18. Epidemiology and Biostatistics Division
Formed in October 1994, the Epidemiology and Biostatistics Division has
planned and conducted independent and collaborative studies on cancer
etiology and prevention, with special focus on dietary factors. In this
respect, several types of epidemiological projects are currently in
progress, such as descriptive, ecological, case-control and cohort studies.
The Japan Clinical Oncology Group (JCOG) Statistical Center was moved to
this Division. In addition, collaborative studies in the field of clinical
and basic sciences are conducted through providing statistical design,
analysis and data processing support.
Ecological Study for Clues to Geographic Differences in Stomach Cancer
in Japan (Ecocancer Study)
To determine the cause of the 3-fold variation in stomach cancer mortality
in five areas in Japan, 1,004 randomly selected residents (631 men and 373
women) were intensively surveyed through questionnaires and biological
specimen collection. The serum level of selenium was not a predictor of
geographic differences in stomach cancer.(131) The risk factors of
Helicobactor pylori infection were investigated with this data set
and salty food intake was suggested.(129)
Population-based Prospective Study (Multi-purpose Koseisho Cohort I)
The five areas of the above ecological study were expanded to a total of a
60,000-population cohort study in 1990, and 50,000 questionnaires and
24,000 blood samples were collected to give baseline information. To obtain
more precise information on dietary habits, a semi-quantitative food
frequency questionnaire was developed in 1994 and will be used for the
second survey in February 1995. The dietary record survey to test the
validity of the questionnaire has been completed for a subsample of 200
cohort members.
Epidemiological Studies in Brazil (São Paulo Project)
Since 1987, epidemiological studies have been conducted on Japanese
immigrants and their descendants in Brazil. After determining the mortality
and cancer incidence among Japanese Brazilians, a cross-sectional survey of
randomly selected Japanese Brazilians was conducted to collect data on
prevaling lifestyle characteristics and certain biological markers. Serum
levels of macro- and micronutrients, body mass index, and blood pressure
were significantly different from those of Japanese in Japan.(130,131) A
case-control study of lung cancer showed that the use of black tobacco was
associated with an increase in risk(127) and that Msp I type
polymorphism of cytochrome P-450 IA1 was not related to
susceptibility.(126)
Randomized Controlled Field Trial with Antioxidant Micronutrients to
Prevent Stomach Cancer in High Risk Japanese Populations (HIRAKA
Project)
A chemoprevention trial is planned to test the efficacy of nutrient
supplementation for preventing stomach cancer among subjects with gastric
atrophy living in an area with a high stomach cancer mortality and low
serum beta-carotene level. A pilot study is being conducted among the
recipients of health check-ups and the feasibility of a randomized
controlled field trial will be tested.
Other Epidemiological Studies
An international collaborative study in 17 populations showed that the
adduct O6-methylguanine in peripheral blood leukocyte DNA was present in
16% of individuals among populations with a high stomach cancer rate, while
it was 1% among low risk populations.(137) A multi-center case-control
study revealed a quantitative association between alcohol consumption and
risk of esophageal cancer.(135)
JCOG Statistical Center
The center is responsible for (1) assisting with design of study protocols,
(2) registering and randomizing patients in each protocol, (3) managing and
editing all study data, (4) generating annual reports of protocol study
findings, and (5) researching statistical aspects of clinical trials. The
center's activities are closely coordinated with those of the JCOG, the
largest clinical cooperative cancer research group in Japan. The center
cooperated in 40 trials including 15 phase III trials and registered 2,117
patients in 1993-94, while generating the system of the statistical
center.
Collaborative Studies through Statistical Support
Prognostic factors were statistically analyzed for cancers of the uterine
cervix(7) and ovary.(138) Observer disagreement in histological
classification of ovarian tumors was revealed among three certified
pathologists and indicated the necessity of a review system in
multi-institutional clinical studies.(139)
List of papers
from this division
Table of Contents