Changes in the Clinicopathological Demographics of Vulvar Cancer in Japan: Increasing Oldest-Old, Stage Shifting, and Decreasing Cohort-Level Survival †

Abstract

Background: To examine trends in the clinicopathological characteristics of vulvar cancer in Japan. Methods: This is a nationwide retrospective study examining consecutive women with vulvar cancer between 2001 and 2010 in Japan (n = 1061). Temporal trends in demographics, tumor characteristics, and survival were assessed by cohort-level analysis. The National Cancer Institute’s Surveillance, Epidemiology, and End Result Program was used for external validation (n = 10,154). Results: The number of oldest-old women aged ≥80 years significantly increased (from 18.0% in 2001 to 30.6% in 2010; 70.5% relative increase) in the study period. A stage shift was observed, with stage I disease decreasing from 43.0% to 34.0% (21.0% relative decrease), and tumors with distant metastases increasing from 23.2% to 35.6% (53.3% relative increase, p < 0.05). The number of women who underwent surgical treatment decreased from 84.0% to 69.7% (17.0% relative decrease), whereas utilization of radiotherapy increased from 34.4% to 43.2% (25.7% relative increase) over time (p < 0.05). In the cohort-level analysis, the five-year survival rates significantly decreased from 2001 to 2010 (p < 0.05), specifically, 66.9% to 51.0% for progression-free survival (23.7% relative decrease), 79.5% to 67.9% for cause-specific survival (14.6% relative decrease), and 74.9% to 62.3% for overall survival (16.9% relative decrease). In the patient-level analysis, oldest-old women were less likely to undergo surgical treatment and were independently associated with decreased survival (p < 0.05). In the US cohort, the number of oldest-old women (25.2% to 27.8%) and the five-year cause-specific survival rate (81.8% to 79.9%) remained unchanged during the study period (p > 0.05). Conclusion: Demographics and outcomes of vulvar cancer in Japan significantly changed during the study period. An increasing oldest-old population and a stage shift to more metastatic disease resulted in a cohort-level decrease in survival rates.