Effect of therapy-related acute myeloid leukemia on the outcome of patients with acute myeloid leukemia

Therapy-related acute myeloid leukemia (t-AML) is a rare and almost always fatal late side effect of antineoplastic treatment involving chemotherapy, radiotherapy or the two combined. The present retrospective study intended to characterize t-AML patients that were diagnosed and treated in a single referral to an oncological institution in North Portugal. Over the past 10 years, 231 cases of AML were diagnosed and treated at the Portuguese Institute of Oncology of Porto, of which 38 t-AML cases were identified. Data regarding the patient demographics, primary diagnosis and treatment, age at onset of therapy-related myeloid neoplasm, latency time of the neoplasm, cytogenetic characteristics, AML therapy and outcome were collected from medical records. A previous diagnosis with solid tumors was present in 28 patients, and 10 patients possessed a history of hematological conditions, all a lymphoproliferative disorder. Breast cancer was the most frequent solid tumor identified (39.5% of all solid tumors diagnosed). The mean latency time was 3 years. In the present study, t-AML patients were older (P<0.001) and more frequently carried cytogenetic abnormalities (P=0.009) compared with <i>de novo</i> AML patients. The overall survival time was observed to be significantly poorer among individuals with t-AML (P<0.001). However, in younger patients (age, <50 years) there was no difference between the overall survival time of patients with t-AML and those with <i>de novo</i> AML (P=0.983). Additionally, patients with promyelocytic leukemia possess a good prognosis, even when AML occurs as a secondary event (P=0.98). To the best of our knowledge, the present study is the first to evaluate t-AML in Portugal and the results are consistent with the data published previously in other populations. The present study concludes that although t-AML demonstrates a poor prognosis, this is not observed among younger patients or promyelocytic leukemia patients.