Frailty has been shown to increase morbidity and mortality independent of age, but studies are lacking in radiation oncology. This study evaluates a modified frailty index (mFI) in predicting overall survival (OS) and non-cancer death for Stage I/II [N0M0] Non-Small-Cell Lung Cancer (NSCLC) patients treated with Stereotactic Body Radiation Therapy (SBRT).

Medical records for all patients with Stage I/II NSCLC treated at our institution with SBRT from 2009 to 2014 were reviewed. A validated mFI score, consisting of 11 variables was calculated, classifying patients as non-frail (0-1) or frail (≥2). Primary endpoint (OS) was analyzed using Kaplan-Meier method and log-rank. Secondary endpoint, non-cancer death, was analyzed using Fine-Gray's method, with death from lung cancer as a competing risk.

Patient cohort consisted of 38 (27.3%) non-frail and 101 (72.7%) frail [median total mFI score 3.0 (range 0-7)]. Median age and pack-year history was 74 and 46years, respectively. Median follow-up among survivors was 38.5months (range 4.0-74.1months). Frailty was associated with a lower 3-year OS (37.3% vs. 74.7%; p=0.003) and 3-year cumulative incidence of non-cancer death (36.7% vs. 12.5%; p=0.02). Frailty remained significant in the multivariate model [OS HR for mFI ≥2: 2.25 (1.14-4.44); p=0.02].

Frailty is associated with lower OS in older patients with early stage NSCLC treated with SBRT, yet frail patients survived a median 2.5years, and were more likely to die of causes unrelated to the primary lung cancer, suggesting SBRT should be considered even in older patients deemed unfit for surgery.