The benefit of prophylactic cranial irradiation (PCI) in limited-stage small-cell lung cancer (LS-SCLC) was established in a meta-analysis performed in 1999. Since then, considerable progress has been made in the diagnosis, staging and treatment of LS-SCLC, including chemotherapy and radiotherapy, which led to a longer survival time in patients. Therefore, the magnitude of the benefit of PCI should be re-evaluated. Furthermore, the optimum timing of PCI for LS-SCLC treatment has not been established and more data is required to demonstrate this. In the present retrospective study, the cases of patients that were diagnosed with LS-SCLC between March 2005 and December 2010 were reviewed. The main eligibility criteria of patients were a diagnosis of LS-SCLC and the achievement of a complete response (CR) or near CR subsequent to receiving ≥3 cycles of cisplatin-based chemotherapy, with or without advanced thoracic radiotherapy. Early and late PCI groups were separated using the median time interval between the start of primary chemotherapy and the start of PCI. In total, 80 patients were excluded from the analysis, including 9 patients that developed brain metastases, 2 during primary chemotherapy and 7 during radiotherapy. The remaining 399 patients were deemed eligible. PCI was administered to 185 patients; 92 patients were in the early PCI group and 93 were in the late PCI group. PCI significantly decreased the incidence of brain metastases [P<0.001; HR, 0.24; 95% confidence interval (CI), 0.15-0.39] and improved the overall survival time of the patients (median survival time, 21.5-38.8 months; P<0.001; HR, 0.60; 95% CI, 0.45-0.79). However, no significant difference was identified between the early and late PCI groups, either in the incidence of brain metastases (P=0.875) or the overall survival time (P=0.361). Multivariate analysis revealed that PCI (P=0.004) and thoracic radiotherapy (P=0.023) were the only 2 independent favorable prognostic factors of overall survival time. The present study demonstrates that PCI may be of considerable benefit to increase the survival rate and time of patients, and early PCI is as effective as late PCI. However, the present study recommends that PCI should be offered as soon as primary chemotherapy is completed, since there is a greater risk of developing brain metastases during thoracic radiotherapy.
Keywords: brain metastases; limited-stage small cell lung cancer; overall survival; prophylactic cranial irradiation.