Grant: Project Grant

In Canada, screening has helped to reduce the number of cervical cancer cases. However, there were still 1350 women diagnosed with cancer and 410 deaths in 2019. Persistent infections of high-risk HPV types can lead to the development of precancerous lesions that may slowly transform into cervical cancer. Because cervical cancer usually takes several decades to develop, there is time to identify precancers by screening and thus prevent cancer. Vaccination against high-risk HPVs, especially if done through school programs, can lead to more effective and equitable prevention, with less adverse effects. Our research team will evaluate the effectiveness of HPV vaccination against cervical pre-cancers and cancers, to determine if vaccine effectiveness is as good "in real life" as what was found in initial studies. Some studies have attempted to answer this question, with very mixed results, partly because the methods used led to some errors in the estimation of effectiveness in "real life". Between 2020 and 2023 we will contact women aged between 21 and 32 who will receive a diagnosis of cervical precancer or cancer. With their agreement, we will determine which HPV types are present in the lesions. This information will enable us to calculate the effectiveness of HPV vaccination. We will also check whether the effectiveness varies according to the age at vaccination, the number of doses of vaccine received, whether vaccination was started before or after the beginning of sexual activity and by the severity of the lesions. Vaccination against HPV offers the possibility to improve the prevention of cervical precancers and cancers, while using resources efficiently and few adverse effects. The demonstration, in Canada, of a high effectiveness of vaccination "in real life" could foster greater acceptance of vaccination and help plan future screening activities.