 138 food items. We followed participants from 1995 to 2016. Hazard ratios (HRs) and 95% confidence intervals (CIs) of prostate cancer mortality were calculated according to quintiles of soy products and isoflavones intake, using Cox hazard proportional hazards regression. During 16.9 years follow-up, we registered 221 deaths from prostate cancer. Isoflavones and soy products intake was associated with an increased risk of prostate cancer death, with multivariate HRQ5 vs. Q1=1.39, 95% CI = 0.87-2.20, p for trend = 0.04 for isoflavones and multivariate HRQ5 vs. Q1=1.76, 95% CI = 1.10-2.82, p for trend = 0.04 for soy food. Our study suggested that high intake of soy and isoflavones might increase the risk of prostate cancer mortality.

Cross-Sectional Association Between Employment Status and Self-Rated Health Among Middle-Aged Japanese Women: The Influence of Socioeconomic Conditions and Work-Life Conflict.

BackgroundFew studies examining the impact for women of employment status on health have considered domestic duties and responsibilities as well as household socioeconomic conditions. Moreover, to our knowledge, no studies have explored the influence of work-family conflict on the association between employment status and health. This research aimed to investigate the cross-sectional associations between employment status (regular employee, non-regular employee, or self-employed) with self-rated health among Japanese middle-aged working women.MethodsSelf-report data were obtained from 21,450 working women aged 40–59 years enrolled in the Japan Public Health Center-based Prospective Study for the Next Generation (JPHC-NEXT Study) in 2011–2016. Multivariate odds ratios (ORs) and 95% confidence intervals (CIs) were calculated for poor self-rated health (‘poor’ or ‘not very good’) by employment status. Sub-group analyses by household income and marital status, as well as mediation analysis for work-family conflict, were also conducted.ResultsAdjusted ORs for the poor self-rated health of non-regular employees and self-employed workers were 0.90 (95% CI, 0.83–0.98) and 0.84 (95% CI, 0.75–0.94), respectively, compared with regular employees. The identified association of non-regular employment was explained by work-family conflict. Subgroup analysis indicated no statistically significant modifying effects by household income and marital status.ConclusionAmong middle-aged working Japanese women, employment status was associated with self-rated health; non-regular employees and self-employed workers were less likely to report poor self-rated health, compared with regular employees. Lowered OR of poor self-rated health among non-regular employees may be explained by their reduced work-family conflict.

Association of Choroidal Thickness with Intermediate Age-Related Macular Degeneration in a Japanese Population

To determine the relationship of choroidal thickness with the early stages of age-related macular degeneration (AMD) and their disease features in a Japanese population. Cross-sectional survey. A total of 1293 Japanese persons 65 to 86 years of age residing in the Saku area who underwent eye screening as part of the Japan Public Health Center-based Prospective Study. Comprehensive ophthalmic assessment included fundus photography, measurement of intraocular pressure, and determination of refractive status. OCT with enhanced depth imaging mode was performed and subfoveal choroidal thickness was assessed. Multinomial logistic regression models were used to assess the relationships of choroidal thickness with the early stages of AMD, namely early AMD and intermediate AMD, and their disease features, after adjustment for potential confounders. Relationship of choroidal thickness with early AMD, intermediate AMD, and their disease features. Of 1293 potential participants, 901 (mean age, 73.2 years) had choroidal thickness data, fundus photographs of sufficient quality, and no concomitant retinal disease (including 5 with late AMD). Mean choroidal thickness was 246.1 μm, 15.1% had early AMD, and 9.0% had intermediate AMD. After adjustment for age, gender, and refractive status, choroidal thickness was associated positively with presence of intermediate AMD (for each 1- standard deviation [SD] μm increase: odds ratio [OR], 1.43; 95% confidence interval [CI], 1.13-1.81), whereas no significant association was found with presence of early AMD. Among intermediate AMD features, choroidal thickness was associated positively with presence of AMD pigmentary abnormalities (associated with at least medium drusen; for each 1-SD μm increase: OR, 2.21; 95% CI, 1.42-3.42), whereas no significant association was found with presence of large drusen alone. In addition, among large drusen subtypes, choroidal thickness was associated positively with presence of pachydrusen (for each 1-SD μm increase: OR, 1.53; 95% CI, 1.10-2.13). Furthermore, exploratory analysis revealed that choroidal thickness was associated positively with presence of non-AMD pigmentary abnormalities (for each 1-SD μm increase: OR, 1.92; 95% CI, 1.31-2.18). Choroidal thickness seems to be associated with the pathology of intermediate AMD and its features in Asians.

