Evaluation of adult T-cell leukemia/lymphoma incidence and its impact on non-Hodgkin lymphoma incidence in southwestern Japan

The incidence of adult T-cell leukemia/lymphoma (ATL) and its impact on tha t of total non-Hodgkin lymphoma (NHL) were evaluated in Nagasaki, an area i n southwestern Japan where human T-cell lymphotropic virus type I (HTLV-I) is endemic. The first study area comprised 4 towns located on the K Islands , which had a population of 26,870 in 1990. The overall HTLV-I seroprevalen ce estimated from the serologic survey of 18,485 subjects was 16.2%. By usi ng the data from the Nagasaki Prefectural Cancer Registry (NPCR) and review ing clinical and laboratory information, we identified 40 cases of ATL and 35 cases of other NHL diagnosed between 1985 and 1995. The crude annual inc idence of ATL among 100,000 HTLV-I carriers aged 30 or older was estimated at 137.7 for men and 57.4 for women, with a significant sex difference afte r adjustment for age (rate ratio = 2.50, 95% confidence interval 1.32-4.73) . The cumulative risk from 30 to 79 years of age was estimated at approxima tely 6.6% for men and 2.1% for women. Among the entire population, ATL acco unted for 51 to 59% of the total NHL incidence, showing the strong impact o f HTLV-I infection. The second study area comprised the whole of Nagasaki P refecture (total population in 1990 = 1.56 million). Between 1985 and 1995, 989 cases of ATL and 1,745 cases of other NHL were registered in the NPCR. The world age-standardized annual incidence rate of ATL per 100,000 person s aged 30 or older was estimated at 10.5 for men and 6.0 for women, which a ccounted for approximately 37 to 41% of the total NHL incidence. (C) 2000 W iley-Liss, Inc.