A retrospective study of clinicopathologic and molecular features of inoperable early-stage non-small cell lung cancer treated with stereotactic ablative radiotherapy

Abstract

Stereotactic ablative radiotherapy (SABR) is the treatment of choice for medically inoperable, early-stage non-small cell lung cancer (ES-NSCLC). The influence of oncogenic driver alterations and comorbidities are not well known. Here we present treatment outcomes based on clinicopathologic features and molecular profiles. We retrospectively analyzed patients treated with SABR for inoperable ES-NSCLC. Molecular features of oncogenic driver alterations included EGFR, ALK, and ROS1. Comorbidities were assessed using the age-adjusted Charlson Comorbidity Index (ACCI). Survival was calculated using the Kaplan-Meier method. The Cox regression model was performed for univariate and multivariate analyses of prognostic factors. Competing risk analysis was used to evaluate the cumulative incidence of disease progression. From 2008 to 2020, 100 patients (median age: 82 years) were enrolled. The majority of patients were male (64%), ever-smokers (60%), and had adenocarcinoma (65%). With a median follow-up of 21.5 months, the median overall survival (OS) and real-world progression-free survival were 37.7 and 25.1 months, respectively. The competing-risk-adjusted 3-year cumulative incidences of local, regional, and disseminated failure were 8.2%, 14.5%, and 31.2%, respectively. An ACCI ≥7 was independently associated with inferior OS (hazard ratio [HR] 2.45, p=0.03). Tumor size ≥4cm (HR 4.16, p<0.001) was the most important independent prognostic factor predicting real-world progression. EGFR mutation status had no impact on the outcomes. SABR provides excellent local control in ES-NSCLC, although disseminated failures remains a major concern. ACCI is the best indicator for OS, while tumor sizes ≥4cm predicts poor disease control.