Challenges in breast and cervical cancer control in Japan.

Since the mid-1990s, there has been an increasing incidence of, and mortality from, cervical and breast cancers in Japan. Such an increase has raised concerns over the efficiency of Japan's screening programmes for these cancers. Although citizens benefit from universal health coverage, the Japanese health insurance system mostly focuses on tertiary prevention and disease treatment, while secondary prevention (screening) is low priority. Citizens have multiple opportunities to be screened for cancer-either through programmes organised by municipalities, or individual or collective, opportunistic and comprehensive health check-ups on a voluntary basis. Despite this, however, participation is as low as 35% of the target population for both cancers. In this Policy Review, we discuss the challenges in the prevention of breast and cervical cancers in Japan, particularly focusing on the structure of the National Health Insurance system and the National Cancer Control Plan, reasons for low participation as a result of social and political attitudes, as well as providing recommendations to overcome these challenges. Japanese women would benefit from new measures to increase participation, a national data surveillance programme to monitor screening activities, and the implementation of a quality assurance system among all providers.

Increase of colon and rectal cancer incidence rates in Japan: trends in incidence rates in Miyagi Prefecture, 1959-1997.

BACKGROUND: During recent decades, colorectal cancer incidence rates have been rapidly increasing in Japan. To investigate trends in colorectal cancer incidence rates, we analyzed incidence data during 39 years between 1959 and 1997 in Miyagi Prefecture, Japan. METHODS: Using age-period-cohort models, we evaluated the effects of time period and cohort on colon and rectal cancer incidence. Model fitting was based on eleven 5-year age groups (30-34 to 80-84), eight 5-year time periods, and 18 overlapping birth cohorts of 10 years each. RESULTS: The analysis found a significant (p=0.04) and upward period effect on female colon cancer incidence, and a significant (p<0.01) and upward cohort effect on male colon cancer incidence. An upward period effect was also observed for male colon cancer incidence without significance. For rectal cancer incidence, a significant cohort effect was found among both males and females. CONCLUSIONS: In light of known risk factors of colorectal cancer, the effects of period and cohort might be related to the change in the prevalence of risk factors such as high intake of meat and animal fat, and obesity. The improved diagnostic procedures including the spread of cancer screening might be responsible for the period effect. Although the significant cohort effects may give a caution for a continuous increase of colorectal cancer incidence, the future trend may be influenced by the period-related factors. Successive monitoring of cancer incidence and prevalence of risk factors is required.

Science and ethics in epidemiology.

This article is the summary of my Special Lecture at the 14th Annual Scientific Meeting of the Japan Epidemiological Association in 2004. Epidemiology is defined as the "science of investigating the distribution of diseases in human populations and their determinants." Recent advances in study methodology, especially a widespread conduct of randomized controlled trials (RCTs), have strengthened the scientific basis of epidemiology. When a highly scientific method of investigation is applied to humans, the ethical aspects of the study also become an issue. However, it would also be unethical to use new drugs and vaccines without scientific evidence. The ethical aspects and the scientific aspects of epidemiologic research are thus both very important, but conflict with each other, often causing dilemmas. I would discuss how we could solve these dilemmas and thus contribute ourselves to health promotion and disease prevention of human populations. Finally, I would propose the new paradigm of changing epidemiology into a "neotype science" and transformation of EKIGAKU (epidemiology) into EKIGAKU (beneficial science).

Reliability and validity of the Multidimensional Health Locus of Control Scale in Japan: relationship with demographic factors and health-related behavior.

We assessed the reliability and validity of the Multidimensional Health Locus of Control Scale (MHLC scale) in a rural Japanese community. The study subjects were 2388 men and 2454 women aged 40-79 years, who completed a questionnaire regarding socio-demographics, health-related behavior, such as smoking and drinking, and the MHLC. The Cronbach alpha of the MHLC scale, which is an indicator of the internal consistency of the scale, was within the range 0.62-0.76. Elderly subjects, women, and subjects with fewer years of education showed more "external" belief, which is generally consistent with previous reports from overseas. Subjects with adverse health behavior, such as smoking and excess drinking, also had more "external" belief. These results indicate that the MHLC scale has sufficient reliability and validity among the Japanese population. Use of the MHLC scale should help to provide a better understanding of health belief among Japanese, and development of health education programs to prevent lifestyle-related disease.

Follow-up and mortality profiles in the Miyagi Cohort Study.

