Extensive surgery and lymphadenectomy do not improve survival in primary melanoma of the anorectum: results from analysis of a large database (SEER).

AIM: Primary anorectal melanoma is a rare disease with a dismal prognosis due to early distant metastasis. The prognostic value of positive loco-regional lymph nodes and the impact of lymphadenectomy on overall survival are unclear. We have investigated this by analysis of data obtained from a national representative database, controlling for potential confounders.

METHODS

Data were retrieved from the Surveillance, Epidemiology and End Results (SEER) database. Multiple imputation analysis was performed to deal with missing data. Cox regression models were formulated using different prognostic factors including site of origin, gender, size, race, rate of lymph node metastasis (ratio between positive lymph node count and total lymph nodes harvested), extent of lymphadenectomy (none, level I etc.), age, type of surgery, stage of disease and administration of radiotherapy.

RESULTS

Our population was composed of 208 patients who underwent surgery between 1998 and 2012. Rate of lymph node metastasis (P = 0.027; hazard ratio 1.873, 95% CI 1.076-3.261) and race (P = 0.019; hazard ratio 2.291, 95% CI 1.148-4.575) were found to be independent predictors of survival.

CONCLUSION

Based on the data retrieved from the SEER database, metastasis to loco-regional lymph nodes is an important prognostic factor, but lymphadenectomy does not improve survival.