Physical activity and risk of colorectal cancer in Japanese men and women: the Japan Public Health Center-based prospective Study

Objective To prospectively examine the association between physical activity and the risk of developing colorectal cancer in a large population-based cohort study of Japanese men and women, and to investigate whether the effects of physical activity on colorectal cancer risk differ by sex and subsite. Methods We analyzed data from a population-based cohort of 65,022 subjects. A total of 486 incident colorectal cancers (154 proximal colon, 166 distal colon and 149 rectal cancers) was identified during 6 years of follow-up. Results We observed a significant inverse association between physical activity and the risk of developing colorectal cancer, particularly colon cancer, among men. Relative to men in the lowest level of metabolic equivalent (MET) hours per day, those in the highest level had a RR of 0.69 (95% CI = 0.49–0.97). A significant decrease in risk of colorectal cancer was associated with increasing MET hours per day among men. This inverse association was essentially limited to colon cancer. A significant decrease in risk with increasing MET-hour score was observed predominantly for proximal colon cancer among men. In contrast, no significant decrease was seen among women. Conclusion These findings suggest that physical activity may prevent colon cancer among Japanese men. Study group members are listed in the Appendix at the end of this article.     

Dietary fiber intake and subsequent risk of colorectal cancer: the Japan Public Health Center-based prospective study

Results on the association of dietary fiber intake with colorectal cancer risk were inconsistent among previous large prospective studies, but studies in non-Western populations are lacking. Consequently, the authors investigated the association between dietary fiber intake and the subsequent risk of colorectal cancer in a prospective cohort study of a Japanese population. Dietary fiber intake was estimated from food-frequency questionnaires comprising 44 or 52 items at the baseline survey and 138 food items at a 5-year follow-up survey. The authors identified 907 cases of colorectal adenocarcinoma diagnosed pathologically in 86,412 subjects during a 10-year follow-up from the baseline survey. After the 5-year follow-up survey, 522 cases were identified in 78,326 subjects during a 5.8-year follow-up. The authors estimated the multivariate-adjusted hazard ratios of colorectal cancer for dietary fiber intake using Cox's proportional hazards model. The authors found no statistically significant association between dietary fiber intake and colorectal cancer in analyses using data either from the baseline survey or from the 5-year follow-up survey. However, the risk of only the lowest quintile was high, compared with the second to the fifth quintiles. Furthermore, the lowest subtertile in the lowest quintile was associated with an increased risk in women (hazard ratio(Sub1 vs. Q5), 2.3; 95% confidence interval, 1.0-5.2). In conclusion, although a minor effect cannot be ruled out, the results did not support a hypothesis of a dose-dependent protective effect of dietary fiber intake against colorectal cancer.     

Alcohol and smoking and subsequent risk of prostate cancer in Japanese men: The Japan Public Health Center‐based prospective study

Although alcohol and smoking have not been established as risk factors for prostate cancer, they are important risk factors for other human cancers and potentially major avoidable factors. Alcohol drinkers and smokers might be less likely to get screening, which might lead to attenuation of the positive association. Here, we investigated the association of alcohol drinking and smoking and prostate cancer according to stage, as well as prostate cancer detected by subjective symptoms, in a large prospective study among Japanese men. The Japan Public Health Center‐based prospective study (JPHC study) was established in 1990 for Cohort I and in 1993 for Cohort II. Subjects were 48,218 men aged 40–69 years who completed a questionnaire, which included their alcohol and smoking habits at baseline, and who were followed until the end of 2010. During 16 years of follow‐up, 913 men were newly diagnosed with prostate cancer; of whom 248 had advanced cases, 635 were organ‐localized and 30 were of an undetermined stage. Alcohol consumption was dose‐dependently associated with advanced prostate cancer [nondrinkers: reference, 0–150 g/week: hazard ratio (HR) = 1.23, 95% confidence interval (CI) = 0.83–1.82; 150–300 g/week: HR = 1.51, 95% CI = 1.04–2.19; ≥300 g/week: HR = 1.41, 95% CI = 0.97–2.05, p for trend = 0.02]. The positive association was not substantially changed among cancers detected by subjective symptoms. Smoking was inversely associated with prostate cancer among total subjects, but tended to increase the risk of advanced prostate cancer detected by subjective symptoms. In conclusion, abstinence from alcohol and prohibition of smoking might be important factors in the prevention of advanced prostate cancer.     

