LAUSR

9558 Background: Immunotherapy (IMT) for stages-III and IV melanoma has dramatically changed overall prognosis and treatment strategies. The aim of this study was to evaluate if use of IMT significantly changed the likelihood of regional/distant lymph node (LN) resection and surgical resection for distant metastases (DM) among patients with stages-III and IV melanoma, respectively, in the pre- and post-2011 era. Methods: The National Cancer Database (2004-2015) was used to evaluate the likelihood of regional/distant LN resection and surgical resection for DM among patients with stages-III and IV melanoma, respectively, with use of IMT. Multivariable stepwise with forward selection Poisson regression with robust standard errors was used to adjust for potential confounders (age, gender, race, year of diagnosis, Charlson-Deyo Score, facility type, facility location, insurance status, 2012 median income quartile, and 2013 urban/rural status). A stratified analysis was performed to evaluate differences among facility type. Results: There were 28,847 patients (median age 62 (IQR 53-73); 36.3% female) with stage-III melanoma and 14,443 patients (median age 66 (IQR 56-76); 31.7% female) with stage-IV melanoma. Overall, 24.3% (n = 7,018) and 17.0% (n = 2,459) with stage-III and IV melanoma, respectively, received IMT. The adjusted relative risk (aRR) of regional/distant LN resection among patients with stage-III melanoma was significantly higher with use of IMT (aRR 1.16, 95% CI 1.05–1.28, P = 0.004), while the aRR of surgical resection for DM was significantly lower with use of IMT for stage-IV melanoma (aRR 0.85, 95% CI 0.78–0.92, P < 0.001). Stratified analysis demonstrated that the findings were principally reflective of academic/research hospitals. Conclusions: The higher likelihood of regional/distant LN resection in stage-III melanoma may be due to the curative role of surgery and preceded the post-MSLT-II era. Conversely, in stage-IV melanoma, surgery may be limited to resectable oligometastatic disease given the durable and systemic benefit of first-line IMT.