SUMMARY REPORTS OF EXCHANGE SCIENTISTS

(1) Hiroyuki Shimizu
Gifu University School of Medicine

SPONSORS AND HOST INSTITUTIONS:
Hosts:
Ross Prentice
Fred Hutchinson Cancer Research Center
Walter C. Willet
Harvard School of Public Health
William J. Blot
National Cancer Institute
Pelayo Correa
Louisiana State University Medical Center
Brian E. Henderson
University of Southern California School of Medicine
Laurence N. Kolonel
University of Hawaii at Manoa
Date of Visits: November 1 - November 30, 1992

SUMMARY OF ACTIVITIES:
Main objectives of my visit to the US under this program were collecting information on changing pattern of cancer among Japanese Americans and discussing practical problems in conducting epidemiological studies of migration and cancer. I visited six institutions described above and had the opportunity to exchange ideas with about 40 scientists including epidemiologists, biostatisticians, dietitians and molecular biologists. I also gave two seminars (Title: Age at Migration and Cancer among Japanese Americans) at the Fred Hutchinson Cancer Research Center and Harvard School of Public Health.
The discussions with the scientists gave me some suggestions or convictions, both of which will be useful to expand the study on migration and cancer particularly among Japanese immigrants to the US. The ideas and impressions obtained from the discussions are as follows:
1) Many epidemiological studies focusing on cancer etiology have been conducted and we know that some of the environmental factors are more important in developing cancer than host factors. However, we cannot yet indicate which factors or substance plays a critical role in developing cancer and when it initiates or promotes the cancer. We also little know how strong the effect of environmental factors are modified by host factors which are being elucidated by using new methods of molecular biology. I had a strong convictions that migrant population is still very important and useful to study the etiology of cancer of human because migrant population has similar host factors as the population in their homeland does and exposes to different environmental factors. Another useful point for the study is that they have different ages at beginning of exposure to environmental factors.
2) Epidemiologists realize that they cannot get enough information on the etiology of cancer only from classical methods of epidemiology like reviewing medical records or interviewing patients and controls. Molecular biologists feel that they have to collect samples not only from a few patients with cancer but also from many cases and their controls as epidemiologists usually collect information for the analysis. The cooperative study between molecular biologists and epidemiologists will make a new era in the study of caner etiology. In fact, we have often heard the term of "molecular epidemiology"
3) To use the methods of molecular biology in the field of epidemiological study they must be developed to be simple and less expensive. We must also keep in mind that findings from molecular biology are not necessarily sensitive compared with those from classical epidemiologic studies to explain the frequency of the disease in a population.
4) One of the most important steps for conducting further epidemiologic studies of cancers among Japanese Americans is collecting information on their life styles including detailed dietary habits as well as those information among whites in the US and Japanese in Japan based on the same or similar method.
5) It may be suggested that we should make focus on the cancers of some sites which show higher incidence rates in Japanese in Japan are much lower than those in whites.