Considerations on radiotherapy dose intensity for limited small cell lung cancer

The factors of dose, volume, fractionation, and timing with chemotherapy undoubtedly influence outcomes in terms of treatment of limited small cell lung cancer with thoracic radiotherapy. The type and timing with chemotherapy may be very important. For integration of chemotherapy with radiation therapy, the measure of iso-effects, for tumor and acute tissue and late effects, may be hard to come by. This paper relates a variety of different total doses, according to the relative scales provided by nominal standard dose (NSD, NRET) and the biologic effective dose (Gy-10 and Gy-3), which employs the alphabeta linear quadratic model. A variety of different fraction schemes have been used clinically. These allow us to compare intensifying of the dose versus standard treatment versus relative prolongation of the dose. When defined as measure of 2-year survivals, there is not a tremendous difference in observed outcomes. However, there may be differences that are discerned later when the endpoint local control is examined. This paper reviews the current pilot studies using platinum-etoposide chemotherapy, at a variety of different dose-intensive regimens of thoracic radio-therapy and their relative effects. To prove benefit, randomized trials are needed.