The Japan Collaborative Cohort Study (JACC Study) for Evaluation of Cancer Risk sponsored by the Ministry of Education, Science, Sports and Culture of Japan (Monbusho): Report of Basic Concepts and Basic Results
BACKGROUND: A large-scale population-based cohort study would offer the best evidence of a relation between lifestyle and cancer. METHODS: The Japan Collaborative Cohort Study (JACC Study) for Evaluation of Cancer Risk sponsored by the Ministry of Education, Science, Sports and Culture of Japan (Monbusho) was established and carried out from 1988 to 1990 in 45 areas in Japan. Epidemiological information, such as demographic information, past medical history, exercise/sports activities engaged in, frequency of food intake, smoking and alcohol drinking status and so on, was collected by a self-administered questionnaire. Blood samples were collected from each participant at screening in 37 out of 45 areas to investigate risk factors of cancer relating to biochemical substances in blood. Collected sera were divided into 3-5 tubes (100-500μL per tube) and stored at -80°C. Additionally, about 5 years after the baseline survey, an interim survey regarding lifestyle changes was conducted in 31 areas. We followed the study subjects for mortality, move-outs, and cancer incidence, if possible (in 24 areas). RESULTS: There were 127,477 participants (54,032 men and 73,445 women) registered in the study. Of these, 110,792 subjects (46,465 men and 64,327 women), aged 40 to 79 years at baseline, were eligible for follow-up. Sera were stocked from 39,242 subjects, and interim survey was carried out on 46,650 subjects. CONCLUSIONS: The JACC Study provides useful evidence for cancer prevention in Japan. J Epidemiol 2005; 15: S4-S8.
BACKGROUND: A self-administered questionnaire on dietary habits used in the JACC Study contained a 40-item food frequency questionnaire (FFQ). Although more than 110 thousand subjects enrolled in JACC Study and responded to the FFQ, no validation study has been conducted to date. METHODS: Eighty-five volunteers among the cohort members completed 2 FFQs (FFQs 1&2) and 12-day weighed dietary records (WDR). The interval between the two FFQs was one year. During the one year, the subjects carried out a 3-consecutive-day WDR in each season. We tested the reproducibility by using two FFQs. Also, we tested the validity of the FFQ by using the 12-day WDR as a gold standard. RESULTS: The intake frequencies of the 2 FFQs often agreed, showing the Spearman correlation coefficients ranging from 0.42 (edible wild plants) to 0.86 (coffee). The Spearman correlation coefficients of the energy and nutrient intakes from FFQ2, and that of the 12-day WDR were 0.20(energy) to 0.46 (animal protein, potassium). After adjusting the energy intake, the correlation coefficients showed 0.21(fish fat) to 0.51(animal fat). When classifying the FFQ2 and WDR by quartiles and examining the degree of agreement between the two methods, we obtained its median 30%. CONCLUSIONS: The FFQ is suitable to deal with a large group of subjects. However, since the energy and the amount of nutrient intake from this FFQ can not show the overall dietary intake situation, the subjects' dietary intake should be assessed by categories. J Epidemiol 2005; 15: S9-S23.
BACKGROUND: The aim of this study was to determine the frequency of food intake and estimated nutrient intake in the JACC study cohort. METHODS: The subjects were 46,465 men and 64,327 women aged 40-79 years who responded to the self-administered food frequency questionnaire. We calculated the dietary intake of major nutrients by multiplying the frequency of consumption of each food with each portion size, estimated from a validation study. RESULTS: Women reported to more likely consume vegetables, seaweed, fruits, sweets, oolong-tea, western-style-breakfast, and less likely to consume rice and miso-soup than men. Women reported less preference of salty foods and fatty foods than men. Compared with men, women had higher mean intakes of carotene and vitamin C, and lower intake of total energy, carbohydrate and sodium. The frequency of consumption of beef, chicken, dairy products, fresh fish, fish products, rice, and miso-soup increased with age in men, and that of vegetables, seaweed, beans, tofu, fruits, sweets, and green-tea increased with age in both sexes. Men aged 40-49years had the lowest mean intake levels of crude fiber, calcium, iron, retinol, carotene, and vitamins A, C, and E. Women aged 40-49years had the lowest mean intake levels of crude fiber, iron, and vitamins C. Women aged 70-79years had the lowest mean intake levels of calcium, retinol, and vitamins A. CONCLUSIONS: Women had a more westernized dietary pattern than men. Elderly men had a mixture of unhealthy and healthy dietary patterns while elderly women generally had a healthier dietary pattern compared with younger persons. J Epidemiol 2005; 15: S24-S42.