BACKGROUND: Findings from a large-scale population-based prospective cohort would lead us to better understanding of the relationship between lifestyle and health, thus better provision of strategies for disease prevention and health promotion. METHODS: We conducted a baseline survey with two self-administered questionnaires regarding lifestyle and personality on the residents aged 40 to 64 years in 14 municipalities of Miyagi Prefecture, Japan, during June through August, 1990. Out of the eligible 51,925 residents, 47,605 (91.7%) responded to the lifestyle questionnaire and formed the cohort under study. We then have been following up the subjects for mortality, migration, and incidence of cancer. RESULTS: During the follow-up from June 1990 through March 2001, 2,536 subjects (5.3%) died and 2,166 subjects (4.5%) emigrated. The distribution of the causes of death among the study subjects was quite consistent with the national average. CONCLUSIONS: In this cohort study, both the participation rate and the follow-up rate are satisfactorily high. We expect this Miyagi Cohort Study to provide the society with evidence for health promotion and disease prevention.

Cancer incidence profiles in the Miyagi Cohort Study.

BACKGROUND: There were few prospective cohort studies in Japan using cancer incidence as an endpoint. METHODS: We conducted a baseline survey with two self-administered questionnaires regarding lifestyle and personality on the residents aged 40 to 64 years in 14 municipalities of Miyagi Prefecture, Japan, during June through August, 1990. Out of the eligible 51,921 residents, 47,605 (91.7%) responded to the lifestyle questionnaire and formed the cohort under study. We collated the list of subjects in the cohort with the Miyagi Prefectural Cancer Registry data through December 31, 1997. To identify the same person between two data, we used four personal characteristics (sex, name, birthday, and municipality of dwelling). RESULTS: We ascertained 1,718 cases of incident cancer. In men, gastric cancer was the leading site of cancer (27.7%), followed by lung cancer and colon cancer. In women, breast cancer was the most common (19.6%), followed by gastric cancer and colon cancer. CONCLUSIONS: By record linkage with regional cancer registry data, it becomes possible for us to investigate the effect of various life-styles on cancer incidence in the Miyagi Cohort Study. We expect this data to contribute to the progress of research on cancer etiology and cancer prevention.

Cigarette smoking and mortality in Japan: the Miyagi Cohort Study.

BACKGROUND: We examined the association between smoking and all-cause mortality among Japanese men and women. METHODS: In 1990, 18,945 men and 17,107 women in Miyagi Prefecture in rural northern Japan (40-64 year of age) completed a self-administered questionnaire including items on smoking. Cox regression was used to estimate relative risk (RR) of mortality according to smoking categories, with adjustment for age, education, marital status, past history of diseases, drinking, body mass index, walking, and dietary variables. During 11 years of follow-up, 1,209 men and 499 women had died. RESULTS: Multivariate RRs of all-cause mortality for current smokers as compared with never smokers were 1.71 (95% confidence interval, 1.44-2.03) for men and 1.44 (95% confidence interval, 1.06-1.94) for women. Among men, risk in past smokers who had quit smoking for 15 years or longer was not different from the risk in never smokers (RR, 0.97; 95% confidence interval, 0.68-1.39). Of all deaths, 34% in men and 4% in women were attributable to current or past smoking. CONCLUSIONS: This study indicates that smoking increases the risk of premature death among middle-aged Japanese men and women and that substantial proportion of death, especially for men, is attributable to smoking.

Walking and mortality in Japan: the Miyagi Cohort Study.

BACKGROUND: Although many studies in western populations demonstrated that time spent walking was associated with a reduced risk of all-cause mortality, data on Japanese has been sparse. METHODS: In 1990, 20,004 men and 21,159 women in Miyagi Prefecture in rural northern Japan (40-64 year of age) completed a self-administered questionnaire including a question on time spent walking. Cox regression was used to estimate relative risk (RR) of mortality according to three levels of walking (30 minutes or less, between 30 minutes and one hour, and one hour or more), with adjustment for age, education, marital status, past history of diseases, smoking, drinking, body mass index, and dietary variables. During 11 years of follow-up, 1,879 subjects had died. RESULTS: Time spent walking was inversely associated with risk of all-cause mortality: compared with men and women who walked one hour or more per day, multivariate RR (95% confidence intervals) was 1.06 (0.95-1.19) for subjects who walked between 30 minutes and one hour per day, and 1.16 (1.04-1.29) for subjects who walked 30 minutes or less per day (P for trend=0.007). Shorter duration of walking was associated with increased mortality among men who were never smokers (P for trend=0.081) and past smokers (P for trend=0.026), but not among currently smoking men (P for trend=0.751). We observed similar effect modification for women. CONCLUSIONS: Time spent walking was associated with a reduced risk for all-cause mortality, especially among nonsmoking men and women.

