Obesity/weight gain and breast cancer risk: findings from the Japan collaborative cohort study for the evaluation of cancer risk.

BACKGROUND: We analyzed data from the Japan Collaborative Cohort Study (36 164 women aged 40-79 years at baseline in 1988-1990 with no previous diagnosis of breast cancer and available information on weight and height) to examine the association between baseline body mass index (BMI)/weight gain from age 20 years and breast cancer risk in a non-Western population. METHODS: The participants were followed prospectively from enrollment until 1999-2003 (median follow-up: 12.3 years). During follow-up, breast cancer incidence was mainly confirmed through record linkage to population-based cancer registries. A Cox proportional hazards model was used to calculate hazard ratios (HRs) and 95% CIs for the association between breast cancer risk and body size. RESULTS: In 397 644.1 person-years of follow-up, we identified 234 breast cancer cases. Among postmenopausal women, the adjusted HR increased with BMI, with a significant linear trend (P < 0.0001). Risk was significantly increased among women with a BMI of 24 or higher (HR: 1.50, 95% CI: 1.09-2.08 for BMI of 24-28.9, and 2.13, 1.09-4.16 for BMI ≥ 29) as compared with women with a BMI of 20 to 23.9. Weight gain after age 20 years and consequent overweight/obesity were combined risk factors for postmenopausal breast cancer risk. This combined effect was stronger among women aged 60 years or older. However, the HRs were not significant in premenopausal women. CONCLUSIONS: Our findings support the hypothesis that weight gain and consequent overweight/obesity are combined risk factors for breast cancer among postmenopausal women, particularly those aged 60 years or older.

Body mass index and weight change during adulthood are associated with increased mortality from liver cancer: the JACC Study.

BACKGROUND: We investigated the association of baseline body mass index (BMI) and weight change since age 20 years with liver cancer mortality among Japanese. METHODS: The data were obtained from the Japan Collaborative Cohort Study for Evaluation of Cancer Risk (JACC Study). A total of 31 018 Japanese men and 41 455 Japanese women aged 40 to 79 years who had no history of cancer were followed from 1988 through 2009. RESULTS: During a median 19-year follow-up, 527 deaths from liver cancer (338 men, 189 women) were documented. There was no association between baseline BMI and liver cancer mortality among men or men with history of liver disease. Men without history of liver disease had multivariable hazard ratios (HR) of 1.95 (95%CI, 1.07-3.54) for BMI less than 18.5 kg/m(2) and 1.65 (1.05-2.60) for BMI of 25 kg/m(2) or higher, as compared with a BMI of 21.0 to 22.9 kg/m(2). BMI was positively associated with liver cancer mortality among women and women with history of liver disease. Weight change since age 20 years was positively associated with liver cancer mortality among women regardless of history of liver disease. Women with history of liver disease had a multivariable HRs of 1.96 (1.05-3.66) for weight gain of 5.0 to 9.9 kg and 2.31 (1.18-4.49) for weight gain of 10 kg or more, as compared with weight change of -4.9 to 4.9 kg. CONCLUSIONS: Both underweight (BMI <18.5 kg/m(2)) and overweight (BMI ≥25 kg/m(2)) among men without history of liver disease, and weight gain after age 20 (weight change ≥5 kg) among women with history of liver disease, were associated with increased mortality from liver cancer.

Cohort profile of the Japan Collaborative Cohort Study at final follow-up.

The Japan Collaborative Cohort Study for Evaluation of Cancer Risk (JACC Study) was established in the late 1980s to evaluate the risk impact of lifestyle factors and levels of serum components on human health. During the 20-year follow-up period, the results of the study have been published in almost 200 original articles in peer-reviewed English-language journals. However, continued follow-up of the study subjects became difficult because of the retirements of principal researchers, city mergers throughout Japan in the year 2000, and reduced funding. Thus, we decided to terminate the JACC Study follow-up at the end of 2009. As a final point of interest, we reviewed the population registry information of survivors. A total of 207 (0.19%) subjects were ineligible, leaving 110 585 eligible participants (46 395 men and 64 190 women). Moreover, errors in coding date of birth and sex were found in 356 (0.32%) and 59 (0.05%) cases, respectively, during routine follow-up and final review. Although such errors were unexpected, their impact is believed to be negligible because of the small numbers relative to the large total study population. Here, we describe the final cohort profile at the end of the JACC Study along with selected characteristics of the participants and their status at the final follow-up. Although follow-up of the JACC Study participants is finished, we will continue to analyze and publish study results.

