PROPHYLACTIC CRANIAL IRRADIATION IN COMPLETE RESPONDERS WITH SMALL-CELL LUNG-CANCER - ANALYSIS OF THE MAYO-CLINIC AND NORTH-CENTRAL-CANCER-TREATMENT-GROUP DATA-BASES

Purpose: To determine whether prophylactic cranial irradiation (PCI) h as an impact on brain failure and survival in patients with small-cell lung cancer (SCLC) who have achieved a complete response to chemother apy with or without thoracic radiation therapy (TRT). Methods: Between 1975 and 1990, the Mayo Clinic and North Central Cancer Treatment Gro up entered 1,617 patients on 15 phase II and III SCLC protocols of che motherapy with or without TRT and PCI. Results: Of 772 patients with l imited disease, 457 (59%) achieved a complete response, compared with 200 of 845 patients (24%) with extensive disease. With follow-up durat ions of 2 to 17 years (median, 4), the median survival time and 2-, 5- , and 10-year survival rates for the 457 completely responding limited -disease (LD-CR) patients were 19.6 months, 41%, 17%, and 5%, compared with 13.9 months, 26%, 8%, and 5%, respectively, for the 200 complete ly responding extensive disease (ED-CR) patients (P = .0001). Multiple prognostic factors, including whether the patient did or did not rece ive PCI (30 to 38 Gy in 2- to 3.6-Gy fractions) were analyzed. In both univariate and multivariate analyses, PCI was not associated with imp roved (or worsened) survival. The brain relapse rate was 37% for LD-CR patients who did not receive PCI versus 9% for those who did (P = .00 01). In ED-CR patients, the brain relapse rate was 31% without PCI and 8% with (P = .009). Essentially all patients who developed brain rela pse died within 2 years, with a median survival time of 3,7 months fol lowing relapse. Severe, life-threatening, or fatal CNS toxicity occurr ed in approximately 3% of patients who received PCI. Conclusion: The u se of PCI remains controversial outside the setting of a clinical tria l. (C) 1994 by American Society of Clinical Oncology.