Association between decreasing trend in the mortality of adult T-cell leukemia/lymphoma and allogeneic hematopoietic stem cell transplants in Japan: analysis of Japanese vital statistics and Japan Society for Hematopoietic Cell Transplantation (JSHCT)

Adult T-cell leukemia/lymphoma (ATLL) is a peripheral T-cell neoplasm with a very poor outcome. However, several studies have shown a progress in the treatment. To evaluate the effect of the progress in the treatment of ATLL in a whole patient population, we used vital statistics data and estimated age-adjusted mortality and trends in the mortality from 1995 to 2009. Since allogeneic hematopoietic stem-cell transplantation (allo-HSCT) has been introduced as a modality with curative potential during study period, we also evaluated the association of the annual number of allo-HSCT and the trend of the mortality of ATLL. Endemic (Kyushu) and non-endemic areas (others) were evaluated separately. Significance in the trend of mortality was evaluated by joinpoint regression analysis. During the study period, a total of 14 932 patients died of ATLL in Japan, and mortality decreased significantly in both areas (annual percent change (95% confidence interval (CI)): Kyushu, -3.1% (-4.3, -1.9); others, -3.4% (-5.3, -1.5)). This decreasing trend in mortality seems to be associated with an increase in the number of allo-HSCTs (Kyushu, R-squared=0.70, P=0.003; and others, R-squared=0.55, P=0.058). This study reveals that the mortality of ATLL is now significantly decreasing in Japan and this decreasing trend might be associated with allo-HSCT.