Body mass index and mortality in Japan: the Miyagi Cohort Study.

BACKGROUND: The relation between body mass index (BMI) and mortality is not well established. The objective of this study was to examine the association in Japanese adults. METHODS: In 1990, 18,740 men and 20,870 women in Miyagi Prefecture in rural northern Japan (40-64 years of age) completed a self-administered questionnaire including height and weight. Cox regression was used to estimate relative risk (RR) of mortality according to levels of BMI, with adjustment for age, marital status, smoking, drinking, walking, and weight change since 20 years of age. RESULTS: During 11 years of follow-up, 1,121 men and 567 women had died. Compared with the referent BMI category (23.0-24.9), women in the highest BMI category (BMI>30.0) had a RR of death of 1.64 (95% confidence interval (CI), 1.09-2.49) and men and women in the lowest BMI categories (BM1<18.5) had a RR of death of 2.06 (95% CI, 1.49-2.84) and 1.83 (95% CI, 1.17-2.88), respectively, after adjustment for potential confounders and after exclusion of deaths occurring in the first three years of follow-up. We did not observe significant differences in mortality for subjects with wide range of BMI (18.5 or higher in men and 18.5 to 29.9 in women). CONCLUSIONS: The risk of death from all causes increases in lean men and women, and obese women in this cohort.

Alcohol consumption and mortality in Japan: the Miyagi Cohort Study.

BACKGROUND: We examined the association between alcohol consumption and all-cause mortality in Japanese men and women. METHODS: From June through August 1990, a total of 39,076 subjects (20,660 men and 18,416 women) in 14 municipalities of Miyagi Prefecture in rural northern Japan (40-64 years of age) completed a self-administered questionnaire that included information about alcohol consumption and various health habits. During 11 years of follow-up, we identified 1,879 deaths (1,335 men and 544 women). We used Cox proportional-hazards regression to estimate relative risk (RR) of all-cause mortality according to categories of alcohol consumption and to adjust for age, education, marital status, past histories of chronic diseases, body mass index, smoking, walking and dietary variables. RESULTS: Among men, the risk for all-cause mortality was significantly higher in past drinkers than never-drinkers (multivariate RR, 1.86; 95% confidence interval [CI], 1.50-2.29). There was a dose-response association between alcohol consumption and the risk of all-cause mortality among current drinking men: multivariate RRs in reference to never-drinkers (95% CI) were 1.10 (0.90-1.33), 1.17 (0.96-1.42), 1.16 (0.96-1.40), and 1.62 (1.32-1.99) in current drinkers who consumed less than 22.8 g, 22.8-45.5 g, 45.6-68.3 g, and 68.4 g or more alcohol per day, respectively (P for trend<0.001). Similar association was observed among women (P for trend=0.005). CONCLUSIONS: The results indicated that alcohol consumption tended to be associated with linear increase in risk of all-cause mortality among Japanese men and women, and the association was remarkable for younger men.

Health practices and mortality in Japan: combined effects of smoking, drinking, walking and body mass index in the Miyagi Cohort Study.

BACKGROUND: Evidence is limited regarding the association between the combinations of multiple health practices and mortality. METHODS: In 1990, 28,333 men and women in Miyagi Prefecture in rural northern Japan (40-64 year of age) completed a self-administered questionnaire. A lifestyle score was calculated by adding the number of high-risk practices (smoking, consuming > or = 22.8 g alcohol/d, walking < 1 hr/d, body mass index < 18.5 or > or = 30.0). Cox regression was used to estimate relative risk (RR) of mortality according to the lifestyle score, with adjustment for age, education, marital status, past history of diseases, and dietary variables. During 11 years of follow-up, 1,200 subjects had died. RESULTS: We observed linear increase in risk of death associated with increasing number of high-risk practices: compared with men who had no high-risk practices, multivariate RRs for men who had 1 to 4 practices were 1.20, 1.66, 1.94, and 3.96, respectively (P for trend<0.001), and corresponding RRs for women were 1.31, 2.14, 3.98, 5.56, respectively (P for trend<0.001). A unit increase in the number of high-risk practices corresponded to being 2.8 and 4.8 years older for men and women, respectively. CONCLUSIONS: In this prospective cohort study of middle-aged men and women in rural Japan, a larger number of high-risk practices was associated with linear increase in risk of all-cause mortality.

The increase of female breast cancer incidence in Japan: emergence of birth cohort effect.

