Evaluation of cases with over 10 years of follow-up after stereotactic body radiotherapy for Stage I lung cancer.

Abstract

PurposeStereotactic body radiotherapy (SBRT) is a well-established treatment for early stage non-small cell lung cancer (NSCLC); however, outcomes beyond 10 years remain poorly defined. We aimed to evaluate late toxicities, recurrence patterns, and secondary malignancies in patients with ≥10 years of follow-up after SBRT.Methods and materialsAmong 246 patients treated with SBRT for histologically confirmed NSCLC or clinically diagnosed lung cancer (≤5 cm) between 2001 and 2014 at our institution, 44 patients with follow-up exceeding 10 years were retrospectively analyzed. Clinical records and imaging data, including those from external institutions, were reviewed to assess late toxicity, recurrence, and secondary malignancies. Descriptive analyses focused on long-term survivors.ResultsMedian clinical and imaging follow-up durations were 143 months (range: 120-202) and 128 months (range: 60-199), respectively. The median patient age was 77 years (range: 58-86), and 68% underwent histological confirmation. Prescribed doses ranged from 40-70 Gy delivered in 4-10 fractions. At the last follow-up, 19 patients had died: 2 from lung cancer, 16 from other causes, and 1 from treatment-related empyema. The following three atypical late toxicities emerged beyond 10 years: bronchial stenosis/obstruction with secondary infection (grade 5), chest wall mass formation simulating malignancy (grade 3), and pericardial inflammation (grade 3). One patient died from an acute exacerbation of interstitial lung disease following repeat SBRT for a second primary lung cancer. Recurrence occurred in five patients, including three local failures observed beyond 5 years; no recurrences occurred after 10 years. No radiation-induced malignancies were identified.ConclusionsThis long-term analysis identified several late toxicities not evident during standard follow-up, no local failures beyond 10 years, and no radiation-induced secondary malignancies. Although limited by the small sample size and survivorship bias, these findings underscore the importance of extended surveillance and provide insight into the very late effects of SBRT.