Plasma C-reactive protein and risk of colorectal cancer in a nested case-control study: Japan Public Health Center-based prospective study.

C-reactive protein is a biomarker indicating inflammation in the body. We measured plasma C-reactive protein to assess whether this biomarker could predict subsequent colorectal cancer incidence. A nested case-control study was conducted within a Japan Public Health Center-based prospective study. During a 11.5-year follow-up, 375 newly diagnosed colorectal cancers were identified in a cohort of 38,373 adults who had returned the baseline questionnaire and provided blood samples. Two controls were selected from the cohort for each case matched by age, sex, study area, date of blood drawn, and fasting time at blood donation. The odds ratio of colorectal cancer for plasma C-reactive protein was estimated using a conditional logistic regression model adjusted for pack-years of smoking, body mass index, alcohol consumption, physical exercise, and family history of colorectal cancer. The highest quartile group of plasma C-reactive protein was significantly associated with colorectal cancer compared with the lowest group (odds ratio, 1.6; 95% confidence interval, 1.1-2.5; P(trend) = 0.053). The association became clearer after excluding cases of rectal cancer (P(trend) = 0.041) and limiting colorectal cancer to the intramucosal type (P(trend) = 0.017). This association was unchanged after deletion of the first 2-year cases. In conclusion, plasma levels of C-reactive protein were associated with a subsequent risk of colon cancer. Inflammation may be involved at the early stage of colon tumor growth.     

Plasma folate and risk of colorectal cancer in a nested case-control study: the Japan Public Health Center-based prospective study

Objective There is some evidence that folate may prevent colorectal cancer by stabilizing DNA sufficiently and methylating DNA appropriately. Plasma folate is a good marker to assess folate status in the body, but it has not been adequately examined in prospective epidemiologic studies. We investigated the association between plasma folate and the risk of colorectal cancer in a nested case-control study. Methods During a 11.5-year follow-up, 375 newly diagnosed colorectal cancers were identified in a cohort of 38,373 adults who had returned their baseline questionnaires and provided blood samples. Two controls for each case were selected from the cohort. The odds ratios (OR) and 95% confidence intervals (CI) of colorectal cancer for plasma folate was estimated using the conditional logistic regression model adjusted for potential confounding factors. Results Plasma folate was not associated with the risk of colorectal cancer in either men or women, although a small reduction of OR in men was observed in the second (OR, 0.70; 95% CI, 0.37–1.3), the third (OR, 0.72; 95% CI, 0.38–1.3), and the highest quartiles (OR, 0.86; 95% CI, 0.45–1.6) without a dose–response relationship (P for trend 0.88). A similar association was observed in the risk of colon or rectal cancer. No statistical interaction with the risk of colorectal cancer was observed between plasma folate and alcohol consumption. Conclusion Our results did not support the hypothesis that a folate-rich status may prevent colorectal cancer, though that finding may be due to an insufficient number of folate-deficient subjects in our study population.     

Rice,bread, noodle and cereal intake and colorectal cancer in Japanese men and women: the Japan Public Health Center-based prospective Study (JPHC Study)

Background:

Colorectal cancer (CRC) incidence rate increased rapidly in Japan between the 1950s and 1990s. We examined the association between rice intake and CRC risk in comparison with bread, noodles and cereal among Japanese adults enrolled in the Japan Public Health Center-based prospective Study.

Methods:

A total of 73 501 Japanese men and women were followed-up from 1995 to 1999 until the end of 2008 for an average of 11 years. During 801 937 person-years of follow-up, we identified 1276 incident cases of CRC. Hazard ratios (HRs) and 95% confidence intervals (95% CIs) of CRC for rice, noodle, bread and cereal intake were calculated by Cox proportional hazards model.

Results:

Overall, no significant association was observed for the highest quartile of rice intake compared with the lowest and the risk of CRC and its subsites in men (HR, 0.77; 95% CI, 0.56–1.07) and women (HR, 1.10; 95% CI, 0.71–1.68). However, a non-significant inverse trend was observed between rice intake and rectal cancer in men. No clear patterns of association were observed in bread, noodle and cereal intake.

Conclusion:

Our findings suggest that the consumption of rice does not have a substantial impact on the risk of CRC in the Japanese population.     