During recent decades, breast cancer incidence has been increasing in Japan. According to the latest reports from several cancer registries in Japan, the breast has become the leading cancer site in female cancer incidence. To analyze the trend of breast cancer incidence in detail, we summarized female breast cancer incidence in Miyagi Prefecture, Japan during 1959-1997, and evaluated the period and cohort effect on breast cancer incidence using the age-period-cohort model. Age-specific and age-standardized rates have increased over successive calendar periods. Around 1980, an accelerated increase in these incidence rates took place. A full model including age, period and cohort was best fitted to the trend of incidence. In the model, the effects of period and cohort were statistically significant. The nonlinear effect for cohort indicates an increasing trend, beginning with the cohort in 1888-1897, and the nonlinear effect for period showed a clear increase in risk with calendar period. Furthermore, the full model including a linear component showed a steadily upward trend in the cohort effect. Based on our own epidemiologic studies previously conducted in Miyagi Prefecture, and other published reports, the cohort effect is likely to be related to the change in prevalence of women with risk factors such as low parity and insufficient breastfeeding. We believe that the emergence of the cohort effect is an important finding, although the period effect may also persist. The significant cohort effect may give a caution for continuous increase of breast cancer incidence in Japan.

Impact of walking upon medical care expenditure in Japan: the Ohsaki Cohort Study.

BACKGROUND: Physical activity is expected to reduce medical costs by lowering the risk for a variety of chronic diseases. However, little is known about the actual magnitude of medical cost saved by physical activity. We attempted to quantify the association between time spent walking and medical care costs, based on a 4-year prospective observation of National Health Insurance (NHI) beneficiaries in rural Japan. METHODS: In 27 431 Japanese men and women, aged 40-79 years, who had no functional limitation or conditions interfering with physical activity at the baseline survey in 1994, we ascertained all hospitalizations, outpatient visits, and the costs through computerized linkage with NHI claims history files between January 1995 and December 1998. RESULTS: Medical costs significantly reduced with longer time spent walking. Per capita medical cost was pound 111.80 per month (95% CI: 109.3, 114.2) in those who walked for < or =30 minutes/day, pound 108.10 (95% CI: 105.7, 110.5) in those who walked for 30 minutes-1 hour, and pound 97.30 (95% CI: 95.5, 99.0) in those who walked for > or =1 hour, after multivariate adjustment of potential confounders. CONCLUSIONS: This prospective study in Japan indicated that time spent walking was significantly associated with lower medical costs.

Personality and the risk of cancer.

BACKGROUND: The role of personality in the causation of cancer has been controversial. We examined this question in a large, prospective study. METHODS: From June through August 1990, 30 277 residents of Miyagi Prefecture in northern Japan completed a Japanese version of the short form of the Eysenck Personality Questionnaire-Revised and a questionnaire on various health habits. There were 671 prevalent cases of cancer at baseline, and 986 incident cases of cancer were identified during 7 years of follow-up, through December 1997. We used Cox proportional hazards regression to estimate the relative risk (RR) of incident cancer (total, stomach, colorectal, breast, and lung) according to four levels of each of four personality subscales (extraversion, neuroticism, psychoticism, and lie), with adjustment for sex, age, education, smoking, alcohol use, body mass index, and family history of cancer. Statistical tests were two-sided. RESULTS: Multivariable RRs of total cancer for individuals in the highest level of each personality subscale as compared with those in the lowest were 0.9 for extraversion (95% confidence interval [CI] = 0.7 to 1.1; P(trend) =.32), 1.1 for psychoticism (95% CI = 0.9 to 1.3; P(trend) =.96), 0.9 for lie (95% CI = 0.7 to 1.0; P(trend) =.19), and 1.2 for neuroticism (95% CI = 1.0 to 1.4; P(trend) =.06). There were no associations between any personality subscale and risk of specific cancers. Neuroticism showed statistically significant positive, linear associations with prevalent cancer at baseline (P(trend)<.001) and with the 320 incident cancer cases diagnosed within the first 3 years of follow-up (P(trend) =.03); however, it showed no association with the 666 cases diagnosed during the fourth through the seventh years of follow-up (P(trend) =.43). CONCLUSION: Our data do not support the hypothesis that personality is a risk factor for cancer incidence. The association between neuroticism and prevalent cancer may be a consequence, rather than a cause, of cancer diagnosis or symptoms.

Diet and systemic lupus erythematosus: a 4 year prospective study of Japanese patients.

