The therapeutic effect of radiotherapy combined with systemic therapy compared to radiotherapy alone in patients with simple brain metastasis after first-line treatment of limited-stage small cell lung cancer: a retrospective study

Abstract

Abstract Purpose We aimed to compare the therapeutic effect of radiotherapy (RT) plus systemic therapy (ST) with RT alone in patients with simple brain metastasis (BM) after first-line treatment of limited-stage small cell lung cancer (LS-SCLC). Methods The patients were treated at a single center from January 2011 to January 2022. BM only without metastases to other organs was defined as simple BM. The eligible patients were divided into RT alone (monotherapy arm) and RT plus ST (combined therapy arm). Univariate and multivariate Cox proportional hazards analyses were used to examine factors associated with increased risk of extracranial progression. After 1:1 propensity score matching analysis, two groups were compared for extracranial progression-free survival (ePFS), PFS, overall survival (OS), and intracranial PFS (iPFS). Results 133 patients were identified and 100 were analyzed (monotherapy arm: n = 50, combined therapy arm: n = 50). The ePFS of the combined therapy was significantly longer than that of the monotherapy, with a median ePFS of 13.2 months (95% CI, 6.6–19.8) in combined therapy and 8.2 months (95% CI, 5.7–10.7) in monotherapy (P = 0.04). There were no statistically significant differences in PFS (P = 0.057), OS (P = 0.309), or iPFS (P = 0.448). Multifactorial analysis showed that combined therapy was independently associated with better ePFS compared with monotherapy (HR = 0.617, P = 0.034); more than 5 BMs were associated with worse ePFS compared with 1–5 BMs (HR = 1.808, P = 0.012). Conclusions Compared with RT alone, combined therapy improves ePFS in patients with simple BM after first-line treatment of LS-SCLC. Combined therapy and 1–5 BMs reduce the risk of extracranial recurrence.