Immunotherapy In Combination With Surgery And Radiation Improves Local Control For Primary Mucosal Melanomas

Mucosal melanoma is a rare disease with a poor prognosis. Given the lack of prospective randomized trials, management is extrapolated from the cutaneous melanoma literature. Historically, surgical resection has been the primary treatment. Retrospective reviews suggest adjuvant radiation therapy after surgery improves local control. We assessed if adding immunotherapy after surgical resection and radiation therapy further improves tumor control. We identified 46 patients treated for mucosal melanoma at a single institution from 2000-2017 under an institutional review board (IRB) approved protocol. Patient characteristics and treatment outcomes were collected. Outcomes were measured from the date of surgery using the Kaplan-Meier Method and compared using log-rank tests. The median follow up was 41 months. The majority of patients had pathological stage T3 or T4 disease (97.8%). The most frequently involved site was head and neck (73.9%). Nine patients received immunotherapy after completing surgery followed by radiotherapy. Twelve patients underwent surgical resection alone. Twenty-five patients underwent surgery followed by radiotherapy for treatment. The median age at time of surgery was 67. Margins were positive in 23.9% of cases. At 5 years, there was a local recurrence free survival benefit for those who received immunotherapy in combination with radiotherapy and surgery (46.7%) as compared to those who underwent surgery alone (0%) or followed by adjuvant radiotherapy (41.1%), (p = 0.018). There was no statistically significant difference in overall survival or distant metastases between the three arms (p = 0.904 and p = 0.415, respectively). We did not observe unexpected increased toxicity with the addition of immunotherapy to radiotherapy and surgery. Adding immunotherapy after surgery and radiation therapy may improve local control compared to surgery alone with or without adjuvant radiation therapy. The observed toxicities from trimodality therapy appeared to be acceptable. However, prospective trials are needed to further investigate the optimal treatment paradigm for mucosal melanomas.