Trends in HPV-dependent and HPV-independent vulvar cancers: The changing face of vulvar squamous cell carcinoma

Abstract

Objective: To investigate the incidence and survival of Vulvar Squamous Cell Carcinoma (VSCC) by etiology over a 27 year period.

Method: Retrospective case-note and pathology slide review of 390 consecutive VSCC, treated at a Centralized Cancer Centre covering half New Zealand's population, 1990-2016. Incidence was calculated in 5-6 year cohorts and correlated with precursor of the VSCC, age and stage.

Results: Age-standardized incidence of all VSCC did not change significantly, however age standardized incidence of HPV-dependent VSCC increased significantly, from 0.55/100,000 (95% CI 0.38-0.72) in 1991-2000 to 0.83/100,000 (95% CI 0.68-0.97) in 2001-2016, with a significant decrease in the incidence of HPV-independent VSCC, from 0.76/100,000 (95% CI 0.58-0.95) to 0.54/100,000 (95%CI 0.43-0.65). HPV-dependent VSCC in women ≥50 years increased significantly from 0.75/100,000 (95% CI 0.45-1.17) to 1.43/100,000 (95% CI 1.14-1.77), with no significant change seen in younger women. HPV-independent VSCC in women ≥50 years has decreased significantly from 2.53/100,000 (95% CI 1.95-3.23) to 1.62/100,000 (95% CI 1.31-1.98) with no change in younger women. The proportion of HPV-dependent VSCC has increased from 25% to 50%. Age standardized death rate from VSCC has not changed significantly from 0.22/100,000 (95% CI 0.10-0.34) in 2001-5 to 0.27/100,000 (95% CI 0.15-0.40) in 2011-16. Five year survival for HPV-dependent VSCC was 93% and 68% for HPV-independent VSCC (p < .0001).

Conclusions: HPV-dependent VSCC incidence has increased significantly and now accounts for half of VSCC, with a significant rise in women over 50. HPV-dependent and independent VSCC have different prognoses and should be registered and investigated separately.