The role of prophylactic cranial irradiation for patients with small-cell lung cancer.

Small-cell lung cancer (SCLC) has a particular propensity to metastasize to the brain, affecting ~10% of SCLC patients at diagnosis, but may occur in more than 50% of 2-year survivors. Most cytotoxic drugs have limited ability to cross the blood-brain barrier, and the effectiveness of chemotherapy for brain metastasis is limited. Therefore, prophylactic cranial irradiation (PCI) has been proposed to treat SCLC. A meta-analysis revealed that PCI significantly decreased the risk of brain metastasis and increased the 3-year survival rate; it has been established as a standard therapy for limited-disease SCLC. However, certain aspects of PCI remain unclarified, including the roles in resected SCLC and extensive-disease SCLC, and its neurotoxicities. In addition, information on PCI has been obtained from old clinical trials without the use of new imaging devices, such as magnetic resonance imaging. Evidence from advanced imaging techniques is needed in this era.