EPIDEMIOLOGY AND BIOSTATISTICS DIVISION

18.EPIDEMIOLOGY AND BIOSTATISTICS DIVISION

　The Epidemiology and Biostatistics Division has planned and conducted independent and collaborative studies on cancer etiology and prevention, with a special focus on dietary factors. Several epidemiological projects are currently in progress, including cross- sectional, case- control, cohort and intervention studies. In addition, collaborative studies in the field of clinical and basic sciences are being conducted by providing statistical design, analysis and data processing support.
Foods and Nutrients in the Etiology of Human Cancer

　Diet has been implicated in the etiology of cancer occurrence and in the unique patterns of cancer incidence in Japan. However, epidemiological evidence regarding this issue has been limited. The division has therefore initiated a population- based prospective study on diet and cancer (JPHC Study), in collaboration with the Cancer Information and Epidemiology Division and the National Cardiovascular Center, in which approximately 140,000 individuals will be followed- up for 10 years or more. Among 55,000 population cohort members from 4 areas with a 9 year follow- up, 2,177 deaths and 2,167 incident cancers had been documented as of December 31,1998. Analysis of the association between alcohol consumption and all- cause and cancer mortality using seven- year follow- up data showed a J- shaped association.⁽²⁵⁰⁾ The validity of semi- quantitative food frequency questionnaire for estimating intake of several nutrients and positive predictive values for self- reported diseases such as cancer, cardiovascular diseases, diabetes and cataract have been examined.
　Several analyses were conducted in a cross- sectional study of randomly selected residents in five JPHC study areas. Plasma levels of antioxidant vitamins and carotenoids were inversely associated with the regional difference in gastric cancer mortality.⁽²⁵¹⁾ Serum n- 3 fatty acid level and fish intake was inversely associated with prostate cancer.⁽²⁵²⁾ A substituted fatty acid food composition table was developed for use in nutritional epidemiological studies of the Japanese population and open to public access on the division's internet home page.⁽²⁵³⁾ An international ecological study showed that fish consumption was associated with a reduced risk of all- cause, ischemic heart disease, and stroke mortality.⁽²⁵⁴⁾
Environmental and Genetic Interaction in the Etiology of Human Cancer

　The ethnic differences in cancer occurrence suggest an interaction between environmental and genetic factors. The division has been conducting several epidemiological studies in Brazil, a multi- ethnic nation with 1.2 million people of Japanese ancestry. Regardless of geographic difference in stomach cancer mortality and atrophic gastritis prevalence among genetic Japanese populations in Japan, Brazil and Peru, Helicobactor pylori infection was equally penetrated.⁽²⁵⁵⁾ The hOGG1 Ser326Cys polymorphism was associated with susceptibility to tobacco- related lung cancer in a case- control study in Okinawa.⁽¹⁰¹⁾
An Epidemiological Evaluation of Cancer Prevention Methods

　Practical prevention strategies are generally based on total evidence obtained from observational epidemiological studies, experimental animal studies and mechanistic interpretation. An evaluation based on intervention studies is, however, essential before recommending a strategy to the general public. The available evidence suggests that the risk of stomach cancer is increased in individuals with chronic atrophic gastritis and is decreased in those with a high consumption of fruit and vegetables and a low consumption of salted foods. A randomized controlled trial to assess the effectiveness of vitamin C supplementation on stomach carcinogenesis has progressed to the fifth year for individuals with chronic atrophic gastritis. Another randomized controlled trial to assess the effectiveness of dietary modification (less salt and more vitamin C and carotene)has progressed to the second year for 550 residents in a high risk area for gastric cancer. The Diet History Questionnaire used in this trial was also used to evaluate hypercholesterolemic workers. ⁽²⁵⁶⁾
Epidemiological and Biostastical Support for Basic and Clinical Researches

　Epidemiological and biostastical supports have been provided for the prognostic and clinical analysis of simple ovarian cyst,⁽²⁵⁷⁾ cancer of ovary,⁽²⁵⁸⁾ lung,^(247,²⁵⁹⁾ breast^(229,^230,²³⁸⁾ and large intestine.⁽²²⁸⁾




