Interferon alfa as primary treatment of chronic myeloid leukemia: long-term followup of 71 patients observed in a single center

The purpose of this study was to evaluate the long-term outcome of interfer on (IFN) alfa treatment in patients with Philadelphia chromosome-positive c hronic myeloid leukemia (CML). Between 1984 and 1990, a total of 71 patient s with newly diagnosed CML had been enrolled into two consecutive IFN trial s at our institution. Follow-up extended to December 1998, resulting in a m edian observation period for surviving patients of 11.4 years. The median s urvival time from diagnosis was 5.9 years. A plateau in the actuarial survi val curve was found from 8.2 to 12.3 years following diagnosis with a proje cted 10-year survival rate of 32%. 'Landmark' studies showed a significant survival advantage for patients with karyotype responses. Of 68 patients ac cessible to calculation of the Hasford score, three were in the high risk g roup, 24 belonged to the medium risk group, and 41 had low risk features, T he majority of cytogenetic responders including all eight assessable patien ts in complete cytogenetic remission were in the low risk group. Achieving a cytogenetic remission was found to provide a survival advantage also for patients with low risk disease. Of the seven patients surviving more than 1 1 years, six were in continuous complete cytogenetic remission. Their favor able outcome appears to translate into an out-flattening of the survival cu rve for the 71 single center patients presented. It will be of interest to see whether prolonged follow-ups of the large multicentric randomized trial s will similarly show a subset of long-term surviving patients with ongoing IFN-induced remission.