Trends in incidence and survival of patients with vulvar cancer in an Asian country: Analysis of the Korean Central Cancer Registry 1999–2018

Objective: To report 20-year trends in incidence and survival of vulvar cancer in Korea. Methods: Using data from the Korean Central Cancer Registry, age-standardized incidence rates (ASRs) and annual percentage changes (APCs) were calculated. Net survival (NS) was estimated by the Pohar-Perme method, and conditional net survival (CNS) was calculated. Results: A total of 2221 patients was diagnosed with vulvar cancer during the 1999–2018 period, with an ASR of 0.32 per 100,000 person-years. Among the cases, 51.4% were squamous cell carcinoma (SqCC), 21.3% were Paget disease, and 8.6% were basal cell carcinoma (BCC). There was an increase in incidence for all vulvar cancer (APC 2.4%, 95% CI 1.8–3.0). However, although BCC (APC 7.0%, 95% CI 3.3–10.8) and Paget disease (APC 5.9%, 95% CI 4.2–7.6) increased, SqCC did not (APC 0.2%, 95% CI -0.8–1.2). There was an increase in incidence in all age groups. The 5Y NS was 74.0% overall, and it did not improve significantly during the study period. The 5Y CNS of vulvar cancer increased continuously with time survived: from 74.0% (71.4–76.4) at baseline to 98.1% (95% CI, 85.4–99.8) at 5 years after diagnosis. Conclusions: The incidence of vulvar cancer in Korea showed a different pattern from those in the US and Europe: SqCC incidence was relatively low and remained stable, but the incidence of BCC and Paget's disease increased. Survival did not improve in the past two decades. Patients can be considered cured after surviving for 5 years.