High-dose cyclophosphamide in small-cell carcinoma of the lung.

Eighteen patients with untreated small-cell cancer of the lung have been treated with cyclophosphamide 200 mg/kg on two occasions at an interval of four weeks. An additional eight patients received etoposide in addition to cyclophosphamide. Measurements of tumor volume were made by thoracic computed tomographic (CT) scan before and after each cycle. When compared with our previous study in which only one cycle of cyclophosphamide was given, the double procedure did not increase response rate, decrease the incidence of local relapse, or prolong the relapse-free interval. Survival after relapse was shorter with two cycles of chemotherapy mainly due to greater difficulty in administering further chemotherapy. The CT scans showed a decrease in tumor volume from 99.2 cc to 21 cc after the first cycle, but a smaller decrease to 14.1 cc after the second. These results show that the rapid emergence of drug resistance imposes limitations on the use of very high-dose cytotoxic chemotherapy.