Relationship of hobby activities with mortality and frailty among community-dwelling elderly adults: results of a follow-up study in Japan.

BACKGROUND: The proportion of Japanese adults aged 65 years or older is predicted to increase; thus, it is becoming more important to identify factors that influence health status among elderly adults in Japan. We conducted a follow-up study of community-dwelling elderly adults to assess the relationship of hobby activities with mortality and incident frailty. METHODS: We randomly selected 3583 individuals aged 65 to 84 years from the residential registries of 7 study areas in Hokkaido, Japan in August 2007. Among them, 1955 (54.6%) returned completed questionnaires with written informed consent by mail. The baseline assessment questionnaire comprised questions on current and past involvement in hobby activities, self-perceived health status, smoking and drinking habits, and body height and weight. Questions on hobby activities were from 4 categories: solitary physical, group physical, solitary cultural, and group cultural activities. We later conducted a follow-up survey of the participants to ascertain all-cause mortality and incident frailty. A Cox proportional hazards model was used for analysis of data from September 2007 to May 2010. RESULTS: After adjusting for potential confounders, the risk of incident frailty among respondents participating in solitary physical activities was significantly lower than in those who did not participate in such activities (hazard ratio = 0.57; 95% CI 0.33, 0.99). Furthermore, the risk of incident frailty among respondents taking part in group cultural activities was significantly lower than in those who did not participate in such activities (0.41; 0.19, 0.87). CONCLUSIONS: These findings may be important for programs that seek to promote good health among elderly adults.

Effect of physical activity on breast cancer risk: findings of the Japan collaborative cohort study.

PURPOSE: This study aimed to examine prospectively the association between physical activity and breast cancer risk in a non-Western population. METHODS: We analyzed data from the Japan Collaborative Cohort Study, which included 30,157 women, ages 40 to 69 years at baseline (1988-1990), who reported no previous history of breast cancer, and provided information on their walking and exercise habits. The subjects were followed prospectively from enrollment until 2001 (median follow-up period, 12.4 years). Breast cancer incidence during this period was confirmed using records held at population-based cancer registries. The Cox proportional hazards model was used to estimate the hazard ratio (HR) for the association of breast cancer incidence with physical activity. RESULTS: During the 340,055 person-years of follow-up, we identified 207 incident cases of breast cancer. The most physically active group (who walked for > or = 1 hour per day and exercised for > or = 1 hour per week) had a lower risk of breast cancer (HR, 0.45; 95% confidence interval, 0.25-0.78) compared with the least active group after adjusting for potential confounding factors. The inverse association of exercise on breast cancer was stronger among those who walked for > or = 1 hour per day than those who walked for <1 hour per day (P = 0.042). These results were not significantly modified by menopausal status or body mass index (BMI). CONCLUSIONS: Our analysis provided evidence that physical activity decreased the risk of breast cancer. Walking for 1 hour per day and undertaking additional weekly exercise both seemed to be protective against breast cancer, regardless of menopausal status or BMI.

Relationship between hepatocellular carcinoma and impaired glucose tolerance among Japanese.

BACKGROUND/AIMS: Both the incidence of diabetes mellitus (DM) and mortality from Hepatocellular carcinoma (HCC) are increasing in Japan. As the association of overall cancer and HCC with impaired glucose tolerance (IGT) has been studied rarely in the world including Japan, this study assessed their associations using cohort data of Hokkaido, Japan. METHODOLOGY: After getting ethical consent, this study included 908 men and 1,081 women aged 30-77 years during 1977-78 and collected detailed information using the baseline survey. The subjects were followed until 2002 and deaths were recorded using ICD-9. Classifying them into three groups of diabetes status namely DM, IGT, and normal, the relative risk (RR) of mortality was estimated by diabetes status using multivariate Cox model. RESULTS: This study revealed no association between overall cancer and diabetes status. However, the RR of mortality from HCC was about 11 times (HR= 10.8, 95%CI: 1.3-92.5) higher in IGT compared with normal group. DM group also showed higher risk of mortality than normal group. CONCLUSIONS: HCC mortality was significantly high among IGT group. However, as the results of the study were based on small data, further studies with large cohort are needed to address the association of IGT with overall cancer and HCC mortality in Japan.

Roles and causes of abnormal DNA methylation in gastrointestinal cancers.