Seaweed consumption and the risk of thyroid cancer in women: the Japan Public Health Center-based Prospective Study

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.     

Long-term antihypertensive drug use and risk of cancer: The Japan Public Health Center-based prospective study

Antihypertensive drugs have been reported as both promotors and suppressors of cancers and this relationship has been known for several decades. We examined a large-scale prospective cohort study in Japan to assess the relationship between long-term antihypertensive drug use, for 10 y, and carcinogenesis. We divided participants into 4 categories according to the period of antihypertensive drug use, and calculated the hazard ratios (HRs), 95% confidence intervals (CIs), and P trends using the Cox proportional hazard model. In all cancers, there was a significant difference in the medication period and the adjusted HR, as well as a significant difference in the P trend. Furthermore, more than 10 y use of antihypertensive drugs significantly increased the adjusted HR in colorectal cancer (multivariable HR: 1.18, 95% CI: 1.01-1.37 in the >10 y use group; P for trend = .033) and renal cancer (multivariable HR: 3.76, 95% CI: 2.32-6.10 in the 5-10 y use group; multivariable HR: 2.14, 95% CI: 1.29-3.56 in the >10 y use group; P for trend < .001). The highest adjusted HR in renal cancer among antihypertensive drug users was observed in the analysis performed on patients in which the outcomes were calculated from 3 y after the 10-y follow-up survey and by sex. A large-scale cohort study in Japan suggested that long-term use of antihypertensive drugs may be associated with an increased incidence of colorectal and renal cancer.     

Cigarette smoking and subsequent risk of lung cancer by histologic type in middle-aged Japanese men and women: the JPHC study

In order to update the findings of relative risk associated with cigarette smoking for lung cancer by histologic type in Japan, the data from a population-based cohort study of 91,738 men and women were analyzed. During 1990-1999, 422 lung cancer incident cases were identified. The relative risk for all incident cases associated with current smokers versus non-smokers was 4.5 [95% confidence interval (CI): 3.0-6.8] and 4.2 (95% CI: 2.4-7.2), for men and women, respectively. When divided by histologic type, relative risk for squamous cell carcinoma and small cell carcinoma was 12.7 (95% CI: 4.7-34.7) and 17.5 (95% CI: 4.9-62.1), while for adenocarcinoma it was 2.8 (95% CI: 1.6-4.9) and 2.0 (95% CI: 0.8-5.0) for men and women, respectively. We confirmed that the lung cancer risk in men rose with increasing cigarette smoking, especially the duration of smoking among current smokers and decreased after the cessation of smoking among former smokers. Unlike the US or European countries, the relative risk did not increase in this updated study, compared with previous studies in 1960s to 1990s in Japan either for all incident cases or for specific histologic types and the magnitude of relative risks was substantially lower than that observed in the US or European countries, especially for adenocarcinoma.     

Cigarette smoking and the risk of colorectal cancer among men: a prospective study in Japan.

The association between cigarette smoking and the risk of colorectal cancer remains controversial. We examined this association using a population-based prospective cohort study in Miyagi, Japan. In 1990, we delivered a self-administered questionnaire on cigarette smoking and other health habits to 25 279 men who were 40-64 years of age and lived in 14 municipalities of Miyagi Prefecture. A total of 22 836 men responded (90.3% response rate). During 7 years of follow-up (158 376 person-years), we identified 188 patients of colorectal cancer. Relative risks and 95% confidence intervals were estimated by the Cox proportional-hazards regression analysis with adjustment for potential confounders. The multivariate-adjusted relative risks (95% confidence interval) of colorectal cancer for past smokers and current smokers compared with those who had never smoked were 1.73 (1.04-2.87) and 1.47 (0.93-2.34), respectively. Among current smokers, both a higher number of cigarettes smoked per day and an earlier age at which smoking had started were associated with a significant linear increase in risk (P for trend <0.05). Our findings are consistent with the hypothesis that cigarette smoking is associated with a higher risk of colorectal cancer in men.     

