Approximately 140,000 people have participated in JPHC. Of those, approximately 60,000 people have provided blood samples for study purposes, and the blood samples have been stored frozen at the National Cancer Center. In implementing a study using stored blood samples, first, a study protocol is submitted to the Ethical Review Board of the National Cancer Center, and undergoes a rigorous review focused on ethical considerations, etc. in medical studies in human subjects. For more information about ethical reviews of research at the National Cancer Center, please visit their official website (in Japanese). The study projects that have been implemented upon approval of the Ethical Review Board are as follows. The overview of each study project can be viewed by clicking on the study theme. All studies are the studies in which results are kept anonymous, and the characteristics of test data for each group are compared. Although we do not handle each individual’s test results separately, if you feel that your sample is subject for a certain study listed below, but do not want it to be included into the study, please contact the JPHC Study Administration Office. Refusal to allow your blood sample to be used for the study will not result in any disadvantage for your visit for a medical examination, etc. Also, due to the nature of the study design of a “nested case-control study,” samples that have been provided may not necessarily be used for the corresponding study.

1. “Case-control study of gastric cancer within a cohort using blood samples from JPHC”

Among many factors involved in the incidence of gastric cancer, food factors that have been considered important in the past, and Helicobacter pylori infection that has gained attention in recent years, are major contributing factors. At the same time, the association between gastric cancer and food factors and Helicobacter pylori infection is not yet clearly understood, and there is a great need for investigation. However, there are only a few studies investigating the association between food factors and Helicobacter pylori infection and gastric cancer using blood sample data, and many of the studies remain within retrospective or cross-sectional studies at present. Thus, as part of JPHC study, we will make anonymous and use blood samples already collected and stored, and will investigate the association between subsequent incidence of gastric cancer and various parameters, through the method of nested case-control study. Hematology tests are planned to include: 1) Helicobacter pylori, inflammation-related: Helicobacter pylori, CagA, PGI, PGII, 2) antioxidants: vitamin E, carotenoid, polyphenols, 3) other: IGFs, etc.

2. “Case-control study of breast cancer within a cohort using blood samples from JPHC”

Early menarche, delayed menopause, late childbearing, nulliparity, high height, obesity, etc. are well known, as risk factors of breast cancer, to affect hormone levels of the body such as estrogen. However, there are few prospective studies that directly measure blood estrogen levels, and there is only one study that was conducted in Japanese. On the other hand, a high intake of fruits and vegetables is suggested to be an inhibiting factor in breast cancer, but it is not known which nutrient is involved. Also, no conclusion has been reached for the inhibitory action of phytoestrogen which is contained substantially in soybean products, against breast cancer. The current situation is that almost no prospective studies have been conducted to investigate the association of food factors and breast cancer on blood levels, not on food intake levels. There have been no reports of epidemiological studies in Japan investigating the association between exposure to so-called endocrine disruptors which are a concern that they may affect endocrine systems by binding with estrogen receptors, and breast cancer incidence. Thus, as part of JPHC study, we will make anonymous and use blood samples already collected and stored, and will investigate the association between subsequent incidence of breast cancer and various parameters, through the method of nested case-control study. Hematology tests are planned to include: 1) endogenous hormone-related: estradiol, sex hormone-binding globulin, etc. 2) exogenous parahormone-related: isoflavonoid, bisphenol A, phetalic acid esters, etc. 3) antioxidants: polyphenols, carotenoid, vitamin C, etc.

3. “Case-control study of colorectal cancer within a cohort using blood samples from JPHC”

There are many factors suggested to be associated with incidence of colorectal cancer, of which food factors are considered to be one of the major contributing factors. There are numerous studies on the association between nutrient intake levels estimated from questionnaires and colorectal cancer in epidemiologic studies, but there are only a limited number of studies investigating the association between blood nutrient levels and disease incidence. In addition, inflammation is suggested to play a significant role, since decrease in risk is consistently confirmed in people taking aspirin or NSAIDs. However, the association between inflammatory markers and colorectal cancer is still at a stage of experimentation or clinical studies on progression or prognosis. Thus, as part of JPHC study, we will make anonymous and use the data that have been followed up since 1990 (cohort I) and 1993 (Cohort II), questionnaire data on lifestyle habits, and blood samples collected/stored at start of the study, and will investigate the association between subsequent incidence of colorectal cancer and various parameters, through the method of nested case-control study. Hematology tests are planned to include: 1) nutrient-related: folic acid-related, fatty acid-related, antioxidant, etc., 2) inflammation-related: High-sensitivity CRP, etc.