Evidence now suggests that epigenetic abnormalities, particularly altered DNA methylation, play a crucial role in the development and progression of human gastrointestinal malignancies. Two distinct DNA methylation abnormalities are observed together in cancer. One is an overall genome-wide reduction in DNA methylation (global hypomethylation) and the other is regional hypermethylation within the CpG islands of specific gene promoters. Global hypomethylation is believed to induce proto-oncogene activation and chromosomal instability, whereas regional hypermethylation is strongly associated with transcriptional silencing of tumor suppressor genes. To date, genes involved in regulation of the cell cycle, DNA repair, growth signaling, angiogenesis, and apoptosis, are all known to be inactivated by hypermethylation. Recently developed techniques for detecting changes in DNA methylation have dramatically enhanced our understanding of the patterns of methylation that occur as cancers progress. One of the key contributors to aberrant methylation is aging, but other patterns of methylation are cancer-specific and detected only in a subset of tumors exhibiting the CpG island methylator phenotype (CIMP). Although the cause of altered patterns of DNA methylation in cancer remains unknown, it is believed that epidemiological factors, notably dietary folate intake, might strongly influence DNA methylation patterns. Recent studies further suggest that polymorphisms of genes involved in folate metabolism are causally related to the development of cancer. Identifying epidemiological factors responsible for epigenetic changes should provide clues for cancer prevention in the future.

Risk factors for multiple myeloma: evidence from the Japan Collaborative Cohort (JACC) study.

This study assessed the association of multiple myeloma (MM) with age, body mass index (BMI, kg/m(2)), physical activity, occupational history, and medical history for a Japanese cohort of 46,157 men and 63,541 women aged 40-79 years followed during 1988-2003 years. Cox proportional hazard model was mainly used to estimate the age and sex adjusted hazard ratio (HR) of MM including 95% confidence interval (CI) for both sexes. Same model, adjusted for age, was also used for each sex. In total, 98 MM deaths (men=49 and women=49) was observed for both sexes. Higher age groups (60-69 and 70-79 years) experienced significantly higher unadjusted HR of MM than the age group of 40-49 years. Men revealed significantly higher age-adjusted MM than women (HR=1.5; 95% CI=1.0-2.2). For both sexes, higher BMI of >or=30 kg/m(2)) (HR=2.8; 95% CI=1.0-7.7), walking

Site-specific cancer risk due to diabetes mellitus history: evidence from the Japan Collaborative Cohort (JACC) Study.

The study examined the association of diabetes mellitus (DM) history with total and common site-specific cancers using a large cohort of 23,378 men and 33,503 women, extracted from 127,477 healthy participants of the JACC Study who were aged 40-79 years and living in 24 municipalities in Japan. At enrollment during 1988-90, each subject completed a self-administered questionnaire including items for age, sex, body mass index (BMI), smoking, drinking, past history of DM and cancer. Adjusting for age, BMI, smoking, and drinking in the Cox's proportional hazard model, incidence rate ratios (IRR) with 95% confidence intervals (95%CIs) were estimated for both sexes. During the follow-up period, total cancers and site-specific cancers were identified. A history of DM was reported by 7.5% of men and 4.6% of women. DM significantly increased the risk of liver cancer for both men (IRR=2.30; 95%CI=1.47-3.59) and women (IRR=2.70; 95%CI=1.20-6.05). Significant increased and reduced risk due to DM for men were also found for non-Hodgkin lymphoma (IRR=2.77; 95%CI=1.04-7.38) and stomach cancer (IRR=0.67; 95%CI=0.46-0.99) respectively. For females, a reduced risk of stomach cancer due to DM (IRR=0.49; 95%CI=0.23-1.04) was also revealed. Since a history of DM here demonstrated significant associations with some site-specific cancers, their relationships should be studied further in Japan for validation.

Risk of endometrial cancer mortality by ever-use of sex hormones and other factors in Japan.