Alcohol consumption and risk of prostate cancer in middle-aged men

Alcohol consumption is a modifiable lifestyle factor that may affect prostate cancer risk. Alcohol alters the hormonal milieu and contains chemical substances such as flavonoids (red wine), which may alter tumor cell growth. Data from a population-based case-control study in King County, WA, were utilized to evaluate the association of alcohol consumption with prostate cancer in middle-aged men. A total of 753 newly diagnosed prostate cancer cases, 40-64 years of age, participated in the study. Seven hundred three control subjects, frequency matched to cases by age, were selected through random digit dialing. All participants completed an in-person interview on lifetime alcohol consumption and other risk factors for prostate cancer. Logistic regression models were used to estimate odds ratios (OR) and assess significance (95% confidence intervals [CI]). All tests of statistical significance were two-sided. No clear association with prostate cancer risk was seen for overall alcohol consumption. Each additional glass of red wine consumed per week showed a statistically significant 6% decrease in relative risk (OR = 0.94; 95% CI = 0.90-0.98), and there was evidence for a decline in risk estimates across increasing categories of red wine intake (trend p = 0.02). No clear associations were seen for consumption of beer or liquor. Our present study suggests that consumption of beer or liquor is not associated with prostate cancer. There may be, however, a reduced relative risk associated with increasing level of red wine consumption. Further research is needed to evaluate the potential negative association between red wine intake and prostate cancer risk.     

Coffee consumption and risk of colorectal cancer in a population-based prospective cohort of Japanese men and women

We prospectively examined the association between coffee consumption and the risk of developing colorectal cancer in a large population-based cohort study (the JPHC Study) of Japanese men and women. Data were analyzed from a population-based cohort of 96,162 subjects (46,023 men and 50,139 women). A total of 1,163 incident colorectal cancers were identified during the follow-up period, including 763 cases of colon cancer and 400 of rectal cancer. We observed a significant inverse association between coffee consumption and the risk of developing invasive colon cancer among women. Compared with those who almost never consumed coffee, women who regularly consumed 3 or more cups of coffee per day had a RR of 0.44 (95% CI = 0.19-1.04; p for trend = 0.04) after adjustment for potential confounding factors. However, no significant association was found for rectal cancer in women. In men, no significant decrease was observed in any colorectal cancer site. Further, additional analyses on the association of green tea consumption with colorectal cancer risk found no significant association in men or women. These findings suggest that coffee consumption may lower the risk of colon cancer among Japanese women.     

Smoking and risk of premature death among middle-aged Japanese: ten-year follow-up of the Japan Public Health Center-based prospective study on cancer and cardiovascular diseases (JPHC Study) cohort I.

To update the evidence on the association between smoking and mortality, we analyzed data from a population-based prospective study in Japan. In total, 19950 men and 21534 women aged 40 - 59 who reported their smoking history and had no serious disease at baseline survey were followed. During 1990 - 1999, 1014 men and 500 women died. Smokers were associated with an unhealthy lifestyle. Relative risks (RRs) for selected cause of death due to smoking were slightly attenuated by adjusting for possible confounding factors. Age- and area-adjusted RRs of male current smokers compared with never smokers were 1.66 (95% confidence intervals (CI): 1.40, 1.95) for all causes, 1.69 (1.31, 2.18) for all cancers, 1.67 (1.20, 2.34) for all circulatory system disease, and 1.63 (1.24, 2.15) for other causes, while those of females were 2.03 (1.52, 2.73), 2.06 (1.35, 3.15), 2.99 (1.75, 5.11), 1.31 (0.69, 2.51), respectively. After adjusting for multivariate variables, the corresponding RRs of male smokers were 1.55 (1.29, 1.86), 1.61 (1.20, 2.15), 1.41 (0.97, 2.03), and 1.61 (1.17, 2.19), against 1.89 (1.36, 2.62), 1.83 (1.14, 2.95), 2.72 (1.45, 5.07), and 1.39 (0.71, 2.73) for females. Twenty-two percent of death from all causes, 25% of all cancer, and 17% of all circulatory system disease deaths, could be attributed to cigarette smoking in males, and 5%, 4%, and 11% in females, respectively. Cumulative dose as indicated by pack-years was clearly associated with cancer death. These findings provided information as to the quantitative risk for premature death due to smoking among middle-aged Japanese men and women, and showed that the elevated risk was not explained by the unhealthy lifestyle of smokers.     

