Effects of brain irradiation and chemotherapy on myelosuppression in small-cell lung cancer

The effect of brain irradiation on myelosuppression was studied in patients with untreated small-cell lung cancer (SCLC) by comparing 24 patients who received brain irradiation for brain metastasis at presentation (irradiated patients) with 24 control patients who were selected by matching ages and non-CNS metastatic sites with those of irradiated patients. All patients were evaluated during the first three courses of chemotherapy. More irradiated patients than control patients had chemotherapy dose reductions from the starting dose level for the second (nine of 22 v two of 24; P = .03) and the third (nine of 18 v three of 20; P = .05) courses of chemotherapy. Overall, more irradiated patients had chemotherapy dose reductions than did control patients (11 of 22 v three of 24; P = .01). The difference was highly significant even after other variables were considered in a multivariate analysis (P less than .001). Myelosuppression was more severe in irradiated patients for WBCs (P = .01) and for platelets (P = .05). When the second course of chemotherapy was administered at the same dose levels as in the first course, irradiated patients had greater decreases in nadir counts after the second course compared with the first course than did control patients. Irradiated patients had a higher incidence of infectious complications than did control patients (14 of 24 v six of 24; P = .02), particularly after the second course of chemotherapy (seven of 22 v one of 24; P = .04). There were four treatment-related deaths due to sepsis in irradiated patients. Following brain irradiation given concurrently with intensive chemotherapy, close monitoring of myelosuppression and adjustments of chemotherapy doses are advised.