EPIDEMIOLOGY AND BIOSTATISTICS DIVISION

22.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, environmental and genetic factors. Several epidemiological projects are currently in progress.
Foods and Nutrients in the Etiology of Human Cancer (Nutritional Epidemiology)

    The division has initiated a population-based prospective study on diet and cancer (JPHC Study) by conducting a baseline survey with questionnaire and collection of blood and health check-up data,^(238-²⁴¹⁾ in collaboration with the Cancer Information and Epidemiology Division and the National Cardiovascular Center, in which approximately 140,000 individuals from 11 public health center areas will be followed-up for 20 years. As of November 2001, 6,892 deaths, 6,184 cancers, 2,520 strokes and 447 myocardial infarctions had been documented. Several basic investigations have been conducted to validate the quality of the JPHC study. The sensitivity of self-reports of cancer was only 36%, which strongly suggests the necessity for a cancer registry in this cohort.⁽²⁴²⁾ Food frequency questionnaires used in the baseline and 5-year follow-up surveys were validated using 28 day dietary records and biomarkers such as serum level or urinary excretion with respect to nutrient (e.g. fatty acid, isoflavone) and dietary supplement intakes.^(127,^128,^243,²⁴⁴⁾ A specific carotene food composition table was developed to estimate intake of alpha- and beta- carotene, separately.⁽²⁴⁵⁾ Standardization of HbA1c reduced the difference in measured values between assay systems, which suggests its importance in combining data from different areas of the JPHC Study.⁽²⁴⁶⁾ The effect of smoking on the serum level of pepsinogens was analyzed by the status of Helicobacter pylori infection. ⁽²⁴⁷⁾
    Besides the JPHC study, a cross-sectional study for 400 Japanese women revealed that several nutrients correlate with bone mineral density and the associations differ depending on the menopausal status.⁽²⁴⁸⁾
Environmental and Genetic Interaction in the Etiology of Human Cancer (Molecular Epidemiology)

    Two case-control studies of gastric cancer in Japanese Brazilians and Brazilians not of Japanese ancestry in Sao Paulo were conducted to clarify the role of genetic susceptibility and environmental carcinogenesis. The ethnic difference in hOGG1exon 7 genetic polymorphism (repair enzyme of oxyradical DNA) was much greater than the case-control difference, which suggests that this polymorphism is unlikely to be associated with gastric cancer.⁽²⁴⁹⁾ Serum IgG antibody titer to H. pylori was lower in cases than in controls in both ethnic groups, however it was lower in Japanese than in non-Japanese in both cases and controls.⁽²⁵⁰⁾ Epstein-Barr virus associated gastric cancer was significantly higher in non-Japanese Brazilians than Japanese Brazilians.⁽²⁵¹⁾ The serum level of selenium was significantly lower in Japanese Brazilians than Japanese in Japan, which may be associated with the low selenium content in rice consumed in Sao Paulo.⁽²⁵²⁾
    Besides the study in Brazil, a cross-sectional study in coke oven workers in China observed that the variant genotype of the CYP1A1 exon7 and alcohol drinking resulted in the enhancement of polycyclic aromatic hydrocarbon metabolism indicated by urinary 1-hydroxypyrene excretions.⁽²⁵³⁾
An Epidemiological Evaluation of Cancer Prevention

    The available evidence suggests that the risk of gastric 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 gastric carcinogenesis has progressed to the seven year stage 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 completed its intervention program with reasonable compliance for 550 residents in a high risk area for gastric cancer.
Epidemiological and biostatistical support for basic and clinical researches

    Epidemiological and biostatistical support have been provided for the prognostic and clinical analysis of colorectal cancer,^(221,²⁵⁴⁾ breast cancer, ⁽²²²⁾ and pancreatic cancer,⁽²³⁵⁾ lung cancer,⁽²⁵⁵⁾ histopathological atherosclerotic lesions,⁽²⁵⁶⁾ and Werner's syndrome.⁽²⁵⁷⁾




