Increased incidence of acute nonlymphocytic leukemia following therapy in patients with small cell carcinoma of the lung.

A group of 158 patients with small cell carcinoma of the lung were followed for 174.5 person-years of observation to determine the risk of acute leukemia. Three cases of acute nonlymphocytic leukemia were observed at 2.3, 2.7, and 3.0 years. The relative risk of developing leukemia was 316 (95% confidence limit, 76-818) and the actuarial risk was 25% +/- 13% at 3.1 years. The relative risk for leukemia was significantly increased in these patients (p less than 0.0001).