Results of risk‐adapted therapy in acute myeloid leukaemia. A long‐term population‐based follow‐up study

In 1997–2003, a protocol for treatment of acute myeloid leukaemia (AML) (except promyelocytic leukaemia) was activated in four Swedish health care regions covering 50% of the national population. Based on cytogenetics and clinical findings, patients aged 18–60 yr were assigned to one of three risk groups. In this report we account for the long‐term clinical outcome of enrolled patients. Patients received idarubicin and cytarabine in standard doses as induction therapy and consolidation courses included high‐dose cytarabine. Allogeneic stem cell transplantation (allo‐SCT) from an human leucocyte antigen‐identical sibling was recommended in standard and poor‐risk patients, whereas unrelated donor transplant was reserved for poor‐risk patients. Autologous (auto‐SCT) was optional for standard or poor risk patients not eligible for allo‐SCT. Two hundred seventy‐nine patients with de novo or secondary (9%) AML, median age 51 (18–60) yr, corresponding to 77% of all patients in the population, were included. Twenty (7%) patients were assigned to the good risk group, whereas 150 (54%) and 109 patients (39%) were assigned to standard‐ and poor‐risk groups, respectively. Induction failures accounted for 55 patients; 16 early deaths eight of whom had white blood cell (WBC) >100 at diagnosis, and 39 refractory disease. Thus, complete remission (CR) rate was 80%. At study closure, the median follow‐up time of living patients was 90 months. Median survival time from diagnosis in the whole group was 27 months and 4‐yr overall survival (OS) rate was 44%. In good, standard, and poor risk groups, 4‐yr OS rates were 60, 57 and 24%, respectively. Median relapse‐free survival (RFS) time in CR1 was 25 months and RFS at 4 yr was 44%. Four‐year RFS rates were significantly (P < 0.001) different between the three risk groups; 64% in good risk, 51% in standard risk and 27% in poor risk patients. One hundred‐ten transplantations were performed in CR1; 74 allo‐SCT (50 sibling, 24 unrelated donor), and 36 auto‐SCT. Non‐relapse mortality was 16% for allo‐SCT patients. Outcome after relapse was poor with median time to death 163 d and 4‐yr survival rate 17%. Three conclusions were: (i) these data reflect treatment results in a minimally selected population‐based cohort of adult AML patients <60 yr old; (ii) a risk‐adapted therapy aiming at early allogeneic SCT in patients with a high risk of relapse is hampered by induction deaths, refractory disease, and early relapses; and (iii) high WBC count at diagnosis is confirmed as a strong risk factor for early death but not for relapse.