Impact of surgical treatment on survival in patients with primary rectal melanoma

Abstract

19001 Background: Reports of melanoma of the lower GI tract, especially in the rectal area, were often grouped with diseases from the anal canal region. Outcome and pattern of care regarding primary melanoma of the rectum only were not well described in the literature. This review examined the utilization of surgery, radiotherapy (RT), and the potential impact on survival outcome in this subgroup of patients. Methods: The Surveillance, Epidemiology, and End Results (SEER) database (1973 to 2003) was searched. Only patients with primary melanoma of the rectum (excluding anal lesions) with recordable pathology reports were included. 79 patients were identified. 61 of them had melanoma of the rectum as the sole primary disease, and these patients were the focus of this study. Kaplan Meier estimation and Cox-Mantel test were used to calculate and compare survival rates. Results: Among the 61 patients, 20 patients did not have further surgery after biopsy. Another 20 patients had surgery, but the types of procedure were unknown. Of the remaining 21 patients eligible for analysis, eight patients had abdominoperineal resection (APR), and one of them received postoperative RT. Thirteen patients had partial proctectomy (PP), and none had RT. In univariate analysis, the 5-year overall survival rates for APR and PP groups were 12.5% and 7.7% respectively (p=0.63). There were one survivor in each group at the last follow up period with crude survival time of 15 years and 13.5 years respectively. More patients in APR group had locoregional disease (extramural and nodal) than in PP group (63% versus 0% respectively) at diagnosis. Comparing the time intervals by decade between 1973 to 1982, 1983 to 1992, and 1993 to 2003 in all 61 patients, use of postoperative RT was relatively limited at 1 in 14 cases, 1 in 19 cases, 2 in 28 cases respectively. RT was used mostly in patients who were not candidate for surgery and in patients with metastatic disease at diagnosis presumably for palliation. Conclusions: Primary melanoma of the rectum is a rare disease. Data for analysis were limited. There was no significant difference in overall survival between patients who had APR versus PP although APR group had higher tumor burden at diagnosis than PP group. Use of adjuvant RT is rare, and its role has yet to be further defined. No significant financial relationships to disclose.