High Lymph Node Positive to Sampled Ratio as a Potential Indication for Postoperative Radiation Therapy in Patients with pN2 Non-small-cell Lung Cancer

Despite advances in cancer treatment and screening, lung cancer remains the leading cause of cancer death in the United States [1]. The majority of cases are locally advanced non-small cell lung cancer (NSCLC), treatment of which usually includes a bior tri-modality therapy utilizing a combination of surgery, chemotherapy, and radiation therapy. For patients initially treated with surgery, use of postoperative radiation therapy (PORT) for completely resected NSCLC has remained controversial since the initial publication of the PORT meta-analysis in 1998 [2]. Stewart et al. reported an overall detriment of PORT on overall survival (OS), which was proposed to be linked to factors outside of inferior cancer control, such as adverse treatment effects. However, no clear impairment to OS existed in patients found to have mediastinal lymph node involvement (pN2), leading to multiple single-institution and database registry analyses investigating this question. These studies are limited by indication bias inherent to retrospective design, but provided justification of continued use of PORT in pN2 disease. Despite absence of high-level evidence, PORT has remained standard of care for this subset of NSCLC due to benefits in locoregional control and OS as indicated by American Society for Radiation Oncology (ASTRO) practice guidelines [3]. Abstract