Metastatic anorectal melanomas - An exploratory retrospective analysis on the benefits of systemic therapy versus best supportive care in a resource-limited setting from India

Survival following surgical treatment for anorectal melanoma seems similar for local excision and extensive resection regardless of nodal involvement

BACKGROUND

Anorectal melanoma is a rare malignancy with a dismal prognosis. The purpose of this study was to investigate whether the survival per stage is influenced by the surgical approaches (local excision or extensive resection), to assess prognostic factors of survival, and to answer the question whether the practiced surgical approaches changed over time.

METHODS

Dutch cancer registry organizations (IKNL and PALGA) were queried for all patients with a diagnosis of anorectal melanoma (1989-2019). Patients with disseminated disease at diagnosis were excluded. Survival outcomes were compared for the two surgical approaches stratified by stage (clinical node negative (cN0) and clinical node positive (cN+)) and date of diagnosis.

RESULTS

A total of 103 patients were included in this study. In both cN0 and cN+ patients the surgical strategy did not significantly influence survival (cN0: 21.7% 5-year survival, median 25 months for local excision versus 13.7% 5-year survival, median 17 months for extensive resection (p = 0.228), cN+: 11.1% 5-year survival for local excision, median 17 months versus 8.7% 5-year survival, median 14 months for extensive resection (p = 0.741)). Stage and date of diagnosis showed to be prognostic factors of survival. The ratio between the two surgical approaches was unchanged over three decades.

CONCLUSIONS

Extensive resection does not seem to improve survival in both cN0 and cN+ anorectal melanoma patients compared to local excision. However in the past three decades no shift towards local excision has been found. cN+ stage and an older date of diagnosis are predictors for worse survival.

Trends in the management of anorectal melanoma: A multi-institutional retrospective study and review of the world literature

BACKGROUND

Anorectal melanoma (ARM) is a rare disease with a poor prognosis. Evidence on optimal treatment is limited and surgical management varies widely. We hypothesized that the frequency of abdominoperineal resection used as primary treatment of ARM has decreased over the past several decades.

AIM

To update our understanding of outcomes for patients with ARM and analyze management trends around the world.

METHODS

This is a multi-institutional, retrospective study of patients treated for ARM at 7 hospitals. Hospitals included both large, academic, tertiary care centers and smaller, general community hospitals. Using prospectively maintained institutional tumor registries, we identified 24 patients diagnosed with ARM between January 2000 and May 2019. We analyzed factors prognostic for recurrence and survival. We then used Cox regression to measure overall survival (OS) and melanoma-specific survival. We also performed a literature review to assess trends in surgical management and outcomes.

RESULTS

Of the 24 patients diagnosed with ARM, 12 (50.0%) had local, 8 (33.3%) regional, and 4 (16.7%) distant disease at diagnosis. Median time to recurrence was 10.4 mo [interquartile range (IQR) 7.5-17.2] with only 2 patients (9.3%) not developing recurrence following surgical resection. Median OS was 18.8 mo (IQR 13.5-33.9). One patient is still alive without recurrence at 21.4 mo from diagnosis; no other patient survived 5 years. Primary surgical management with abdominoperineal resection (APR) vs wide excision (WE) did not lead to differences in OS [hazard ratio = 1.4 (95%CI: 0.3-6.8)]. Review of the literature revealed geographic differences in surgical management of ARM, with increased use of WE in the United States and Europe over time and more frequent use of APR in Asia and India. There was no significant improvement in survival over time.

CONCLUSION

There is wide variation in the management of ARM and survival outcomes remain poor regardless of approach. Surgical management should aim to minimize morbidity.