SUMMARY REPORTS OF EXCHANGE SCIENTISTS

(1) Atsuhiko Sakamoto, M.D.
Tokyo University, Department of Pathology
Faculty of Medicine

Sponsors and Host Institutions:
Professor Juan Rosai
Department of Pathology
Yale University School of Medicine
Dates of Visit: October 4, - November 2, 1990

Summary of Activities:
During my stay in the United States, I visited six institutions including the host institution of Yale University, and discussed various problems in the pathology of thyroid tumors and uterine cervical cancer.
At Yale University, I discussed with Professor Rosai some differences in the histologic features of poorly differentiated carcinoma and insular carcinoma of the thyroid. The former was proposed by us in 1983. The latter was introduced by Professor Rosai and his staff in 1984. Both the types of thyroid cancer that occur in high-risk groups. Through discussion and slide review, we clarified that both categories were derived from the same basic cell source. We will start a cooperative study of thyroid cancer pathology, especially in high-risk groups, using Japanese and U.S. cases.
At the Massachusetts General Hospital, Professor Vickery and I discussed subtypes of follicular carcinoma, and the histology of invasive follicular tumors.
At the University of Chicago, I met with Professor Wied and observed how his group makes histologic diagnoses of early stage cancer of the uterine cervix. We discussed the Bethesda system: the newly proposed diagnostic system of gynecological cytology, which is intensively promoted by Professor Weid. Also talked about various problems of gynecologicai pathology at George Washington University with Professor Silverberg, at Massachusetts General Hospital with Professor Scully and at NIH with Dr. Solomon.
Throughout the visit, I obtained a lot of information and material from the U.S. specialists. I believe these will be quite useful for my future work.



(2) Ryuichiro Sasaki, M.D.
Department of Preventive Medicine
Nagoya University School of Medicine

Sponsors and Host Institutions:
Brian E. Henderson, M.D.
Director of the Norris Comprehensive Cancer Center
University of Southern California
Robert W. Miller, M.D.
Chief, Clinical Epidemiology Branch
National Cancer Institute
Walter C. Willet, M.D.
Professor of Epidemiology and Nutrition
Harvard School of Public Health
Dates of Visit: November 5 - 15, 1990

Summary of Activities:
We started a cohort study in 1988 which should provide us with ideas about preventing or decreasing deaths from cancer in Japan. We have had no big cohort study in cancer epidemiology except at Dr. Hirayama, which started in 1965. Therefore, we need new knowledge concerning such a study. The main objective of my visit to the U.S. was to study how to maintain a big cohort study and how to solve possible problems, as dealt with at three institutes and by discussions with those who have had long experience.
During my visit to USC, NCI and Harvard University, I met not only researchers but also many technical staff members who have been engaged in various cohort studies, and was able to see many special instruments for making them. Furthermore, I had a chance to visit a community in which a cohort study was in progress. Here I would like to summarize some points which I learned during my visit.
1. The different status of research environments: Generally epidemiologic research requires long periods, much manpower and considerable funds. In the U.S. they have well planned systems, well trained experts for every step of the study and well organized computer systems. As for a manpower, there are many well trained staff members, such as computer scientists, technical researchers, nurse practitioners and medical secretaries. As regards computer systems, there are many types, which save manpower and diminish mistakes. These great differences in the environment for a studies in the U.S. as compared with Japan was basically due to differences in the funds available.
2. The problem of informed consent: In Japan, we have few epidemiologic studies which were made after getting informed consent. So this was a major feature about which I intended to learn during my visit. In the U.S., first of all, researchers are required to get consent from a person before he or she enters a cohort study. After getting consent, the cohort is formed and the study begins.
Furthermore, it is necessary to contact cohort members, to obtain consent to cooperate in the next step giving the members new beneficial information from the study thus far.
The refusal rate in the first step may be 40-50% in some cohort studies, but the rate in the subsequent steps is not so high, less than 5%. Getting consent might make it easier to do a study with diminished attrition as it progresses. Therefore, I feel, in epidemiologic studies in Japan, we should make more effort to obtain consent to cooperate in studies.
3. The usefulness of studies added to a cohort study: The usefulness of some additional studies has been well known. Many additional studies will be conducted in Japan also, especially to assess the validity of the information in a cohort study. Many of these additional studies have been used for verifying and/or adding information to the study. In the U.S., as far as I saw, sometimes they have used some series of additional studies to estimate new facts from the original information. This kind of additional studies might make understanding easier or explain the outcomes of the cohort study. I was strongly impressed that we should do these types of additional studies in Japan.
4. The effort to keep the information valid: The validity of the study is essential in any type of study in the medical field. For this purpose, in the U.S., most researchers paid close attention to coding of the information as well as gathering the information. As for mortality data, they first assess the validity of the information referring to the medical records. In the next step, they use some special persons for the coding of the cause of death to avoid the differences between coders. We should make efforts to avoid these simple errors not only in cohort studies but also in all kinds of epidemiologic studies in Japan.

ADDITIONAL COMMENTS:
I have been pleased to have this opportunity to visit the U.S. and to know the details of recent progress of cancer epidemiology in the U.S. I hope that this program will continue for a long time. My only comment is that researchers hoping to visit the U.S. will be helped if they can get early information as to whether they can obtain this grant or not.