OBJECTIVE: To investigate the associations of dietary factors with the occurrences of active disease and vascular damage in female patients with systemic lupus erythematosus (SLE). METHODS: Clinical and questionnaire data were collected from 279 female patients with SLE in a 1995 baseline survey. Dietary nutrients were estimated by a semiquantitative food frequency questionnaire and disease activity was evaluated based on the Lupus Activity Criteria Count. Patients were followed over 4 years (1995-99) and changes in disease activity and occurrences of major organ damage were determined. Using data from 216 patients with inactive disease whose dietary data were complete at baseline, the association of each nutrient intake with occurrence of active disease was evaluated. The relation of diet with the development of 3 types of vascular injury (ischemic heart disease, cerebrovascular accident, thrombotic events) was examined in 196 patients who had been inactive with no history of these injuries. Patients who developed these vascular events were put in one category and nutrient intakes at baseline were compared between patients who did or did not develop vascular events. RESULTS: A total of 9966 person-months were accumulated from the 216 inactive patients, among whom 43 patients developed active disease. The proportional hazard model including indicator variables for tertiles of each nutrient, total energy, and confounding variables revealed an inverse association of intake of vitamin C (p for trend = 0.005) and crude fiber (p for trend = 0.06) with the risk of active disease. The inverse association with vitamin C intake was also significant after Bonferroni adjustment. Patients who developed vascular events (n = 7) consumed a greater amount of vegetable fat at baseline than patients who did not (p = 0.04). CONCLUSION: Our findings suggest that dietary nutrients may modify clinical course of disease in female patients with SLE. Vitamin C intake is inversely associated with the risk of active disease, suggesting that vitamin C intake may prevent the occurrence of active SLE disease.

Validation of a food-frequency questionnaire for cohort studies in rural Japan.

OBJECTIVES: To examine the validity and reproducibility of a self-administered food-frequency questionnaire (FFQ) used for two cohort studies in Japan. DESIGN: Cross-sectional study. SETTING: Two rural towns in the Miyagi Prefecture, in north-eastern Japan. SUBJECTS: Fifty-five men and 58 women. RESULTS: A 40-item FFQ was administered twice, 1 year apart. In the mean time, four 3-day diet records (DRs) were collected in four seasons within the year. We calculated daily consumption of total energy and 15 nutrients, 40 food items and nine food groups from the FFQs and the DRs. We computed Spearman correlation coefficients between the FFQs and the DRs. With adjustment for age, total energy and deattenuation for measurement error with the DRs, the correlation coefficients for nutrient intakes ranged from 0.25 to 0.58 in men and from 0.30 to 0.69 in women, with median of 0.43 and 0.43, respectively. Median (range) of the correlation coefficients was 0.35 (-0.30 to 0.72) in men and 0.34 (-0.06 to 0.75) in women for food items and 0.60 (-0.10 to 0.76) and 0.51 (0.28-0.70) for food groups, respectively. Median (range) of the correlation coefficients for the two FFQs administered 1 year apart was 0.49 (0.31-0.71) in men and 0.50 (0.40-0.64) in women for nutrients, 0.43 (0.14-0.76) and 0.45 (0.06-0.74) respectively for food items, and 0.50 (0.30-0.70) and 0.57 (0.39-0.66) respectively for food groups. Relatively higher agreement percentages for intakes of nutrients and food groups with high validity were obtained together with lower complete disagreement percentages. CONCLUSIONS: The FFQ has a high reproducibility and a reasonably good validity, and is useful in assessing the usual intakes of nutrients, foods and food groups among a rural Japanese population.

Prognostic significance of the nocturnal decline in blood pressure in individuals with and without high 24-h blood pressure: the Ohasama study.

OBJECTIVE: To examine the relationship between the normal nocturnal decline in blood pressure and the risk of cardiovascular mortality in individuals with and without high 24-h blood pressure values. METHODS: We obtained 24-h ambulatory blood pressure readings from 1542 residents of Ohasama, Japan, who were aged 40 years or more and were representative of the Japanese general population. We then followed up their survival for a mean of 9.2 years. The relationship was analysed using a Cox proportional hazards model adjusted for possible confounding factors. RESULTS: There was a linear relationship between the nocturnal decline in blood pressure and cardiovascular mortality. On average, each 5% decrease in the decline in nocturnal systolic/diastolic blood pressure was associated with an approximately 20% greater risk of cardiovascular mortality. There were no significant interactions for the risk between 24-h systolic/diastolic blood pressure values and continuous values for the nocturnal decline in blood pressure ( for interaction 0.6). Even when 24-h blood pressure values were within the normal range ( 135/80 mmHg, average 118/69 mmHg), diminished nocturnal decreases in systolic/diastolic blood pressure were associated with an increased risk of cardiovascular mortality. CONCLUSIONS: This is the first study to demonstrate that a diminished nocturnal decline in blood pressure is a risk factor for cardiovascular mortality, independent of the overall blood pressure load during a 24-h period, in the general population.