Invasive extramammary Paget's disease of the vulva: incidence, trends and outcomes

Abstract

<h3>Objectives:</h3> To explore the incidence, trends and survival outcomes of invasive extramammary vulvar Paget's disease compared to squamous and basal cell vulvar cancers. <h3>Methods:</h3> Incidence data were extrapolated from the United States Cancer Statistics (USCS) from 2001 to 2017 by SEER*Stat. Trends analysis was performed by Joinpoint regression program and presented by average annual percent change (AAPC). Clinical data on demographics, disease and treatment were recorded from the National Cancer Database from the same period. Chi-squared test, Kaplan-Meier survival estimates, and Cox proportional hazards model adjusted for covariates were used. <h3>Results:</h3> From 2001-2017, there were 3,715 cases of malignant extramammary Paget's disease of the vulva. Whites comprised 3,172 cases (85.4%), followed by Asian/Pacific Islanders with 227 cases (6.1%), Hispanics with 198 cases (5.3%), and Blacks with 44 cases (1.2%). Most cases had localized disease (73.1%), 10.4% had regional spread and 1.2% had distant disease. The overall incidence was 0.12/100,000 women per year in 2017. The incidence increased with an average percent increase of 0.4% per year from 2001 to 2017 (p<0.01). Of 1,388 patients with invasive vulvar Paget's disease from the NCDB, the median age was 72 (range: 63-80) years. Local excision was performed in 77.4% of cases, and 10.7% underwent radical surgery. The overall five-year survival was 85.9%. Older age (HR=7.95, p<0.001), advanced disease (HR=6.0, P<0.001), positive LVSI (HR=2.81, p<0.001), and Charlson comorbidity index ≥ 1 (HR 2.17, p<0.001) had worse survival. Using the NCDB, we compared the 5 year survival rates of vulvar squamous cell carcinoma (SCC) (n=28,587) and basal cell carcinoma (BCC) (n=1,720) to invasive Paget's disease. The survival of SCC and BCC were 63.5% and 77.9% compared to 85.9% for invasive Paget's disease. More specifically, the survival of early stage I and II were SCC: 73.7% and 59.3%, BCC: 79.5% and 60.5% and Paget's: 83.6% and 81.3%. Survival of advanced stage III and IV were SCC: 45.3% and 24.8%, BCC: 71.4% and 50.0% and Paget's: 52.5% and 41.7%. <h3>Conclusions:</h3> Invasive extramammary Paget's disease of the vulva is uncommon though the incidence is increasing. Older age and advanced stage are associated with poorer survival. Patients with metastatic vulvar Paget's disease and squamous cell carcinoma have a poorer survival compared to metastatic vulvar basal cell carcinoma.