Vulvar cancer is a rare malignancy. Its occurrence in Japan is 1/6-1/10 of that in the Western countries. Population-based statisics for vulvar cancer has been missing in Japan. To examine trends in clinico-pathological characteristics of vulvar cancer in Japan.
This is a nationwide retrospective study examining consecutive cases of women with invasive vulvar cancer in Japan between 2001-2010 (n = 1,061). Temporal trends of demographics, tumor characteristics, and survival outcome were assessed with cohort-level analysis. The National Cancer Institute’s Surveillance, Epidemiology, and End Result Program served as the external validation (n = 10,154).
The number of oldest-old women aged ≥80 years significantly increased from 18.0% to 30.6% (70.5% relative increase) over time. There was a stage-shift observed, and stage I disease decreased from 43.0% to 34.0% (21.0% relative decrease) whereas tumors with inguino-femoral nodal or distant metastasis increased from 23.2% to 35.6% (53.3% relative increase) during the study period (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 5-year survival rates significantly decreased between 2001-2010 (P < 0.05): 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 independently associated with decreased survival (all, P < 0.05). In the US cohort, the number of oldest-old women (25.2% to 27.8%) and the 5-year cause-specific survival rate (81.8% to 79.9%) stayed unchanged during the study period (all, P > 0.05).
Demographics and outcomes of vulvar cancer in Japan have significantly changed during the study period: Increasing oldest-old population and stage-shift to more metastatic disease resulted in cohort-level decrease in survival rates.
The authors.
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All authors have declared no conflicts of interest.