Effect of Strongyloides stercoralis infection and eosinophilia on age at onset and prognosis of adult T-cell leukemia

Abstract

Onset of adult T-cell leukemia (ATL) usually follows a long period of vital latency. Strongyloides stercoralis infection has been considered a cofactor of leukemogenesis. Hypereosinophilia (HE) is also observed and could be associated with either the presence of parasites or the leukemic process. In non-Hodgkin's lymphoma, eosinophilia may or may not affect prognosis. To determine whether infection with S stercoralis and therefore eosinophilia has a significant effect on the development of ATL, we studied two variables in 38 patients: age at onset and median survival rate. Infected (Ss+) patients (n = 19) were younger (P=.0002) and survived longer (P=.0006) than uninfected (Ss-) patients (n = 19) (median age, 39 vs 70 years; median survival, 167 vs 30 days). Mean survival of patients with hypereosinophilia (HE+) was not significantly different from that of patients without hypereosinophilia (HE- ) (P=.57). However, overall survival was longer for Ss+HE+ patients than for Ss-HE- patients (P=.01; 180 vs 30 days) or Ss-HE+ patients (P=.03; 180 vs 45 days). Among patients with mean survival more than 180 days, Ss+HE+ patients survived longer (P= .028). Our data confirm that cofactors related to the environment, such as S stercoralis and hypereosinophilia associated with S stercoralis or human T-cell leukemia virus, type 1 (HTLV-1) might be important in HTLV-1-associated leukemogenesis and suggest that hypereosinophilia affects the prognosis of HTLV-1-associated leukemia.