Estimation of rate of incidence of ATL among ATLV (HTLV-I) carriers in Kyushu, Japan.

From the mortality statistics on malignant lymphomas in Japan and nationwide studies on T- and B-cell malignancies, the number of deaths from adult T-cell leukemia/lymphoma (ATL) in adults older than 20 years in the Kyushu district was estimated at 339 or more per year in 1978-82. The incidence for ATL per 100,000 was estimated at 3.5 for adults and 5.7 for persons over 40 years of age in the Kyushu district. From the information from a nationwide study on the distribution of ATL virus (ATLV) carriers among volunteer blood donors, the number of ATLV-carriers in adults older than 20 years in Kyushu was calculated at 561,000 (310,000-793,000 at 95% confidence limit) in recent years. The incidence of ATL per 1,000 ATLV carriers in Kyushu was calculated at 0.60 (0.43-1.09) for adults, and 0.75 (0.55-1.18) for those over 40 years of age which was very close to the independently calculated figure of 0.84 (0.75-0.95) in the Goto Islands (the most typical ATL-endemic area). From these results, it was suggested that one case of ATL developed per year among 1,700 (900-2,300) ATLV-carrier adults and among 1,300 (800-1,800) ATLV carriers older than 40 years in Kyushu in recent years.