Metastatic Melanoma to the Small Bowel and Colon: A Systematic Review of the Global Experience and Institutional Cohort Analysis Detailing a Rare Clinical Entity

Abstract

Introduction: Cutaneous melanoma is among the most common solid tumors to metastasize to the gastrointestinal (GI) tract. Literature summarizing the clinical experience and features of this unique pathology is lacking.

Methods: A systematic review of the available literature reporting clinically salient features of melanoma metastases to the small and large intestines was conducted. Additionally, we surveyed our institutional experience of surgically treated melanoma metastasis to the small bowel and colon. A descriptive analysis was performed. Kaplan-Meier curves with log-rank tests were used to analyze time-to-event intervals. Univariable and multivariable Cox logistic regression models were generated to identify predictors of survival.

Results: Over 100 studies including 1153 patients were included. GI metastases predominantly affected males, were in the small bowel/jejunum, equally presented as solitary and multiple lesions, and were generally not the first site of distant metastatic disease. The median time from primary lesion diagnosis to GI metastasis was 48 months. Analysis of our institutional cohort suggested that survival in patients receiving complete GI-specific surgical resection and immune checkpoint inhibitors (ICIs) was prolonged compared to palliative resection and without ICI therapy. Positive prognostic factors for survival following GI metastasis included fewer GI metastatic lesions, complete resection, and longer duration between primary tumor diagnosis and GI metastasis.

Conclusions: GI metastases are a sign of advanced metastatic melanoma. Clinical suspicion of metastatic involvement in patients with a history of melanoma who develop any abdominal symptoms or anemia should remain high. Receipt of complete surgical resection and ICIs may prolong survival in disseminated melanoma.

Keywords: colon; immunotherapy; metastatic melanoma; small bowel; surgical resection.