Use of hemibody irradiation as a non-cross-resistant agent in combination with systematic chemotherapy in small cell lung cancer.

Previously, investigators at this institute have studied the use of upper hemibody irradiation as a consolidation agent following combination chemotherapy for small cell lung cancer. There was no improvement in survival compared to that in the group treated with chemotherapy alone. In our present pilot study, we are investigating the toxicity and efficacy of using hemibody irradiation (HBI) as a non-cross-resistant agent early in a program of alternating chemotherapy consisting of six treatment cycles. Toxicity due to the combined effects of chemotherapy (cisplatin and etoposide plus cyclophosphamide, doxorubicin, and vincristine) plus HBI is reported. The HBI was given at a dose of 1,000 cGy in four fractions for limited disease or as a single 800-cGy dose for extensive disease. Bone marrow suppression following HBI necessitated a subsequent delay in the chemotherapy cycle or dose reduction in 55% of the 33 patients. Six patients developed diffuse interstitial pneumonitis following chemotherapy and HBI; 3 have died, and in 2 of these, the etiology was opportunistic infection. In our previous studies utilizing HBI either alone or as consolidation therapy after induction chemotherapy, a low incidence of lung toxicity occurred. This increased incidence suggests a possible drug-radiation interaction when HBI is used as an alternating agent with doxorubicin and cisplatin.