Gynecological Cancer

PV 04 - Poster Viewing Q&A - Session 4

TU_46_2823 - Vulvar Melanoma: An Analysis of Prognostic Factors and Treatment Patterns

Tuesday, September 17
2:45 PM - 4:00 PM
Location: ASTRO Innovation Hub

Vulvar Melanoma: An Analysis of Prognostic Factors and Treatment Patterns
A. A. Albert, R. M. Allbright, and S. Vijayakumar; Department of Radiation Oncology, University of Mississippi Medical Center, Jackson, MS

Purpose/Objective(s): Melanoma comprises an estimated 5% to 10% of vulvar cancers and portends a worse prognosis as compared to squamous cell carcinoma of the vulva. The purpose of this study was to identify prognostic factors associated with survival for vulvar melanoma using the National Cancer Database (NCDB).

Materials/Methods: The NCDB was queried for patients with invasive vulvar squamous cell carcinoma and vulvar melanoma from 2004-2015. Demographic, clinical, and treatment details were compared via the Chi Square test between patients based on histology. Multivariable Cox regression and the Kaplan-Meier method were used to examine overall survival (OS).

Results: 31,408 patients met inclusion criteria including 29,131 (93.8%) patients with squamous cell carcinoma of the vulva and 1,917 (6.2%) patients with melanoma of the vulva. Median follow up time was 37 months. Patients with vulvar melanoma were slightly older with a median age of 68 compared to a median age of 66 among patients with squamous cell carcinoma (p<0.001). Vulvar melanoma had a higher rate of distant metastatic disease compared to squamous cell carcinoma, 7.3% versus 3.2%, respectively (p<0.001). On multivariable Cox regression including all patients, melanoma was associated with worse OS (HR 1.47, 95% CI 1.37-1.58, p<0.001) as compared to squamous cell carcinoma. On multivariable Cox regression for patients with vulvar melanoma, advanced disease stage, increased age, increased comorbidity score, increased tumor size, and care at a non-academic center were independent predictors for decreased overall survival. Surgical management of the primary site, lymphadenectomy, and private insurance provided a significant survival benefit. Radiation was associated with a survival decrement. The use of immunotherapy for vulvar melanoma has increased over time: 21.1% of patients received immunotherapy from 2004-2007, 27.4% of patients received immunotherapy from 2008-2011, and 51.6% of patients received immunotherapy from 2012-2015 (p=0.013). On univariable analysis, there was a trend towards improved survival with immunotherapy in patients with distant metastatic disease (HR 0.48, 95% CI 0.22- 1.03, p=0.06). For patients with vulvar melanoma, 5-year OS for localized, regional, and distant disease was 55.8%, 22.2%, and 5.1%, respectively.

Conclusion: Vulvar melanoma has a poor prognosis especially for those with regional and distant metastatic disease. Prognostic factors include disease stage, tumor size, patient age and comorbidities. Surgical management of both the primary site and regional lymph nodes provides a survival advantage. The survival decrement associated with radiation may be due to selection bias involving patients with inoperable disease or adverse features. The use of immunotherapy for vulvar melanoma has increased over time however its survival benefit may be limited to the setting of advanced disease. Further investigation is needed to improve outcomes for this rare disease.

Author Disclosure: A.A. Albert: None. R.M. Allbright: None.

Ashley Albert, MD

University of Mississippi Medical Center

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