Risk of leukemia associated with the first course of cancer treatment: an analysis of the Surveillance, Epidemiology, and End Results Program experience.

The risk of leukemia associated with the first course of cancer treatment was evaluated in over 440,000 patients diagnosed during 1973-80 (average follow-up = 1.91 yr) from the National Cancer Institute's Surveillance, Epidemiology, and End Results Program. Although the reporting of the first course of therapy probably was incomplete, 34 acute nonlymphocytic leukemias (ANLL) developed compared with 7.6 expected among 70,674 patients known to receive initial chemotherapy [relative risk (RR) = 4.5, 95% confidence interval (Cl) = 3.1-6.3]. Significant ANLL excesses were observed following chemotherapy for breast cancer (RR = 8.1), ovarian cancer (RR = 22.2), and multiple myeloma (RR = 9.5). Patients initially treated with radiation (with no record of chemotherapy) also had a significantly increased ANLL risk; 45 leukemias occurred versus 17.9 expected (RR = 2.5, 95% Cl = 1.8-3.4). In this group, excess ANLL were found following irradiation for uterine corpus cancer (RR = 4.0). Kidney and renal pelvis cancer patients had a twofold leukemia risk (all types) that was unrelated to treatment (RR = 2.2).