OBJECTIVES: To examine associations of ever-use of sex hormones (EUSH) and other factors with endometrial cancer (EC) mortality through a nation-wide Japan Collaborative Cohort Study. METHODS: A total of 63,541 women aged 40-79 years, enrolled in 1988-90 from 45 municipalities of Japan, were followed until 2003 to record their vital status. Using baseline data, the Cox proportional hazard model (age adjusted and multivariate) was used to estimate the hazard ratio (HR) and 95% confidence interval (CI) for EC mortality by selected factors, including EUSH. Bivariate analysis was also conducted to establish associations between EUSH and other factors. RESULTS: The mortality rate from EC was 2.6 per 100,000 person-years during the mean follow-up period of 13.3 years. Prevalence rate of EUSH was 5.2%. Significantly increased risk of EC mortality was found for EUSH with both age adjusted (HR=6.43, 95%CI=2.10-19.67) and multivariate (HR=5.33; 95%CI=1.51-18.82) analyses. Bivariate analysis indicated that history of diabetes mellitus, smoking, drinking, and age at first delivery were positively associated with EUSH, whereas age, number of delivery, number of pregnancy, and age at menarche demonstrated inverse links. CONCLUSIONS: Our results imply that EUSH may increase the risk of EC mortality among Japanese women. However, further studies with more deaths are needed to validate the results.

Magnitude of arsenic toxicity in tube-well drinking water in Bangladesh and its adverse effects on human health including cancer: evidence from a review of the literature.

Only after a decade from 1993, arsenic contamination of groundwater in Bangladesh has been reported as the biggest arsenic catastrophe in the world. It is a burning public health issue in this country. More than 50 percent of the total population is estimated at risk of contamination. Already thousands of people have been affected by the disease arsenicosis. Many more may be on the way to manifest lesions in future. We conducted a review of previous studies and published articles including MEDLINE database on this issue. We found that 59 districts out of 64 have been already affected by arsenic in underground drinking water, where this particular source of drinking water is the main source for 97 percent of the rural people. The water is unfortunately now a great threat for the human being due to high level of arsenic. Continuous arsenic exposure can lead people to develop arsenicosis, which in turn elevates the risk of cancer. Skin lesions are the most common manifestations in arsenicosis patients. Relatively poor rural people and other socio-economically disadvantaged groups are more affected by this exposure. Until now cancer patients have been relatively limited in Bangladesh. One of the reasons may be that several years are needed to show cancer manifestations from the beginning of arsenic exposure. But it is suspected that after some years a large number of patients will appear with cancer in different sites for arsenic exposure in drinking water. Various studies have been conducted in arsenic affected countries - notably in Argentina, Chile, China, Japan, and Taiwan -to find the potential of arsenic exposure to cause development of cancer. Among the arsenic related cancers, liver, lung, skin, bladder and kidney cancers are reported to be prevalent in these countries. Unfortunately no scientific study has been yet conducted in Bangladesh to find the relationship between arsenic exposure and cancers in different sites of the body. So our aim is to conduct an ecological as well as a case-control study in the country in the future.

Dietary habits and cancer mortality among middle aged and older Japanese living in hokkaido, Japan by cancer site and sex.

Dietary factors are thought to be closely associated with the development of human cancers and hence numerous studies in this area have already been conducted in the United States and other Western countries. Comparatively few prospective studies have been published in Japan, especially for Hokkaido people. The present investigation was therefore performed to assess links between four leading cancers and some of the Japanese common dietary factors through a cohort study (1984-2002) in Hokkaido by analyzing 1,524 men and 1,634 women separately aged 40 and over. Adjusted Cox proportional hazard regression was used to calculate the relative risk (RR) for each dietary factor. For men, two dietary factors, miso soup (RR=0.2, 95% confidence interval (95%CI)=0.1-0.8) and pickled vegetables (RR=0.2, 95%CI=0.1-0.8) were associated with lower risk for stomach and colorectal cancer respectively. For women, three factors, namely salty confectionary (RR=3.5, 95%CI=1.1-10.9), black tea (RR=3.8, 95%CI=1.1-13.6), and carbonated drink/juice (RR=3.9, 95% CI=1.4-11.1) appeared related to an elevated risk of stomach cancer. However, further analysis simultaneously with all other adjusted factors indicated only carbonated drink/juice (RR=3.1, 95%CI=1.1-8.9) to present a significant risk factor for stomach cancer. One factor, namely wild edible plants (RR=3.3, 95%CI=1.1-9.8), increased the risk for colorectal cancer in women. None of the dietary components were significantly associated with lung or pancreatic cancers. This study also indicated a wide variation in the impact of dietary factors by sex and cancer site, in line with earlier work, pointing to a necessity for careful interpretation. Further epidemiological investigations by sex with more study subjects and confounding factors will be useful for determining the contribution of individual dietary factors to development of human cancers in Hokkaido, Japan.

[The association of systemic sclerosis with malignant neoplasms].