BACKGROUND: Physical activity is thought to play an important role in the maintenance and promotion of health, and practical questionnaires assessing levels of physical activity are currently a widely used method in epidemiological research. METHODS: As a part of the Japan Collaborative Cohort Study (JACC Study) for Evaluation of Cancer Risk sponsored by the Ministry of Education, Science, Sports and Culture of Japan (Monbusho), we investigated the status of physical activity of cohort participants aged 40-79. A total of 110,792 participants (46,465 men and 64,327 women) completed the baseline survey from 1988-1990. Questionnaires concerning physical activity contained the following questions: 1) How much time per week on average do you spend engaging in sports or physical exercise? (at least 5 hours, 3-4 hours, 1-2 hours, little); 2) How much time per day on average do you spend walking either indoors or outdoors? (longer than 1 hour, 30 min-1 hour, about 30 min, little). RESULTS: In total, 68.7% of men and 76.2% of women responded with "little" to the amount of time spent engaged in sports or physical exercise. The proportion of time spent on habitual physical exercise (sports and physical exercise of one hour or more per week) was lowest in the 50-59 years age group and increased with age among participants aged 50-79. In addition, 49.4% of men and 50.7% of women responded with "more than 1 hour per day" to the amount of time spent walking. CONCLUSION: These results show that the proportion of habitual physical exercise was relatively low in the JACC Study and increased with age among participants aged 50-79, whereas almost half walked for more than one hour a day. J Epidemiol 2005; 15: S43-S47.
BACKGROUND: In a cohort study, information on an individual is taken at baseline, after which it usually remains fixed. There is some risk that this will lead to misclassification and cause weakened or biased results. To prevent such distortion, following up of exposure is important, although it is still scarce in practice. METHODS: In the Japan Collaborative Cohort Study for Evaluation of Cancer Risk (JACC Study) sponsored by Monbusho (Ministry of Education, Science, Sports and Culture of Japan), 37,838 (14,531 males and 23,307 females) subjects out of a cohort of 127,477 inhabitants answered an interim questionnaire on food intake frequency consisting of 33 items about five years after registration. The longterm reproducibility was assessed using Spearman's correlation coefficients and agreement. From data at two time points, longitudinal change, age effect, and secular trend were examined. Subjective changes in these items at the time of the interim survey were also compared to longitudinal changes. RESULTS: Spearman's correlation coefficients varied from 0.27 (fruit juice in males) to 0.55 (beef in females and milk in males), and agreement from 29.9% (fruit juice in males) to 61.4% (liver in females). Correlation was relatively stronger in meat and dairy products and weaker in vegetables and fruits. In both males and females, most increased food item was edible wild plants followed by confectioneries (males) and yogurt (females). CONCLUSION: Over five years, food intake was considerably changed. These interim data could be used for a long-term follow-up study to prevent the results becoming weakened or biased. J Epidemiol 2005; 15: S48-S55.
BACKGROUND: Observing longitudinal changes in smoking and drinking habits is important for evaluating the risk of incidence and death from cancer or other diseases in a cohort study. METHODS: Smoking and drinking habits at baseline and about five years later among 18,312 males and 28,338 females were obtained from the baseline and interim surveys in the Japan Collaborative Cohort Study for Evaluation of Cancer Risk (JACC Study) sponsored by Monbusho (Ministry of Education, Science, Sports and Culture of Japan). Changes in smoking and drinking habits between the two surveys were observed. Odds ratios for quitting these habits at interim survey were estimated. RESULTS: Percentages of current smokers at baseline and interim surveys were 51.0% and 45.5% in males, and 5.2% and 4.8% in females, respectively. Percentages of current drinkers at baseline and interim surveys were 78.0% and 73.2% in males, and 29.5% and 23.5% in females, respectively. The number of cigarettes per day among male current smokers and the usual amount of alcohol consumed on each occasion among current drinkers decreased between the two surveys. Odds ratios for smoking cessation increased with age at baseline and decreased with the number of cigarettes per day at baseline. Odds ratios for drinking cessation increased with age at baseline and decreased with the usual amount of alcohol consumed on each occasion at baseline. CONCLUSION: The decrease in smoking and drinking habits was observed during the five-year followup period. Higher age and lower levels of exposure were associated with quitting smoking or drinking. J Epidemiol 2005; 15: S56-S66.
