Prophylactic cranial irradiation for patients with small cell lung cancer. An enduring controversy.

Small cell lung cancer (SCLC) is a systemic disease that usually presents with locally bulky disease in the lung and mediastinal nodes, with either subclinical (limited stage) or detectable (extensive stage) extrathoracic metastases. Treatment with local modalities alone leads almost invariably to systemic relapse, and treatment with only systemic therapy usually results in recurrence at sites of initially demonstrated disease. Although prophylactic cranial radiation is far from an ideal solution to the problem of CNS metastases in patients with SCLC, it presently seems preferable to the alternative of observation and generally ineffective palliative treatment at time of relapse in the CNS.