Flowchart of patients included in the analysis. The clinical information of 395 patients with chronic- and smoldering-type ATL were collected (282 from hematologists and 113 from dermatologists). Among these patients, 128 were excluded for the following reasons: 95 for loss of data, 27 for unsatisfied diagnostic criteria of ATL, 4 for double registration resulting from hospital transfer, and 2 for being diagnosed before 2000. First, the remaining patients without those undergoing allo-HSCT were randomly divided into 2 groups: training samples-A and validation samples-A. The patients, including those undergoing allo-HSCT, were subsequently divided into 2 groups: training samples-B and validation samples-B.