22.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, environmental and genetic factors. Several epidemiological projects are currently in progress. Foods and Nutrients in the Etiology of Human Cancer (Nutritional Epidemiology) The division has initiated a population-based prospective study on diet and cancer (JPHC Study) by conducting a baseline survey with questionnaire and collection of blood and health check-up data,^(238-²⁴¹⁾ in collaboration with the Cancer Information and Epidemiology Division and the National Cardiovascular Center, in which approximately 140,000 individuals from 11 public health center areas will be followed-up for 20 years. As of November 2001, 6,892 deaths, 6,184 cancers, 2,520 strokes and 447 myocardial infarctions had been documented. Several basic investigations have been conducted to validate the quality of the JPHC study. The sensitivity of self-reports of cancer was only 36%, which strongly suggests the necessity for a cancer registry in this cohort.⁽²⁴²⁾ Food frequency questionnaires used in the baseline and 5-year follow-up surveys were validated using 28 day dietary records and biomarkers such as serum level or urinary excretion with respect to nutrient (e.g. fatty acid, isoflavone) and dietary supplement intakes.^(127,^128,^243,²⁴⁴⁾ A specific carotene food composition table was developed to estimate intake of alpha- and beta- carotene, separately.⁽²⁴⁵⁾ Standardization of HbA1c reduced the difference in measured values between assay systems, which suggests its importance in combining data from different areas of the JPHC Study.⁽²⁴⁶⁾ The effect of smoking on the serum level of pepsinogens was analyzed by the status of Helicobacter pylori infection. ⁽²⁴⁷⁾ Besides the JPHC study, a cross-sectional study for 400 Japanese women revealed that several nutrients correlate with bone mineral density and the associations differ depending on the menopausal status.⁽²⁴⁸⁾ Environmental and Genetic Interaction in the Etiology of Human Cancer (Molecular Epidemiology) Two case-control studies of gastric cancer in Japanese Brazilians and Brazilians not of Japanese ancestry in Sao Paulo were conducted to clarify the role of genetic susceptibility and environmental carcinogenesis. The ethnic difference in hOGG1exon 7 genetic polymorphism (repair enzyme of oxyradical DNA) was much greater than the case-control difference, which suggests that this polymorphism is unlikely to be associated with gastric cancer.⁽²⁴⁹⁾ Serum IgG antibody titer to H. pylori was lower in cases than in controls in both ethnic groups, however it was lower in Japanese than in non-Japanese in both cases and controls.⁽²⁵⁰⁾ Epstein-Barr virus associated gastric cancer was significantly higher in non-Japanese Brazilians than Japanese Brazilians.⁽²⁵¹⁾ The serum level of selenium was significantly lower in Japanese Brazilians than Japanese in Japan, which may be associated with the low selenium content in rice consumed in Sao Paulo.⁽²⁵²⁾ Besides the study in Brazil, a cross-sectional study in coke oven workers in China observed that the variant genotype of the CYP1A1 exon7 and alcohol drinking resulted in the enhancement of polycyclic aromatic hydrocarbon metabolism indicated by urinary 1-hydroxypyrene excretions.⁽²⁵³⁾ An Epidemiological Evaluation of Cancer Prevention The available evidence suggests that the risk of gastric 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 gastric carcinogenesis has progressed to the seven year stage 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 completed its intervention program with reasonable compliance for 550 residents in a high risk area for gastric cancer. Epidemiological and biostatistical support for basic and clinical researches Epidemiological and biostatistical support have been provided for the prognostic and clinical analysis of colorectal cancer,^(221,²⁵⁴⁾ breast cancer, ⁽²²²⁾ and pancreatic cancer,⁽²³⁵⁾ lung cancer,⁽²⁵⁵⁾ histopathological atherosclerotic lesions,⁽²⁵⁶⁾ and Werner's syndrome.⁽²⁵⁷⁾