Late Relapses in Acute Myelogenous Leukemia: Analysis of Characteristics and Outcome.

The majority of patients with acute myelogenous leukemia (AML) who achieve complete remission (CR) with initial chemotherapy will eventually relapse. Most relapses occur in the first three years and rare patients relapse after being in CR for more than 5 years. We have reviewed retrospectively 2347 patients with AML treated at M D Anderson Cancer Center from January 1980 to July 2008. Of the total cohort, 1366 patients achieved CR and among these 942 patients relapsed. We identified 11 patients (1.16%) who relapsed after being in CR >5 years; these patients are the focus of this analysis. There were 4 females and 7 males. Their median age was 66 years (range 37–79), and their median presentation white blood cell (WBC) count was 2.3 x10⁹/L (range, 1.1–92.3). The FAB classification was M2 in 5 patients, M1, M4, M5, M6 in 1 patient each, and unknown in 2 patients. Initial cytogenetics were diploid in 6, del(7q) in one, miscellaneous in 1, and unavailable in 3 patients. Initial therapy was with combination of idarubicin (Ida) and cytarabine (Ara-C) in 4 patients (1 with additional fludarabine), amsacrine based in 3, daunorubicin (Dauno) single agent in 2 and other agents in 2 patients. All patients except one achieved CR after the first induction course; one patient needed 2 cycles of induction to achieve CR. None underwent an allogeneic stem cell transplant in first CR. The median duration of CR was 81 months (range, 60–137).

At the time of relapse, median WBC count was 4.4 x10⁹/L (range 1.7–48.8). Karyotype at relapse was diploid in 2, del(5)del(7) in 1, del(6)del(7) in 1, trisomy 8 in 1, hyperdiploid in 2, add(2q) and add(6q) in 1 each and unavailable in 2 patients. The karyotype at relapse was different from the initial finding in 8 of 8 patients with available data at both time points. Treatment for relapse included Ida (or Dauno) with Ara-C in 8 patients (1 with additional fludarabine), and other agents in 3 patients. The response to treatment was CR in 4, partial remission in 2, resistant in 4 and unknown in 1. No patient underwent an allogeneic stem cell transplant in second CR. The median duration of the second CR was 2 months (range 0–37). The median survival after relapse was 6.4 months (range 1–39). Median survival from initial diagnosis of AML was 107 months (range 68–143). We conclude that late relapses in AML (>5 years after CR) are infrequent (1.16% of all relapses) and response to their subsequent therapy is poor; best responses occur with a regimen similar to the initial induction regimen. The karyotype at relapse is frequently different raising the question of a second AML versus relapse with the original clone.