Local control correlates with overall survival in radiotherapy for early-stage non-small cell lung cancer: A systematic review.

PURPOSE: Local control (LC) is an important outcome of local cancer therapy, besides overall survival (OS). We conducted a comprehensive literature search to investigate whether a high LC rate contributes to good OS in radiotherapy for early-stage non-small cell lung cancer (ES-NSCLC). MATERIALS AND METHODS: Studies in patients receiving radiotherapy for peripheral ES-NSCLC, mainly staged as T1-2N0M0 were included for a systematic review. Relevant information was collected including, dose fractionation, T stage, median age, 3-year LC, cancer-specific survival (CSS), disease-free survival (DFS), distant metastasis-free survival (DMFS), and OS. Correlations between outcomes and clinical variables were evaluated. RESULTS: After screening, 101 data points from 87 studies including 13,435 patients were selected for the quantitative synthesis. Univariate meta-regression analysis revealed that the coefficients between the 3-year LC and 3-year DFS, DMFS, CSS, and OS were 0.753 (95% confidence interval (CI): 0.307-1.199; p < 0.001), 0.360 (95% CI: 0.128-0.593; p = 0.002), 0.766 (95% CI: 0.489-1.044; p < 0.001), and 0.574 (95% CI: 0.275-0.822; p < 0.001), respectively. Multivariate analysis revealed that the 3-year LC (coefficient, 0.561; 95% CI: 0.254-0.830; p < 0.001) and T1 proportion (coefficient, 0.207; 95% CI: 0.030-0.385; p = 0.012) were significantly associated with the 3-year OS and CSS (coefficient for 3-year LC, 0.720; 95% CI: 0.468-0.972; p < 0.001 and T1 proportion, 0.002; 95% CI: 0.000-0.003; p = 0.012). Toxicities ≥ grade 3 were low (3.4%). CONCLUSIONS: Three-year LC was correlated with three-year OS in patients receiving radiotherapy for ES-NSCLC. A 5% increase in 3-year LC is expected to improve the 3-year CSS and OS rates by 3.8% and 2.8%, respectively.