Fermented soy products intake and risk of cardiovascular disease and total cancer incidence: The Japan Public Health Center-based Prospective study.

The association of fermented soy products, separately from total soy products, with cardiovascular disease (CVD) and total cancer has not been reported. We examined this association in a population-based prospective cohort study in Japan. We studied 79,648 participants (42,788 women; 36,860 men) aged 45-74 years without a history of cancer, myocardial infarction, or stroke. Participants completed a food frequency questionnaire (1995-1998) and were followed to 2009-2012. Cox proportional hazards regression analysis was used to calculate the hazard ratios (HR) and 95% confidence intervals (CI) of incidence of CVD and total cancer according to quartiles of total soy products, nonfermented soy products, fermented soy products, miso soup, natto, total isoflavones from soy products, isoflavones from nonfermented soy products, and isoflavones from fermented soy products. In women, we observed a significant inverse association between fermented soy product intake and the risk of CVD (multivariate HR in the highest compared with the lowest quartile of fermented soy product intake: 0.80; 95% CI: 0.68, 0.95; P for trend = 0.010), and also found significant inverse associations for natto and isoflavones among fermented soy products. In site-specific analysis, we observed a similar, significant inverse association between fermented soy product intake and the risk of stroke in women. We found no significant association between any soy product and risk of CVD in men or total cancer in both sexes. Intake of fermented soy products such as natto was inversely associated with the risk of CVD in women.

Soy Intake and Colorectal Cancer Risk: Results from a Pooled Analysis of Prospective Cohort Studies Conducted in China and Japan

Soy is commonly consumed in east Asian countries and is suggested to reduce colorectal cancer (CRC) risk. However, results from epidemiologic studies are inconsistent, despite the anti-inflammatory and antiproliferative properties of soy isoflavones and soy protein. We evaluated the association between soy isoflavones and soy protein and CRC risk using 4 prospective cohort studies from China and Japan. Data were pooled from the Shanghai Women's Health Study (SWHS), Shanghai Men's Health Study (SMHS), Japan Public Health Center-based Prospective Study Cohort 1 (JPHC1), and Cohort 2 (JPHC2). Cox proportional hazards models estimated HRs and corresponding 95% CIs for the association of soy protein and isoflavone intake with CRC risk. The study included 205,060 individuals, among whom 2971 were diagnosed with incident CRC over an average follow-up of 12.7 y. No statistically significant associations with CRC risk were observed for soy protein or isoflavone intake. No association was observed among ever smokers consuming higher isoflavones (HRisoflavones: 0.83; 95% CI: 0.68, 1.00) and soy protein (HRsoy protein: 0.81; 95% CI: 0.39, 1.10). However, risk reductions were observed among premenopausal women with a body mass index [BMI (kg/m2)] <23.0 at baseline for higher isoflavone (HRisoflavones: 0.58, 95% CI: 0.34, 0.98). No evidence for an overall reduction in CRC risk by increasing soy food intake (i.e., protein or isoflavones) was observed. However, the association between soy and CRC risk may vary by BMI, smoking, and menopausal status among women. Future investigations are needed to further understand the biologic mechanisms observed.

Dietary Acrylamide Intake and the Risk of Liver Cancer: The Japan Public Health Center-Based Prospective Study.

