Rectal melanoma: epidemiology, prognosis, and role of adjuvant radiation therapy

Purpose: Rectal melanoma (RM) is a lethal malignancy which is not well understood. While cases are rising, data concerning effective management are limited. The present paper sought to elucidate the epidemiology and prognosis of RM, while also analyzing the role of adjuvant radiation therapy (RT). Methods: We used the surveillance, epidemiology, and end results program to find all cases of RM diagnosed between 2004 and 2011. Patients 18 or older with non-metastatic disease who had undergone surgery were included. Data regarding the age, race, sex, marital status, stage, and radiation sequence with surgery were extracted from the database and analyzed. Disease-free (DFS) and overall survival (OS) was studied for the group overall and between subgroups. Results: Median age at diagnosis was 69 years. RM is significantly more common in whites compared to nonwhites and occurs equally in males and females. Most patients are diagnosed at an early stage. Prognosis is poor with a median DFS of 27 months and median OS of 22 months. There were no differences in outcomes based on age, sex, marital status, or stage; however, OS was improved in nonwhites as compared to whites (P = 0.04). RT did not improve DFS (27 vs 28 months for surgery vs surgery and radiation, P = 0.82) or OS (19 vs 22 months for surgery vs surgery and radiation P=0.80) regardless of stage. Conclusions: RM is an aggressive disease primarily affecting older, white patients. RT does not improve survival, regardless of stage. Optimal management of this lethal disease remains to be elucidated.