Predictors of survival and recurrence patterns following definitive chemoradiotherapy in stage III non-small cell lung cancer-a retrospective cohort study.

Background: Chemoradiotherapy (CRT) is regarded as the treatment of choice for inoperable stage III non-small cell lung cancer (NSCLC) patients. Despite the curative intent, recurrence is frequent, and overall prognosis is poor. Thus, there is a need for clinical biomarkers to better predict outcome and to optimize treatment and follow-up. The aim of this study was to characterize a large cohort of real-world stage III NSCLC patients who received CRT with curative intent and to define parameters that could predict recurrence patterns, overall survival (OS) and survival time from recurrence.

Methods: This study is based on a cohort of 193 stage III NSCLC patients receiving CRT with curative intent in mid-Sweden during the years 2009-2018. Data was retrospectively collected from medical records. Clinical parameters, recurrence patterns, salvage treatment, histological and molecular data were analyzed and correlated to outcome.

Results: Median follow-up was 52 months, with a median OS of 33 months. Most patients (66%) progressed, commonly within the first 3 years following CRT. Performance status and common blood markers at recurrence were associated with worse survival. The presence of driver mutations [epidermal growth factor receptor (EGFR), Kirsten rat sarcoma viral oncogene homolog (KRAS)] or metastatic spread to N3 lymph nodes increased the risk of distant recurrence. Immunotherapy as salvage treatment was associated with a significantly better prognosis.

Conclusions: Routine diagnostic parameters can be used to predict survival and recurrence patterns in patients receiving curative CRT. Additionally, salvage treatment with immunotherapy was the strongest factor associated with longer survival after disease recurrence.