Dietary consumption of antioxidant vitamins and subsequent lung cancer risk: The Japan Public Health Center‐based prospective study

While many epidemiological studies have studied the association between lung cancer risk and fruits and vegetable consumption (the major sources of antioxidant vitamins), only a few have investigated the direct association with antioxidants in consideration of cancer subtypes and smoking status. Here, we examined the association between consumption of antioxidant vitamins and lung cancer risk in one of the largest prospective cohort studies in Japan. We investigated the association of dietary antioxidant vitamins intake, namely retinol, vitamin C, vitamin E, α‐carotene, and β‐carotene and subsequent incidence of lung cancer among 38,207 men and 41,498 women in the Japan Public Health Center‐based prospective study. Cox proportional hazard regression was performed with adjustment for potential confounders and by strata of cancer subtypes and smoking status. Antioxidant and other dietary intakes were assessed using a food frequency questionnaire (FFQ). During 1,233,096 person‐years of follow‐up between 1995 and 2013, a total of 1,690 lung cancer cases were newly diagnosed. In a multivariate regression model, while higher retinol intake was positively associated with overall lung cancer risk in men (HR 1.26; 95% CI 1.05–1.51; p_trend = 0.003), the estimates were more evident with small cell carcinoma (HR 1.92; 95% CI 1.13–3.24; p_trend < 0.001). Null associations were observed for other antioxidant vitamins. Our prospective study suggests that higher consumption of retinol may be associated with an increased risk of lung cancer in men, especially with small cell carcinoma, although confirmation is required.     

Association between meat and saturated fatty acid intake and lung cancer risk: The Japan Public Health Center-based prospective study

Red meat or saturated fatty acid (SFA) intake has been reported to increase lung cancer (LC) risk in several western countries. However, in Asia, studies on the relationship between meat and SFA intake with LC incidence are still relatively insufficient, and their conclusions are inconsistent. We investigated the association of meat and SFA intake with LC incidence in a population-based prospective cohort study in Japan. Cox regression was used to estimate the hazard ratio (HR) and 95% confidence interval (CI) for LC risk according to meat intake and SFA intake. A total of 73 187 participants (32 934 men and 40 253 women) aged 45 to 74 years participated in our study. During the follow-up period of 1 151 839 person-years (median, 16.0 year) from 1995 to 2013 for Cohort I and from 1998 to 2013 for Cohort II, 1315 (901 men and 414 women) newly diagnosed cases of LC were identified. In men, we found an adverse association between total red meat intake (HR and 95% CI: 1.25 [1.02-1.53]; P_trend = .008) and LC risk. Additionally, borderline statistically significant elevated risks of LC were seen with high intake of unprocessed red meat and processed red meat. However, no positive association between total red meat intake and LC risk was observed in women. In contrast, poultry and fish intake were not associated with LC risk in either men or women. We concluded that a high total intake of total red meat was associated with moderately elevated LC risk in men.     

Dietary arsenic intake and subsequent risk of cancer: the Japan Public Health Center-based (JPHC) Prospective Study

Purpose

Arsenic is a known human carcinogen and has been linked to adverse health outcomes, including cancer. However, the effects of arsenic exposure from food on health are still unknown. We researched to examine the association between arsenic exposure from food and incidence of cancer in a Japanese population.

Methods

We conducted a population-based prospective study in 90,378 Japanese men and women aged 45–74 years. Participants responded to a validated questionnaire that included 138 food items. We estimated dietary arsenic intake from 12 food groups (75 items) based on the questionnaire data. During 11 years of follow-up, 7,002 cancer cases were identified. Hazard ratios (HRs) and 95 % confidence intervals (CIs) for cancer were calculated by Cox proportional hazards modeling.

Results

Total arsenic and inorganic arsenic showed no association with the risk of total cancer in both men and women. Total arsenic and inorganic arsenic intake tended to be associated with an increased risk of lung cancer in men. In particular, these positive associations were strengthened in currently smoking men, with HRs (95 % CI) in the highest categories of arsenic and inorganic arsenic intake compared with the lowest of 1.29 (95 % CI = 1.03–1.61) and 1.36 (95 % CI = 1.09–1.70), respectively. We also detected an interaction between arsenic and inorganic arsenic intake and smoking status in men (p _interaction < 0.01 and 0.07, respectively).

Conclusion

A significant dose–response trend was seen in the association of arsenic and inorganic intake with lung cancer risk in currently smoking men.     

Alcohol consumption and the risk of cancer in Japanese men: the Miyagi cohort study.