BACKGROUND: Subjects of the Japan Collaborate Cohort Study (JACC Study) gave peripheral blood samples collected between 1988 and 1990. We conducted to investigate whether levels of serum components measured after 9 years of frozen storage are stable or not. METHODS: To assess the degradation of frozen serum components in the JACC Study, we compared levels of various components (IGF-I, IGF-II, IGFBP-3, TGF-β1, sFas, and total SOD activity) between fresh and stored sera collected from other inhabitants. Serum levels of constituents were measured by immunoradiometric assay (IGF-I, IGF-II and IGFBP-3), quantitative enzyme immunoassay (TGF-β1), enzyme-linked immuno-adsorbent assay (sFas), and an improved nitrite method (SOD activity). RESULTS: The coefficients of variation for intra- and inter-assay precisions of the measurements were less than 9%. Levels of IGF-I, IGF-II, IGFBP-3, TGF-β1 and sFas in sera after storage for 9 years at - 80°C were similar to those of fresh sera newly collected from inhabitants. The distributions of serum IGF-I, IGF-II, IGFBP-3, TGF-β1, sFas and SOD activity for specimens collected from different individuals tended to be similar to those of serum levels for frozen specimens collected from different individuals and stored for 9 years. CONCLUSIONS: There was no statistically significant difference in distribution of measured values of IGF-I, IGF-II, IGFBP-3, TGF-β1, and sFas between newly collected sera and frozen specimens stored for 9 years. Thus, measurements of these serum constituents of specimens stored for the JACC Study can be reliably used in nested case-control study. J Epidemiol 2005; 15: S67-S73.
BACKGROUND: We have been conducting a cohort study named "the Japan Collaborative Cohort Study (JACC Study) for Evaluation of Cancer Risk sponsored by the Ministry of Education, Science, Sports and Culture of Japan (Monbusho)" since 1988. The aim of this paper is to describe the mortality of our JACC cohort in the follow-up period from 1988 through 1999, to compare it with the mortality, especially cancer deaths, of the Japanese population in the same period and to compare the causes of mortality by district among the cohort. METHODS: We conducted a follow-up study of 110,792 Japanese inhabitants aged 40-79 years in 1988-1990 for about 10 years to the end of 1999. RESULTS: Of 46,465 males, 37,750 (81.2%) were alive, 7,238 (15.6%) were dead and 1,477 (3.2%) had moved out of the study areas. The figures were 57,016 (88.6%), 4,940 (7.7%) and 2,371 (3.7%) among 64,327 females, respectively. The mean follow-up period was 9.9 years. The proportion of cancer deaths by site in our cohort members was almost same as the Japanese population aged 40-79 years old in 1995. Sex-specific standardized mortality ratios of total deaths, all cancer deaths, and most cancers in our cohort were less than 100 in both males and females for total cohort and the cohort by district. CONCLUSION: Our cohort members appeared to be almost the same or slightly healthier and less likely to die from total causes and cancers than the general population. J Epidemiol 2005; 15: S74-S79.
BACKGROUND: As endpoint of cohort studies on cancer, the incidence, rather than the mortality is preferable. Of 45 areas in the Japan Collaborative Cohort Study (JACC Study), surveys for incidence of cancer were conducted in 24. METHODS: The proportion of the study subjects aged 40 to 79 years in areas of survey for the incidence of cancer (65,184 persons) was 58.2% of the total subjects of the JACC Study (110,792 persons). Among the 24 areas of survey for the incidence of cancer (ASI), 10 areas were combined because of similarity. Then, we present the incidence rate of cancer among 15 ASI unified from the 24 ASI by gender according to area. We also report the completeness of the survey for cancer incidence presenting the mortality-incidence ratio (MI ratio) among the ASI. RESULTS: Where a population-based cancer registry was utilized, the MI ratio deviated from 0.31 to 0.61 in the male subjects and from 0.15 to 0.53 in the female subjects. However, where a populationbased cancer registry was not used, the MI ratio deviated from 0.25 to 0.72 in the male subjects and from 0.13 to 0.79 in the female subjects, and there was an area where the MI ratio exceeded 0.70 in both of the male and female subjects. CONCLUSION: Establishment of population-based cancer registries is strongly desired throughout Japan to assess risk factors of cancer development for primary prevention of cancer. J Epidemiol 2005; 15: S80-S85.