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.

ABSTRACT

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.