4. “Case-control study of stroke/myocardial infarction within a cohort using blood samples from JPHC”

It is suggested, in experimental and pathologic studies, that infections and antioxidants are involved in the progression of arteriosclerosis, but it has not been made clear how these factors are involved in the development of cardiovascular diseases (stroke, myocardial infarction) in Japanese. Also, the interaction of infections and antioxidants in regard to the development of cardiovascular disease has not been investigated in Japan and abroad. Thus, as part of JPHC study, we will make anonymous and use the data that have been followed up since 1990 (cohort I) and 1993 (Cohort II), questionnaire data on lifestyle habits, and blood samples collected/stored at start of the study, and will investigate the association between subsequent incidence of stroke/myocardial infarction and various parameters, through the method of nested case-control study. Hematology tests are planned to include: 1) hs-CRP, homocysteine, 2) antibody to Clamydia pneumonia/Helicobacter pylori infection, 3) serum vitamin E, polyphenol, etc., 4) serum lipids such as LDL-cholesterol

5. “Epidemiological study on major viral/bacterial infections based on multipurpose cohort and lifestyle factors associated with subsequent incidence of cancer”

Hepatitis C virus (HCV), Hepatitis B virus (HBV), adult T cell leukemia virus (HTLV-I), Helicobacter pylori (H. pylori), etc. are known to be the most important cancer-related viruses and bacteria in Japan. These virus/bacteria infected persons are known to have a higher risk of developing liver cancer, adult T-cell leukemia, cervical cancer, and gastric cancer. These virus/bacteria-related cancers account for more than 30% of all cancer occurrences. Recently strategy for prevention of these viral/bacterial infections is moving forward, but questions as to what type of lifestyle habits enhances or inhibits subsequent incidence of cancer after becoming infected with these virus/bacteria remain unsolved. In addition, to carry out this study, separate analysis becomes necessary based on presence/absence of viral/bacterial infections, but such investigation cannot be implemented with the existing information from this study, only, since data on presence/absence of viral/bacterial infections can be obtained. Therefore, using the measurements of the blood samples already collected/stored and information on viral/bacterial infections in the study participants provided by the collaborating medical centers, we will obtain actual prevalence rates of infection with major cancer-related virus/bacteria in Japan including HCV, HBV, HTLV- I, H. pylori, etc. in JPHC study sites, and will investigate the association between each viral/bacterial infection and food/lifestyle habits, and enhancing/inhibiting factors such as food/lifestyle habits, etc. in developing a cancer in persons infected with virus/bacteria, and will contribute to the prevention of these virus/bacteria-related cancers.

6. “Case-control study of prostate cancer within a cohort using blood samples from JPHC”

It is suggested that endocrine factors are involved in incidence of prostate cancer, since prostate tissue develops into androgen dependence. Also, association between growth factor concentration, such as insulin-like growth factors-I (IGF-I), etc. which is involved in cell division, and prostate cancer has been noted. However, there are no prospective studies that directly measure in-blood levels in Japanese. On the other hand, preventive effect of phytoestrogens, such as isoflavone which shows a high intake among Japanese, and especially, that of equol, have been reported as an inhibiting factor in prostate cancer. The intake level of equol, however, cannot be estimated from the questionnaire, and investigation based on in-blood levels becomes necessary. Further, nutrients such as β-carotene, vitamin D, vitamin E have been reported as preventive factors, but there have been almost no prospective studies in Japan investigating the association between food factors and prostate cancer based on in-blood levels. There have been no reports of epidemiological studies in Japan investigating the association between the exposure to so-called endocrine disruptors, which are a concern as they may affect endocrine systems by binding with estrogen receptors, and prostate cancer incidence. Thus, as part of JPHC study, we will make anonymous and use blood samples already collected and stored, and will investigate the association between subsequent incidence of prostate cancer and various parameters, using the method of nested case-control study. Through this study, we expect to gain scientific evidence that can be applied to the prevention of prostate cancer in Japan. Hematology tests are planned to include: 1) endogenous hormone-related: testosterone, sex hormone-binding globulin, IGF-I, etc. 2) exogenous parahormone-related: isoflavonoid, organochlorine compound, etc. 3) nutrient-related: β-carotene, vitamin D, vitamin E, etc.

7. “Case-control study of stroke/myocardial infarction within a cohort using blood samples from JPHC”

Among many factors involved in the incidence of stroke/myocardial infarction, food factors that have been considered important in the past, and inflammatory markers of high-sensitivity C-reactive protein (hs-CRP) that have gained attention in recent years, and Helicobacter pylori (H. pylori) and Clamydia pneumoniae (C. preumoniae) infections are major contributing factors. At the same time, association between food factors and inflammation/infections and stroke/myocardial infarction and their interactions are not yet clearly understood, and there is a great need for investigation. However, there are only a few studies investigating the association between food factors and inflammation/infections and stroke/myocardial infarction using blood sample data, and many of the studies remain within retrospective or cross-sectional studies at present. Thus, as part of JPHC study, we will make anonymous and use blood samples already collected and stored, and will investigate the association between subsequent incidence of stroke/myocardial infarction and various parameters, through the method of nested case-control study. Hematology tests are planned to include: 1) inflammation/infection-related: hs-CRP, homocysteine, H. pylori antibody, C. pneumoniae antibody, etc. 2) antioxidants: vitamin E, polyphenol 3) other: serum lipids such as LDL-cholesterol, etc.