Association of Surgical Treatment, Systemic Therapy, and Survival in Patients With Abdominal Visceral Melanoma Metastases, 1965-2014: Relevance of Surgical Cure in the Era of Modern Systemic Therapy.

Importance: Systemic therapy for metastatic melanoma has evolved rapidly during the last decade, and patient treatment has become more complex. Objective: To evaluate the survival benefit achieved through surgical resection of melanoma metastatic to the abdominal viscera in patients treated in the modern treatment environment. Design, Setting, and Participants: This retrospective review of the institutional melanoma database from the John Wayne Cancer Institute at Providence St Johns Health Center, a tertiary-level melanoma referral center, included 1623 patients with melanoma diagnosed as having potentially resectable abdominal metastases before (1969-2003) and after (2004-2014) advances in systemic therapy. Main Outcomes and Measures: Overall survival (OS).
Results: Of the 1623 patients identified in the database with abdominal melanoma metastases, 1097 were men (67.6%), and the mean (SD) age was 54.6 (14.6) years. Of the patients with metastatic melanoma, 1623 (320 [19.7%] in the 2004-2014 period) had abdominal metastases, including 336 (20.7%) with metastases in the gastrointestinal tract, 697 (42.9%) in the liver, 138 (8.5%) in the adrenal glands, 38 (2.3%) in the pancreas, 109 (6.7%) in the spleen, and 305 (18.8%) with multiple sites. Median OS was superior in surgical (n = 392; 18.0 months) vs nonsurgical (n = 1231; 7.0 months) patients (P < .001). The most favorable 1-year and 2-year OS was seen after surgery for gastrointestinal tract (52% and 41%) and liver (51% and 38%) metastases, respectively. Multivariable analysis found increasing age (hazard ratio [HR], 1.01; 95% CI, 1.00-1.01; P = .02) and the presence of ulceration (HR, 1.21; 95% CI, 1.01-1.45; P = .04) were associated with a worse OS. Alternatively, treatment with metastasectomy (HR, 0.59; 95% CI, 0.46-0.74; P < .001) and metastases involving the gastrointestinal tract (HR, 0.65; 95% CI, 0.48-0.87; P = .004) were associated with a better OS. The systemic treatment era did not significantly affect outcomes (HR, 0.82; 95% CI, 0.67-1.02; P = .15). Overall, patients with gastrointestinal tract metastases undergoing complete, curative resection derived the greatest benefit, with a median OS of 64 months. Conclusions and Relevance: To our knowledge, this series is the largest single-institution experience with abdominal melanoma metastases, demonstrating that surgical resection remains an important treatment consideration even in the systemic treatment era.