RADIOTHERAPY-ASSOCIATED NEUTROPENIA AND THROMBOCYTOPENIA - ANALYSIS OF RISK-FACTORS AND DEVELOPMENT OF A PREDICTIVE MODEL

Risk factors for unscheduled interruptions in radiotherapy courses com pleted between June 1989 and August 1995, lasting greater than or equa l to 2 days, and associated with World Health Organization grade Ill-I V neutropenia or thrombocytopenia were studied retrospectively. A grou p of controls was randomly selected. Potential risk factors for myelos uppression were analyzed using univariate and multivariate analyses. T he most important risk factors for treatment interruption with thrombo cytopenia were concurrent chemotherapy (odds ratio [OR], 45.5; P <.001 ), increasing percentage of marrow irradiated (OR, 4.1 for each 20%; P <.001), and brain metastases (OR, 7.3; P =.01). Other significant (P <.05) factors were leukemia/lymphoma, bone or bone marrow metastases, and prior chemotherapy. The most important risk factors for treatment interruptions with neutropenia were concurrent chemotherapy (OR, 42.1; P <.001) and increasing percentage of marrow irradiated (OR, 3.3 for each 20%; P <.001). Similarly, the most important risk factors for tre atment interruptions with both thrombocytopenia and neutropenia were c oncurrent chemotherapy (OR, 48.6; P <.001) and increasing percentage o f marrow irradiated (OR, 3.9 for each 20%; P <.001). Other significant (P <.05) factors in these groups were bone marrow or brain metastases and previous chemotherapy. These data were used to create a model, as signing patients to groups at high, intermediate, or low risk for trea tment interruption with thrombocytopenia. High-risk patients may be ca ndidates for clinical trials of a platelet growth factor, (C) 1997 by The American Society of Hematology.