The background of the study started with looking at the association of human papilloma viruses and human cancers. The cancers that we really want to focus on are both screenable, unscreenable cancers and also cancers that are potentially preventable via vaccination. The concept of the study and the focus of our project was to look at how certain cancers that are screenable, such as cervical cancer, and cancers that are preventable, such as cervical cancer, oropharyngeal cancer and even vulvar and vaginal cancers and anal cancers, can potentially be prevented through vaccination with the human papilloma virus vaccine. We wanted to see since the introduction of the HPV vaccine in 2006 have we seen a decrease in the number of new cases of cervical cancer and other cancers that are associated with the human papilloma virus that would have seen a decrease in the incidence since the introduction of the vaccine on a population level.
In this study we used United States Cancer Statistics, a public use database. We used different joint point analysis and the SEER*Stat to calculate the annual incidence of these HPV associated cancers and also the annual percent change of these cancers, whether they’re increased or decreased, adjusted based on age, sex, race and specific cancer types.
One of the most important findings of our study that we noticed was that there was a significant decrease in the incidences or the number of new cases of cervical cancers in the United States. In particular we saw this decrease in young women which is suggestive of the continual benefit of cervical cancer screening and possibly due to the introduction of the human papilloma virus vaccination. However, we did see that there were increases in other HPV associated cancers where there is no standard screening in the United States. These include the anal rectal squamous cell cancers as well as oropharyngeal cancers, especially in men.
The impact of these results can clearly affect the future treatment, surveillance and also prevention of human papilloma virus related cancers. For example, prevention and early detection are clearly the best approaches. We need to increase the adherence to screening and also the adoption of the human papilloma virus vaccination for cervical cancer, particularly in the high risk groups. Also we notice that the screening by itself has seen a continuous decrease and the vaccination possibly significantly enhanced the decrease in the new cases of cervical cancer due to the introduction of the vaccination of human papilloma virus.
Another potential impact for future guidance is that the vaccination in the United States compared to other countries, such as Australia or Sweden, has not been as widely adopted throughout our communities in the United States. Better education and resources towards access to screening and vaccination to prevent human papilloma virus associated or related cancers are clearly important to continue the progress that we have already been able to demonstrate based on this current study.
But one of the things that I think is truly concerning and warrants further study is potentially developing better screening methodologies for anal rectal and also oropharyngeal cancers where we are beginning to see this increase in the incidence without a decline that we saw in cervical cancer. So future research in terms of prevention and early detection are needed for these other HPV associated cancers that are unscreenable or where we have not seen a decline since the introduction of the vaccination.
Although our study showed that the decrease in incidence in cervical cancer possibly is associated with the human papilloma virus vaccination given the timing of our study over the 17 year period that we were able to evaluate this and with the vaccination introduced in 2006 and our study spanned from 2001 to 2017, we were able to see the pre- and post-vaccination era to see potentially the association of how the HPV vaccination has potentially impacted in the incidence of cervical cancer. This is one of the first studies that has been able to show that, not just based on a clinical trial but on a population level in the United States. The only thing that is concerning and that clearly needs further investigation is why the men with oropharyngeal cancer, where 80% of human papilloma virus related cancers in men are associated with oropharyngeal cancer, why is there an increase in this population and how can we intervene so that these other HPV related cancers do not become a significant concern in our population based on cancer incidence and epidemiology.