Prophylactic cranial irradiation in small cell lung cancer: rationale, results, and recommendations

The utility of prophylactic cranial irradiation (PCI) in patients with small cell lung cancer (SCLC) constitutes one of the longest running debates in oncology. Despite dozens of prospective and retrospective studies and decades of individual experience, a consensus has been reached on only two issues: (1) when administered to all patients with SCLC, PCI decreases the likelihood of developing brain metastases by about half, but (2) PCI does not significantly prolong survival. Uncertainty persists over many critical questions, including whether, when, and how to administer PCI; whether identifiable subgroups of patients benefit more tangibly from PCI; how frequent and severe the long-term side effects of PCI are; whether withholding treatment until brain metastases are diagnosed is clinically responsible and cost effective; and how newer forms of treatment for brain metastases should be integrated into the picture. In this review, we discuss the epidemiology and natural history of brain metastases in patients with SCLC, the results of studies examining the efficacy of PCI, data on the early and late toxicities of PCI, and the status of alternative therapies for patients with brain metastases from SCLC. Based on this information, an approach to newly diagnosed patients is suggested, and recommendations for future study are made.