Changes In The Incidence Of HPV-Related Gynecologic Cancers In Canada: From 1971 To 2010 A Population Based Study

Joseph NIYIBIZI, University of Montreal, Canada

1 Department of Social and Preventive Medicine, Sainte Justine Hospital Research Center, Montreal, Quebec, Canada
2 Department of Obstetrics and Gynecology, Faculty of Medicine Memorial University, St John's, Newfoundland, Canada
3 Public Health Agency of Canada, Ottawa, Ontario, Canada
4 Merck Canada, Montreal, Quebec, Canada

Purpose: Assess the change in incidence of HPV-related vulvar, vaginal, and cervical cancer over 40 years and evaluate temporal and age specific trends.
Methods: National Incidence Data for HPV-related vulvar, vaginal and cervical cancers were obtained from the Canadian Cancer Registry for January 1st, 1971 to December 31st, 2010. Age standardized incidence rates (ASR) per 100,000 person-years were calculated. ASR trends were analyzed using the Joinpoint Regression Program. The Average Annual Percentage Change (AAPC) was used to summarize trend changes over this period, rejecting the null hypothesis that AAPC equals 0 if the resulting p-value was <0.05.
Results: Per 100,000 the ASR for cervical and vaginal cancers decreased from 24.7 to 9.8 and 1.3 to 0.7 from 1971 to 2010 respectively. Correspondingly the AAPC for cervical cancer was -2.3 (95% CI -3.2; -1.3) p=0.0 and for vaginal cancer -1.8 (95% CI -2.5; -1.1) p=0.0. For vulvar cancer the ASR remained unchanged: 2.9 and its AAPC did not change significantly over this period. Almost a quarter of cervical (23.4%), vaginal (24.6%) and vulvar cancers cases (25.3%) were diagnosed in 35-44, 65-74 and 75-84 years old respectively. Compared to the earliest and most recent cohorts, the 1970-1980 birth cohorts show the highest ASR.
Conclusions: Mainly with the uptake of cervical cancer screening in Canada, cervical and vaginal cancer incidence has decreased from 1971 to 2010. As vulvar cancer is not directly linked with a screening tool, there has been no change in incidence. With the uptake of HPV vaccination, further decrease in rates of all the HPV related gynecologic cancers is expected in the coming years.
Funding source: None