Treatment and outcome trends and predictors of overall survival of rectal melanoma: Analysis of the National Cancer Database

Background: We aimed to assess characteristics, treatment, and outcomes of rectal melanoma (RM). Methods: This retrospective cohort study looked at patients with RM from National Cancer Database (2004–2019) analyzed characteristics and outcomes of the entire cohort and across three time periods (2004–2009; 2010–2014; 2015–2019). Main outcome measures were change in treatment and survival trends across time periods and overall survival (OS). Results: 641 patients (58.5% female; mean age: 68.2 ± 13.6 years) were included. OS rate was 26%; median survival duration was 17.9 (IQR: 15.93–20.67) months. There was a significant decrease in the use of chemotherapy (17.3%–6.6%; p = 0.001) and surgery (62.9%–41.8%; p = 0.00004) but increased use of immunotherapy (11.9%–52%; p < 0.001) across time periods. OS was longer in the last time period than in the first two (21.8 vs 16.8 vs 16.5 months; p = 0.09). Surgical excision was an independent predictor of improved OS (HR = 0.266, 95%CI: 0.089–0.789, p = 0.017) whereas older age (HR = 1.039, 95%CI: 1.007–1.072, p = 0.016), positive resection margins (HR = 5.06, 95%CI: 1.902–13.48, p = 0.001) and metastasis (HR = 34.62, 95%CI: 3.973–301.6, p = 0.001) were predictors of poor survival. Conclusions: Over time, chemotherapy and surgery have been used less often in the treatment of RM while the use of immunotherapy increased by more than four-fold. Older age, surgical treatment, positive resection margins, and metastasis were predictive of survival of RM.