Prophylactic cranial irradiation in small-cell lung cancer.

Prophylactic cranial irradiation is now known to improve survival to a significant degree in small-cell lung cancer (SCLC) patients; this is in addition to its established role in preventing the disabling symptoms of brain metastases. New information indicates that it confers a survival benefit for limited or extensive stage SCLC patients gaining a complete response in the chest. A review of causes of cerebral dysfunction as a complication indicates that such problems can be due to suboptimal radiation fractionation, chemotherapy, or an inappropriate combination of prophylactic brain irradiation with chemotherapy. Optimum treatment with prophylactic brain irradiation has been shown not to cause adverse effects with detailed psychometric testing. Several additional sources of information can be drawn together to suggest a dose-response pattern for prophylactic brain irradiation, leading to the recommendation that a dose of 25-36 Gy is optimal, delivered in 2-3 Gy daily fractions after the completion of chest irradiation and chemotherapy. This will be better defined in future clinical trials.