Geographic Distribution of the Incidence of Adult T-cell Leukemia/Lymphoma and Other Malignancies in Nagasaki Prefecture, Japan

lymphoma. Methods: The authors investigated the geographic distribution of the incidence of adult T-cell leukemia/lymphoma and other malignancies in Nagasaki Prefecture, Japan, where HTLV-I is endemic. The world age-standardized incidence rates of adult T-cell leukemia/lymphoma and five cancers of other sites were calculated in 15 areas, using the data from the Nagasaki Prefectural Cancer Registry (1985–97). Results: The incidence of adult T-cell leukemia/lymphoma was found to be positively correlated with that of biliary tract cancer in men (person-years-weighted r = 0.49, P = 0.06) and liver cancer in women (r = 0.56, P = 0.03), but not with cancer of the stomach, lung or cervix uteri. Conclusions: The results may not support the hypothesis that HTLV-I infection is strongly associated with an increased risk of cancer of the stomach, lung or cervix uteri. The association between HTLV-I infection and cancer of the biliary tract and the possible interaction between hepatitis C virus and HTLV-I in the development of liver cancer should be evaluated by prospective cohort studies.