Dietary Consumption of Antioxidant Vitamins in Relation to Prostate Cancer Risk in Japanese Men: The Japan Public Health Center-based Prospective Study

BACKGROUND

Many epidemiological studies have investigated dietary intake of antioxidant vitamins in relation to prostate cancer risk in Western countries, but the results are inconsistent. However, few studies have reported this relationship in Asian countries.

METHODS

We investigated the association between intake of vitamins, including lycopene, α-carotene, β-carotene, vitamin C, vitamin E, with prostate cancer risk in the Japan Public Health Center-based Prospective (JPHC) study. 40,720 men without history of cancer finished the food frequency questionnaire (FFQ) and were included in the study. Hazard ratios (HRs) and 95% confidence intervals (CIs) of prostate cancer risk were calculated according to the quintiles of energy-adjusted intake of vitamins using Cox models.

RESULTS

After an average of 15.2 years (617,599 person-years in total) of follow-up, 1,386 cases of prostate cancer were identified, including 944 localized cases and 340 advanced cases. No associations were observed in consumption of antioxidant vitamins, including α-carotene, β-carotene, vitamin C, and vitamin E, and prostate cancer risk. Although higher lycopene intake was associated with increased risk of prostate cancer (highest vs lowest quintile, HR 1.24; 95% CI, 1.04-1.47; P for trend = 0.01), there was a null association of lycopene intake with risk of prostate cancer detected by subjective symptoms (HR 1.12; 95% CI, 0.79-1.58; P for trend = 0.11).

CONCLUSION

Our study suggested no association between antioxidant intake of vitamins and prostate cancer risk.

Associations between dairy intake and mortality due to all-cause and cardiovascular disease: the Japan Public Health Center-based prospective study

BACKGROUND

Some studies have investigated the relation between dairy products and mortality, but with inconsistent results.

OBJECTIVE

We examined the association between the consumption of dairy products and the risk of all-cause, cancer-related, and cardiovascular disease (CVD)-related mortality.

METHODS

From the Japan Public Health Center-based Prospective (JPHC) study, 43,117 males and 50,193 females with no history of cancer or CVD finished the food frequency questionnaire (FFQ) and were included in the study. Intake of dairy products was assessed using the FFQ and adjusted for total energy by using the residual method. We used multivariate Cox proportional hazard models to calculate hazard ratios (HRs) and 95% confidence intervals (95% CIs) for mortality risk in males and females.

RESULTS

14,211 deaths in males and 9547 deaths in females from all causes were identified during an average follow-up of 19.3 years. For males, total dairy consumption was nonlinearly and significantly associated with lower risk of mortality from all causes [the third quartile, HR = 0.87 (0.83, 0.91), the fourth quartile, HR = 0.89 (0.85, 0.94), P for nonlinearity < 0.001] and CVD [the third quartile, HR = 0.77 (0.70, 0.85), the fourth quartile, HR = 0.78 (0.70, 0.86), P for nonlinearity < 0.001]. Milk and fermented milk intake were inversely associated with all-cause and CVD-related mortality in males. Cheese consumption was inversely associated with CVD-related mortality among males. There was no association between total dairy intake and mortality risk among females.

CONCLUSION

For Japanese people, consumption of dairy products was associated with a decreased risk of mortality from all-cause and cardiovascular diseases among males.

Association of sugary drink consumption with all-cause and cause-specific mortality: the Japan Public Health Center-based Prospective Study

BACKGROUND

Few epidemiologic studies have assessed the associations of sugary drink consumption with mortality outcomes among Asian populations.

METHODS

This study included 70,486 participants in the Japan Public Health Center-based Prospective Study at the age of 45-74 years in 1995-1999. A validated food frequency questionnaire was used to assess the consumption of sugary drinks. We estimated the risk of total and cause-specific mortality associated with sugary drink consumption using Cox proportional hazards regression model.

RESULTS

Mean follow-up was 17.1 years, during which 11,811 deaths were documented. Sugary drink consumption was associated with higher total mortality, with multivariate HR of 1.06 (95% CI 1.00-1.13) for quintile 3, 1.07 (95% CI 1.01-1.13) for quintile 4, and 1.15 (95% CI 1.09-1.22) for quintile 5, compared with quintile 1 (P < 0.001 for trend). Additionally, positive associations with cause-specific mortality were observed, including death from circulatory system diseases (quintile 5 vs quintile 1; HR, 1.23; 95% CI 1.09-1.38) and heart disease (quintile 5 vs quintile 1; HR, 1.35; 95% CI 1.14-1.60).

