Prophylactic cranial irradiation for limited-stage small-cell lung cancer in the modern magnetic resonance imaging era may be omitted: a propensity score-matched analysis

Abstract

We aimed to clarify whether prophylactic cranial irradiation (PCI) is associated with improved outcomes in limited-stage small-cell lung cancer (LS-SCLC) in the current era of magnetic resonance imaging (MRI). Data from patients with LS-SCLC who achieved a complete response to definitive chemoradiotherapy (CRT) at two medical centers were retrospectively reviewed. Propensity score-matching was performed in a 2:1 ratio to balance the baseline characteristics of the no-PCI and PCI groups. The endpoints were the incidence of brain metastasis (BM), neurological causes of death and overall survival (OS). Overall, 80% patients underwent head MRI during the initial staging and 75 patients (no-PCI, n = 50; PCI, n = 25) were matched. Their baseline characteristics were generally well-balanced except for age; patients in the no-PCI group tended to be older. The median follow-up period was 29 months. Although the incidence of BMs tended to be higher in the no-PCI group (1-year BM occurrence: 26% vs 17%, P = 0.22), the incidence of multiple BMs (defined as >4 metastases) was similar between groups (1-year multiple BMs occurrence: 8% vs 9%, P = 0.65). The 2-year neurological causes of death and OS rate did not significantly differ between the groups (6% and 9%; P = 0.85; and 70% and 79%; P = 0.36, respectively). The 1-year occurrence of multiple BMs did not increase, even without PCI, when modern imaging modalities were integrated into the initial diagnosis, suggesting that PCI could be omitted after CRT, if MRI was incorporated into the initial diagnosis and follow-up.

Keywords: limited-stage small-cell lung cancer; magnetic resonance imaging; propensity score-matched analysis; prophylactic cranial irradiation.

Fig. 1

Clinical outcomes of the entire cohort with or without PCI. Cumulative incidence of BMs (a), oligo-BMs (b), multiple BMs (c) and neurological cause of death (d) after definitive treatment. Kaplan–Meier curves of progression-free (e) and overall (f) survival after definitive treatment.

Fig. 2

Clinical outcomes of the propensity score-matched cohort with or without PCI. Cumulative incidences of BMs (a), oligo-BMs (b), multiple BMs (c) and neurological causes of death (d) after definitive treatment. Kaplan–Meier curves of progression-free (e) and overall (f) survival after definitive treatment.