Increased risk of secondary acute nonlymphocytic leukemia after extended-field radiation therapy combined with MOPP chemotherapy for Hodgkin's disease

Abstract

The purpose of this study was to evaluate the influence of the number of mechlorethamine, vincristine, procarbazine, and prednisolone (MOPP) cycles and the extent of irradiation on the risk of secondary acute nonlymphocytic leukemia (SANLL) after a single combined treatment for Hodgkin's disease (HD). Between April 1972 and May 1980, 462 patients with HD clinical stage (CS) I, II, and III were prospectively treated with three or six cycles of MOPP and supra- and/or infradiaphragmatic irradiation (40 Gy). Four hundred forty-one patients achieved complete remission (CR). By January 1988, 237 patients had been followed-up in first CR for at least 10 years. Ten patients developed SANLL between the 34th and 123rd month of CR. The 15-year SANLL risk is 3.5% +/- 2.7%. Cox's stepwise regression analysis performed with all initial and treatment covariates (sex, age, histology, splenectomy, MOPP chemotherapy, and irradiation extent) showed that the only significant explanatory variable of SANLL risk was the irradiation extent (P less than .002). Using the log-rank test, SANLL risk ranged from 2.2% for supradiaphragmatic irradiation alone to 9.1% for subtotal (STNI) or total nodal irradiation (TNI) (P less than .001). These results strongly suggest that extended high-dose irradiation and MOPP chemotherapy should not be combined for the treatment of HD.