18.EPIDEMIOLOGY AND BIOSTATISTICS DIVISION



	The Epidemiology and Biostatistics Division has planned and conducted independent and collaborative studies on cancer etiology and prevention, with a special focus on dietary factors. Several epidemiological projects are currently in progress, including cross- sectional, case- control, cohort and intervention studies. In addition, collaborative studies in the field of clinical and basic sciences are being conducted by providing statistical design, analysis and data processing support. Foods and Nutrients in the Etiology of Human Cancer 　Diet has been implicated in the etiology of cancer occurrence and in the unique patterns of cancer incidence in Japan. However, epidemiological evidence regarding this issue has been limited. The division has therefore initiated a population- based prospective study on diet and cancer (JPHC Study), in collaboration with the Cancer Information and Epidemiology Division and the National Cardiovascular Center, in which approximately 140,000 individuals will be followed- up for 10 years or more. Among 55,000 population cohort members from 4 areas with a 9 year follow- up, 2,177 deaths and 2,167 incident cancers had been documented as of December 31,1998. Analysis of the association between alcohol consumption and all- cause and cancer mortality using seven- year follow- up data showed a J- shaped association.⁽²⁵⁰⁾ The validity of semi- quantitative food frequency questionnaire for estimating intake of several nutrients and positive predictive values for self- reported diseases such as cancer, cardiovascular diseases, diabetes and cataract have been examined. 　Several analyses were conducted in a cross- sectional study of randomly selected residents in five JPHC study areas. Plasma levels of antioxidant vitamins and carotenoids were inversely associated with the regional difference in gastric cancer mortality.⁽²⁵¹⁾ Serum n- 3 fatty acid level and fish intake was inversely associated with prostate cancer.⁽²⁵²⁾ A substituted fatty acid food composition table was developed for use in nutritional epidemiological studies of the Japanese population and open to public access on the division's internet home page.⁽²⁵³⁾ An international ecological study showed that fish consumption was associated with a reduced risk of all- cause, ischemic heart disease, and stroke mortality.⁽²⁵⁴⁾ Environmental and Genetic Interaction in the Etiology of Human Cancer 　The ethnic differences in cancer occurrence suggest an interaction between environmental and genetic factors. The division has been conducting several epidemiological studies in Brazil, a multi- ethnic nation with 1.2 million people of Japanese ancestry. Regardless of geographic difference in stomach cancer mortality and atrophic gastritis prevalence among genetic Japanese populations in Japan, Brazil and Peru, Helicobactor pylori infection was equally penetrated.⁽²⁵⁵⁾ The hOGG1 Ser326Cys polymorphism was associated with susceptibility to tobacco- related lung cancer in a case- control study in Okinawa.⁽¹⁰¹⁾ An Epidemiological Evaluation of Cancer Prevention Methods 　Practical prevention strategies are generally based on total evidence obtained from observational epidemiological studies, experimental animal studies and mechanistic interpretation. An evaluation based on intervention studies is, however, essential before recommending a strategy to the general public. The available evidence suggests that the risk of stomach cancer is increased in individuals with chronic atrophic gastritis and is decreased in those with a high consumption of fruit and vegetables and a low consumption of salted foods. A randomized controlled trial to assess the effectiveness of vitamin C supplementation on stomach carcinogenesis has progressed to the fifth year for individuals with chronic atrophic gastritis. Another randomized controlled trial to assess the effectiveness of dietary modification (less salt and more vitamin C and carotene)has progressed to the second year for 550 residents in a high risk area for gastric cancer. The Diet History Questionnaire used in this trial was also used to evaluate hypercholesterolemic workers. ⁽²⁵⁶⁾ Epidemiological and Biostastical Support for Basic and Clinical Researches 　Epidemiological and biostastical supports have been provided for the prognostic and clinical analysis of simple ovarian cyst,⁽²⁵⁷⁾ cancer of ovary,⁽²⁵⁸⁾ lung,^(247,²⁵⁹⁾ breast^(229,^230,²³⁸⁾ and large intestine.⁽²²⁸⁾