The rate of concomitance of systemic sclerosis and malignant neoplasm is not still ascertained. Therefore we reviewed 8,327 patients who were diagnosed with systemic sclerosis and received public financial aid from the Ministry of Health, Labour and Welfare of Japan in 1999. The concomitance rate was 3.1% of all patients, however, it was more frequent among men than among women (5.4% for men and 2.8% for women, respectively, P<0.01), and the mean age of patients with complicated malignant neoplasms was significantly higher than that of patients without malignancy (P<0.01). For comparison with the Japanese general population, O/E ratios (ratio of observed-to-expected malignant neoplasms) were calculated, and it was found that both men and women had significantly higher O/E ratios (O/E ratio 2.31, 95% confidence interval [CI] 1.68-2.94, P<0.001 for men and O/E ratio 1.64, 95% CI 1.41-1.86, P<0.001 for women). In addition we also assessed laboratory findings including autoantibodies and respiratory function tests for patients with malignant neoplasms by logistic regression analysis adjusted for sex and age. Decreased DLco (pulmonary CO diffusing capacity) appeared to be a risk factor for the concomitant malignant neoplasms among patients with systemic sclerosis (odds ratio 2.00 for DLco < or = 70%, CI 1.06-3.74, P=0.032). These results may help to elucidate the etiology of systemic sclerosis.

[Epidemiological study on patients with systemic sclerosis receiving financial aid for treatment].

We conducted an epidemiological study of systemic sclerosis in Japan using the records of patients who had been registered to receive public financial aid. A total of 10,956 patients were registered as having systemic sclerosis in 1999. We statistically analyzed the data on the patients, including sex, age, major symptoms, and laboratory findings. We also made contingency tables in order to evaluate the correlations of the data. Our study estimated that the male/female ratio was 1:7.3. The mean ages of male and female patients were 58.8 and 58.5 years old, respectively. The major symptoms were as follows: Raynaud's phenomenon 92.4%, skin sclerosis 94.7%, dyspnea 29.9%, and dysphagia 32.2%. With respect to specific antibodies, antinuclear antibody was present in 92.2%, antitopoisomerase I antibody in 27.5%, anticentromere antibody in 37.7%, and antiribonucleoprotein antibody in 19.9%. Making contingency tables, we could elucidate the association of antitopoisomerase I with lung fibrosis.

Traditional Japanese diet and prostate cancer.

The traditional Japanese diet has been suggested by some researchers to be associated with a decreased risk of prostate cancer (PCa). In this paper, we assumed the following three characteristics of the traditional Japanese diet high in soybean products, high in fish, and low in red meat. Isoflavones, polyunsaturated long chain (n - 3) fatty acids, and saturated fatty acids were thought to be micronutrients in biological etiology relevant to soybean products, fish, and red meat, respectively. Analytical epidemiological studies on the risk of PCa were identified using the MEDLINE database from 1998 to 2007. Some published studies showed a negative association of soybean products and isoflavones to PCa risk, an inverse association for fish or polyunsaturated long chain (n - 3) fatty acids such as eicosapentaenic acid (EPA) and docosahexaenoic acid (DHA) with PCa risk, and a positive association of red meat or saturated fatty acids with PCa risk, respectively. In conclusion, although it is possible that the traditional Japanese diet may reduce the risk of PCa through a combination of characteristics such as being high in soybean products, high in fish, and low in red meat, further well-designed epidemiological studies such as nested case-control studies with nutritional analyses of blood samples are needed to confirm this association.

Relationship of serum superoxide dismutase activity and lifestyle in healthy Japanese adults.

Superoxide dismutase (SOD) is an antioxidant enzyme that acts to degrade superoxide, a major causitive factor for oxidative stress associated with cancer, cardiovascular disease, and various other ailments. Here, to assess an association between antioxidants and lifestyle factors related to cancer risk, we analyzed serum SOD activity among the subjects within a large-scale cohort study in Japan. As results, significant differences in serum SOD activity were found between the sexes (lower in males), among female age groups (lower in younger individuals), and in males with the BMI (lower in those with a high BMI). Linear increase in serum SOD activity with aging and decrease with BMI were observed in females. Significantly low SOD activity was evident in male heavy smokers. In contrast, elevation was noted in female frequent drinkers. In conclusion, our findings do suggest associations between serum SOD activity and lifestyle factors. However, for further study, establishment of a standard measurement method for SOD activity should be a high priority.

Serum insulin-like growth factors I and II, insulin-like growth factor binding protein-3 and risk of breast cancer in the Japan Collaborative Cohort study.