Acrylamide has been studied for its carcinogenicity in experimental animals, causing tumors at several organ sites, and has been considered probably carcinogenic to humans as well. Given the small number of epidemiological studies that have been conducted, it is still uncertain whether the consumption of acrylamide is associated with liver cancer. Therefore, we investigated a study to determine the possible relationship between acrylamide intake and the risk of developing liver cancer in the Japanese population. A total of 85,305 participants, from the Japan Public Health Center-based Prospective Study, who provided a validated food-frequency questionnaire were enrolled between 1995 and 1998. During a median of 16.0 years follow-up, 744 new liver cancer cases were identified. Compared to the lowest tertile of acrylamide consumption (<4.8 µg/day), the multivariate hazard ratio (HR) for the highest tertile (≥7.6 µg/day) was 0.79 (95% confidence interval [CI] = 0.65–0.95) for liver cancer using multivariable model 1, adjusted for smoking status, body mass index (BMI), physical activity, medical history, and alcohol consumption; whereas the inverse relationship disappeared after additionally adjusting for coffee consumption in multivariable model 2 with HR of 1.08 (95% CI = 0.87–1.34) for the highest tertile. The effect of dietary acrylamide intake on the risk of liver cancer was not observed in the Japanese population.

Body mass index and height in relation to brain tumor risk in a Japanese population

PurposeAlthough height and body mass index (BMI) are reported to be positively associated with several common cancers, evidence regarding their association with brain tumor risk remains sparse, particularly in Asian populations. In this study, we analyzed the association between height and BMI and brain tumor risk in a Japanese population using a large population-based prospective cohort study. MethodsA total of 102,925 participants (48,213 men and 54,712 women) enrolled in the Japan Public Health Center–based Prospective Study were followed from baseline, namely 1990 for cohort I and 1993 for cohort II, until 2012. Information on participants’ dietary and lifestyle habits, including height and body weight, was collected through survey questionnaires administered at baseline. We used the Cox proportional hazards regression model to estimate hazard ratios and 95% confidence intervals (CIs) for brain tumor incidence, with adjustment for potential confounding variables. ResultsDuring an average follow-up of 18.1 years, 157 (70 men and 87 women) cases of brain tumor were newly diagnosed. BMI showed a statistically insignificant positive association with the risk of brain tumor. In addition, statistically significant positive trends were seen for men and meningioma, with multivariable-adjusted hazard ratios for a BMI of 27.5 to less than 40 versus 18.5 to less than 23 kg per m2 of 2.14 (95% CI = 0.99–4.59) (P = 0.03) and 1.98 (95% CI = 0.84–4.67) (P = 0.046), respectively. In contrast, height showed no clear association with brain tumor risk, overall or in subgroup analysis. ConclusionsCompared with a BMI of 18 to less than 23.5 kg per m2, a higher BMI was associated with higher risk of brain tumor, particularly in men and with meningioma.

Intensity-specific validity and reliability of the Japan Public Health Center-based prospective study-physical activity questionnaire.

The Japan Public Health Center-based prospective study- physical activity questionnaire (JPHC-PAQ) was originally developed and validated for total physical activity (total PA). However, it is uncertain whether JPHC-PAQ could also estimate intensity-specific physical activity. The present study aims to evaluate the validity and reliability of intensity-specific physical activity by the JPHC-PAQ against 24-hour activity records (24h-R). One-hundred and ten participants were chosen from those who had enrolled in the JPHC cohort. Time spent for total PA and intensity-specific physical activity, i.e. moderate (MPA), vigorous (VPA) and moderate-to-vigorous physical activity (MVPA) was estimated by JPHC-PAQ. In addition, the volume of PA was calculated by time of each activity multiplied by intensity of activity. For validity assessment, estimated physical activities were compared with 24h-R. For reliability evaluation, a retest was conducted 3-6months after the first survey was answered. Moderately strong correlation between JPHC-PAQ and 24h-R was observed for total PA estimations (Spearman's rho=0.672). In addition, moderate correlations were found for MPA (activity time: rho=0.345, activity volume: rho=0.300) and MVPA (activity time: rho=0.563, activity volume: rho=0.672). Whereas, little association was found for VPA time and volume. As for reliability, moderately strong correlation was found for both total and intensity-specific physical activity in the test-retest (rho=0.482-0.745). In addition to total PA, the JPHC-PAQ showed acceptable validity and reliability for intensity-specific physical activity, especially in estimating MVPA and MPA.