CONCLUSION

In this large Japanese prospective study, sugary drink consumption was associated with all-cause and cause-specific mortality.

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

PURPOSE

Although 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.

METHODS

A 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.

RESULTS

During 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.

CONCLUSIONS

Compared 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.

Coffee and green tea consumption and subsequent risk of acute myeloid leukemia and myelodysplastic syndromes in Japan

Although coffee and green tea are suggested to reduce the risk of some types of cancers, only a few epidemiological studies have investigated their effect on the risk of acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS). Here, we investigated the association of coffee and green tea consumption and the risk of AML and MDS in a large-scale population-based cohort study in Japan. A total of 95,807 Japanese subjects (45,937 men and 49,870 women; age 40-69 years at baseline) were followed to the end of 2012, for an average of 18 years. Hazard ratios (HRs) and 95% confidence intervals (95% CIs) for the association between coffee and green tea consumption at baseline and the risk of AML and MDS were assessed using a Cox proportional hazards model with adjustment for potential confounders. During 1,751.956 person-years, we identified 85 AML cases and 70 MDS cases. Our findings showed no significant association between coffee consumption and the risk of AML, or between green tea consumption and the risk of AML or MDS. In contrast, we observed a decreasing dose-response relationship between coffee consumption and the risk of MDS among men (almost none: reference, 1-4 times/week: HR = 0.83, 95% CI: 0.43-1.62; ≥1cups/day: HR = 0.47, 0.22-0.99, p for trend = 0.049). Stratified analysis by smoking status suggested that the observed relative risk for AML and MDS of coffee drinkers relative to non-coffee drinkers might be due to residual confounding by smoking. These findings deserve further investigation in future studies.

Smoking and subsequent risk of leukemia in Japan: The Japan Public Health Center-based Prospective Study

BACKGROUND

Cigarette smoking has been reported to be associated with an increased risk of leukemia. Most epidemiological evidence on the association between cigarette smoking and leukemia risk is from studies conducted in Western populations, however, and evidence from Asian populations is scarce.

METHODS

We conducted a large-scale population-based cohort study of 96,992 Japanese subjects (46,493 men and 50,499 women; age 40-69 years at baseline) with an average 18.3 years of follow-up, during which we identified 90 cases of acute myeloid leukemia (AML), 19 of acute lymphoblastic leukemia (ALL), and 28 of chronic myeloid leukemia (CML). Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using a Cox regression model adjusted for potential confounders.

RESULTS

When we adjusted for age, sex, and study area, our findings showed no significant association or increasing dose-response relationship between risk of AML and cigarette smoking overall. However, after further adjustment for body mass index and occupation, current smokers with more than 30 pack-years of cigarette smoking had a significantly increased risk of AML compared to never smokers among men (HR 2.21; 95% CI, 1.01-4.83). This increased risk was not clear among women.

CONCLUSIONS

Our results suggest that cigarette smoking increases the risk of AML in Japanese men. The associations of smoking with AML among women, and with CML and ALL among men and women, should be assessed in future studies.

Association between Chlamydophila pneumoniae infection and risk of coronary heart disease for Japanese: the JPHC study

BACKGROUND

Chlamydophila pneumoniae infection is considered a risk factor for atherosclerosis and coronary heart disease in western countries. However, evidence of it being a risk for Japanese is very limited because of a lower risk of coronary heart disease than for western people. The aim of this study was to examine further the association between C. pneumoniae infection and risk of coronary heart disease in Japanese.

METHODS

We conducted a nested case-control study of 49,011 Japanese men and women who participated in The Japan Public Health Center (JPHC) study. By the end of 2004, 196 cases of coronary heart disease and 155 cases of myocardial infarction had been documented among the participants. Two controls were selected for each case. For these subjects, we examined the association between serum anti C. pneumoniae IgA and IgG on the one hand and risk of coronary heart disease on the other.

RESULTS

Concentration of C. pneumoniae IgA antibody was positively associated with risk of coronary heart disease and more specifically myocardial infarction. Subjects with the highest quartile of IgA antibody showed 2.29 (95%CI, 1.21-4.33) times higher risk of coronary heart disease and 2.58 (95%CI, 1.29-5.19) times higher risk of myocardial infarction than those with lowest quartile. However, no such association was detected for IgG antibody.

CONCLUSION

C. pneumoniae infection was found to be positively associated with risk of coronary heart disease.

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.