The objective of this study was to investigate the association between alcohol consumption and the risk of total cancer, and to estimate the proportion of total cancer attributable to drinking habit in Japanese men. From June through August 1990, a total of 21 201 Japanese men completed a self-administered questionnaire on various health habits, including alcohol consumption. During 153 389 person-years of follow-up through December 1997, we identified a total of 882 cases of cancer. We used Cox proportional hazards regression to estimate the relative risk of total cancer according to categories of alcohol consumption. The risk for total cancer was significantly higher in ex-drinkers than never-drinkers. There was a dose-response relationship between the amount of alcohol consumed and the risk of total cancer among current drinkers: multivariate RRs in reference to never-drinkers (95% confidence intervals (CI)) were 1.1 (0.8-1.3), 1.3 (1.0-1.7), and 1.3 (1.1-1.7) in current drinkers who consumed less than 22.8 g, 22.8-45.5 g, 45.6 g or more alcohol per day, respectively (P for trend <0.001). Estimated 17.9% (95% CI 3.1-30.5) of total cancer risk was attributable to drinking habit. In our findings, approximately 20% of the total cancer cases in Japanese men may be prevented by alcohol control.     

Alcohol consumption and breast cancer risk in Japanese women: the Miyagi Cohort study

Alcohol consumption is known to be a risk factor for breast cancer in Western countries, but few epidemiologic data have been available in Japan. This population-based prospective cohort study evaluated the associations of alcohol consumption with breast cancer risk in a Japanese population. A total of 19,227 women aged 40–64 years were followed from 1990 to 2003. During 246,703 person-years of follow-up, 241 breast cancer cases were identified. Hazard ratios (HRs) were estimated by the Cox proportional-hazard regression model. After adjustment for potential risk factors of breast cancer and nutritional factors, the HR and 95% confidence interval (CI) for current drinkers was 1.00 (0.74–1.34) compared with never drinkers. According to the amount of alcohol intake per day, a higher amount (≥15.0 g/day) had no significant relation to breast cancer risk (HR = 0.87, 95% CI: 0.40–1.91; P for trend = 0.85). Age upon starting to drink, and the frequency of drinking, were not associated with breast cancer risk. In analysis stratified according to exogenous female hormone use, a higher alcohol intake (≥15.0 g/day) was associated with an increased risk of breast cancer among hormone users (HR = 1.67, 95% CI: 0.17–16.73); however, this was not statistically significant. Stratification according to folate intake with energy adjustment (<219, ≥219 μg/day) found that breast cancer risk tended to increase with increasing alcohol consumption among women with a low intake of folate (P for trend = 0.09). Our findings suggest that alcohol consumption has no overall effect on breast cancer risk among Japanese women, whereas nutritional factors such as folate intake may modify the alcohol-breast cancer risk relationship.     

Dietary patterns and prostate cancer risk in Japanese: the Japan Public Health Center-based Prospective Study (JPHC Study)

Purpose

The development of prostate cancer may be impacted by environmental factors, including diet. The aim of this study was to evaluate the association between dietary patterns and risk of prostate cancer in a large prospective cohort study among Japanese men.

Methods

A total of 43,469 men who participated in the Japan Public Health Center-based Prospective Study were followed from 1995 to 1998 to the end of 2012, during which 1,156 cases of prostate cancer were newly identified. Dietary intake was assessed using a validated food frequency questionnaire in the 5-year follow-up survey.

Results

Three major dietary patterns were derived using exploratory factors analysis: prudent, westernized, and traditional dietary patterns. The westernized dietary pattern was associated with a higher risk of total prostate cancer (HR: 1.22; 95% CI 1.00–1.49; p trend?=?0.021), localized cancer (HR: 1.24; 95% CI 0.97–1.57; p trend?=?0.045), and advanced cancer (HR: 1.23; 95% CI 0.82–1.84; p trend?=?0.233). The prudent dietary pattern was associated with a lower risk of total and localized prostate cancer, with respective multivariable HRs for the highest and lowest quintiles of 0.71 (95% CI 0.50–1.02; p trend?=?0.037) and 0.63 (95% CI 0.38–1.03; p trend?=?0.048) among subjects detected by subjective symptoms. No association was found between the traditional dietary pattern and prostate cancer risk among our subjects.

Conclusion

Our results suggest that a western-style diet may lead to a higher risk of prostate cancer in the total population, whereas the prudent diet contributes to a lower risk among subjects detected by subjective symptoms.