The Japan Collaborative Cohort Study for Evaluation of Cancer Risk (JACC Study) was planned in the late 1980s as a large-scale cohort study of persons in various areas of Japan. In the present study, we conducted a nested case-control study and examined associations of breast cancer risk with serum levels of insulin-like growth factors I and II (IGF-I, IGF-II), as well as insulin-like growth factor binding protein-3 (IGFBP-3), among women who participated in the JACC Study and donated blood at the baseline. Sixty-three women who died or suffered from breast cancer were examined. Two or three controls were selected to match each case for age at recruitment and the study area. Controls were alive and not diagnosed as having breast cancer at the diagnosis date of the cases. Associations between the serum IGF-I, IGF-II, IGFBP-3 and breast cancer risk were evaluated using a conditional logistic regression model. In premenopausal Japanese women, IGF-I showed a marginal negative dose-dependent association with the breast cancer risk (trend P= 0.08), but any link disappeared on taking into account IGFBP-3 (trend P= 0.47), which was likely to be inversely associated with the risk. In postmenopausal women, IGFBP-3 showed a marginal dose-dependent association with the risk (trend P= 0.06). Further studies are needed to confirm these findings.

Prostate cancer risk in relation to insulin-like growth factor (IGF)-I and IGF-binding protein-3: A nested case-control study in large scale cohort study in Japan.

High levels of insulin-like growth factor (IGF)-I are reported to be associated with an increased risk of prostate cancer. On the other hand, the insulin-like growth factor binding protein-3 (IGFBP-3) may decrease the risk. We therefore investigated the influence of serum IGF-I and IGFBP-3 on prostate cancer risk in a case-control study nested within a large-scale cohort in Japan (the Japan Collaborative Cohort Study). Information on lifestyle and sera of the subjects were collected in 1988-90. Serum IGF-I, IGF-II and IGFBP-3 were measured in sera stored at -80 degrees C by immuno-radiometric assay. In 13,508 male subjects of the cohort who donated sera, 40 cases and 120 controls (1:3 matched with age and survey area) were identified. Ages of the cases ranged from 59 to 79 years, with a mean of 69.8. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated for the highest and middle tertiles compared with the lowest in controls using a conditional logistic model. Non-adjusted ORs for the highest tertiles were 0.99 (95% CI, 0.34-2.91) for IGF-I (trend-P = 0.60), 1.91 (95% CI, 0.68-5.38) for IGFBP-3 (trend-P = 0.23), 1.73 (95% CI, 0.69-3.47) for IGF-II (trend-P = 0.23), and 0.67 (95% CI, 0.26-1.76) for the IGF-I/IGBP-3 ratio (trend-P = 0.83). Serum levels of IGF-I, IGF-II, IGFBP-3, or IGF-I/IGFBP-3 ratio were thus not thought to be associated with risk of prostate cancer.

A prospective study of educational background and breast cancer among Japanese women.

OBJECTIVE: This prospective cohort study examined the association between educational level and breast cancer incidence in Japan. METHOD: A baseline survey was conducted between 1988 and 1990 among 110,792 residents of 45 areas, aged 40-79 years. Data were restricted to 24 areas where incidence registry data were available, and to subjects which provided information on educational level (32,646). The subjects were assigned to three groups according to their level of education (<16, 16-18, 18<). During 13 years of follow-up (328,931 person-year), 169 cases of breast cancer were newly diagnosed. RESULTS: Women with a high level of education had an increased risk of breast cancer (HR = 1.93, 95 percent confidence interval (95% CI): 1.18, 3.16, in women with the highest educational level) compared with women with the lowest educational level. Adjustment for lifestyle and reproductive factors did not substantially change the results. In addition, when analyses were stratified by age subgroups, the educational difference in breast cancer incidence was more evident among the younger than the elder subgroup. CONCLUSION: The present results suggested that cancer prevention strategies should recognize women with a higher educational level as a high risk group for breast cancer.

Marital status and having children and mortality in the Japan Collaborative Cohort Study for Evaluation of Cancer (JACC).

Marital status has been identified as an important social factor associated with mortality. Interesting results were obtained in the present analyses of the Japan Collaborative Cohort Study. Death of spouse was positively associated with risks of male death from all causes, all cancers, and ischemic heart diseases, compared with married status. Divorce or separation was positively associated with risks from all causes among men and women, all cancers among women, and single status was also positively associated with risks from all causes among men and women, and ischemic heart diseases among men. Having large numbers of children was also found to be a risk factor.