Time trends in human papillomavirus prevalence and genotype distribution in vulvar carcinoma in Norway.

INTRODUCTION: Approximately 25%-43% of all vulvar carcinomas are associated with human papillomavirus (HPV). In many countries, vulvar carcinoma incidence rates are increasing, possibly due to greater HPV exposure. However, studies exploring changes in HPV prevalence and genotype distribution in vulvar carcinoma over time are scarce. Our aim was to evaluate time trends in HPV prevalence and genotype distribution in vulvar squamous cell carcinoma in an unselected, nationwide sample of Norwegian women. Further, we explored clinical and histopathological aspects in relation to HPV status and investigated whether HPV status was associated with survival. MATERIAL AND METHODS: All vulvar squamous cell carcinoma cases from 1970-1975 and 2000-2005 were extracted from the Cancer Registry of Norway and corresponding tissue blocks were retrieved. After detailed histology review, HPV testing was conducted using real-time TaqMan PCR. Overall survival rates were calculated using the Kaplan-Meier method. Multivariable Cox regression analysis was performed to estimate hazard ratios adjusted for age at diagnosis, stage and diagnostic period. RESULTS: Histological review was performed on 352 vulvar squamous cell carcinoma cases. We were able to obtain valid HPV analysis results for 282 cases, Overall, 29.8% (95% CI 24.5%-35.5%) of cases were high-risk HPV (hrHPV)-positive. When comparing the two periods, we found that the percentage of hrHPV-positive tumors increased significantly from 23% (95% CI 16.0%-31.4%) in 1970-1975 to 35.3% (95% CI 27.8%-43.3%) in 2000-2005 (P = 0.025). The predominant genotypes were HPV 16 (73%), HPV 33 (21%), and HPV 18 (6%), with similar distributions in both periods. In the more recent cohort, several additional genotypes were detected: HPV 6, 11, 39, 45, 52, 58 and 66 were found in smaller percentages, ranging from 1.8% to 3.6%. In univariate analysis, patients with HPV-positive tumors showed improved overall survival compared with patients with HPV-negative tumors (hazard ratio [HR] 0.65, 95% CI 0.48-0.86). CONCLUSIONS: The prevalence of HPV in vulvar squamous cell carcinomas in Norway was significantly higher in 2000-2005 than in 1970-1975. The three predominant genotypes were HPV 16, 33 and 18 in both time periods. However, several other HPV genotypes have emerged over the last decades. HPV-positivity was associated with better overall survival.

Vulvar carcinoma in Norway: A 50-year perspective on trends in incidence, treatment and survival.

OBJECTIVE: To explore trends in vulvar squamous cell carcinoma (SCC) incidence, age and stage at diagnosis, treatment and survival in Norway from 1961 to 2010. METHODS: From 1961 to 2010, 2233 cases of vulvar SCC were extracted from the Cancer Registry of Norway. Data on age at diagnosis, tumor morphology, stage of the disease and treatment were analyzed. Age-standardized incidence rates, adjusted to the Norwegian standard population, were computed. Relative survival was calculated as a ratio of the observed survival in the study population over the expected survival in the background population. Multivariate Cox model was fitted to estimate hazard ratios. RESULTS: The overall incidence of vulvar SCC increased >2.5 fold (from 1.70 to 4.66 per 100,000 women/year; P<0.01). Age-specific incidence rates increased among women aged ≤60years (by 150% in age group 0-39years, 175% in age group 40-49years and 68% in age group 50-59years). From 1971 to 2010, the percentage of patients receiving surgery as only treatment decreased from 81% to 61%, whereas the use of radiation and combination therapy (surgery and radiation) increased from 3% to 11% and 6% to 20%, respectively. 5-year relative survival increased significantly among women ≤80years (from 72% to 83% among women aged ≤60years and from 60% to 65% among women aged 61-80years). CONCLUSIONS: The incidence of vulvar SCC has increased since the sixties, particularly among women younger than 60years. Despite less aggressive surgical treatment, survival has improved.