Low doses of prophylactic cranial irradiation effective in limited stage small cell carcinoma of the lung

Abstract

Purpose: Prophylactic cranial irradiation (PCI) for the prevention of brain metastasis in small cell lung cancer remains controversial, both in terms of efficacy and the optimal dose-fractionation scheme. We performed this study to evaluate the efficacy of PCI at low doses.

Methods and materials: One hundred and ninety-seven patients were referred to our institution for treatment of limited stage small cell carcinoma of the lung between June 1986 and December 1992. Follow-up ranged from 1.1 to 89.8 months, with a mean of 19 months. Eighty-five patients received PCI.

Results: Patients receiving PCI exhibited brain failure in 15%, while 38% of untreated patients developed metastases. This degree of prophylaxis was achieved with a median total dose of 25.20 Gy and a median fraction size of 1.80 Gy. At these doses, acute and late complications were minimal. Patients receiving PCI had significantly better 1-year and 2-year overall survivals (68% and 46% vs. 33% and 13%). However, patients with a complete response (CR) to chemotherapy and better Karnofsky performance status (KPS) were overrepresented in the PCI group. In an attempt to compare similar patients in both groups (PCI vs. no PCI), only patients with KPS > or = 80, CR or near-CR to chemotherapy, and treatment with attempt to cure, were compared. In this good prognostic group, survival was still better in the PCI group (p = 0.0018).

Conclusion: In this patient population, relatively low doses of PCI have accomplished a significant reduction in the incidence of brain metastasis with little toxicity. Whether such treatment truly improves survival awaits the results of additional prospective randomized trials.