Gastrointestinal melanoma: Outcomes of surgery and immunotherapy.

Abstract

e16224 Background: Most knowledge on gastrointestinal (GI) melanoma is limited to anal melanoma. Our aim is to examine the impact of surgical treatment and the utility of immunotherapy on GI (other than anal) melanoma. Methods: The National Cancer Database (2004-2016) was reviewed for patients who were treated for GI melanoma. Kaplan-Meier method and log-rank test were used to make survival comparisons. Results: We analyzed data from 731 patients with gastrointestinal melanoma (esophageal:97, gastric:57, small bowel:87, colonic:31, rectal:459). A minority of patients had metastatic disease at the time of diagnosis (esophageal:14.4%, gastric:17.5%, small bowel:4.6%, colonic:19.4%, rectal: 16.3%) and small proportion received immunotherapy (esophageal:16.5%, gastric:15.8%, small bowel:15%, colonic:6.5%, rectal:20.3%). Patients who had resection with negative margins had an improved survival irrespectively of the magnitude of surgery (for example rectal melanoma: OS: no surgery:7.9mo, local excision:23.3mo, partial proctectomy:23.5mo, total proctectomy:18.4mo; p < 0.001 and OS for R0 margins:29.4mo vs R1:13.5mo vs R2:5mo;p < 0.001). The use of immunotherapy was associated with improved survival in metastatic disease for rectal melanoma (OS:10.8mo vs 5.7mo; p = 0.01). Conclusions: Excision with negative margins is associated with improved outcomes in gastrointestinal melanoma. The use of immunotherapy should be considered in the presence of metastatic disease.