Variations of HPV in head and neck across the world
Dr Gypsyamber D'Souza - Johns Hopkins University, Baltimore, USA
What were you discussing in this meeting?
We were interested in the role of HPV in head and neck cancer and how that varies across different countries in the world. So we compared three different countries, there was a study performed in Brazil, a collaboration of studies in Western Europe and then another study in North Carolina in the United States. We wanted to evaluate what differences there were within the role of HPV in head and neck cancer in these three regions.
How did you evaluate this?
We consolidated tumour samples and risk factor survey information and survival information from each of these studies into one place. We centrally tested for p16 and HPV16 DNA; those are two biomarkers of whether a tumour is HPV related or not. We centrally tested those tumours and we took our risk factor information and also made that risk factor information comparable across the three studies so that we could then evaluate the role of HPV.
What are the statistics?
We had around 500 cases from each of the three continents, so 1,500 cancers total and these were cancers diagnosed in the early 2000s to 2005.
What are the findings?
We found that there was tremendous variation in the role of HPV in oropharyngeal cancers. We know HPV has a strong role in oropharyngeal cancer in the West and indeed we saw that in the cases from the United States, it caused the majority of those oropharyngeal cancers. In Europe HPV appeared to cause around half of the oropharyngeal cancers and in Brazil there was a very small proportion, less than 10%, that were caused by HPV. So there was tremendous variation. We also explored the role of HPV in nano-oropharyngeal cancers and there we saw consistently across the three regions HPV had a minor role, causing less than 20% of oral cavity or laryngeal cancers in all three regions.
What could be the implications of this research?
We also looked at the role on survival and we saw within all three regions HPV was a strong predictor of better survival. Even after you adjusted for other risk factors such as age and tobacco, alcohol and stage, having an HPV related tumour had much better survival in all three regions. Now why there’s such discrepancy within different regions for the role of HPV needs to be better explored. Part of it is because there are a higher number of tobacco and alcohol related oropharyngeal cancers in Brazil and in Europe than in the United States and so even at the same rate of cancer it would be a smaller proportion that you see being HPV related. But it appears that there may also be some differences in the rates of cancer and these may be explained by differences in behaviour and HPV acquisition within these different regions.
Could this have implications for policy or future research?
One of the reasons that the role of HPV in oropharyngeal cancer is important is that these cancers are very distinct. They occur in people who are younger, who do not have as many of the traditional risk factors and it’s an emerging epidemic that we see with cancers rising for these HPV related oropharyngeal cancers; in many regions the incidence is increasing. Here in Brazil what we saw in our study was not a large number currently but we don’t know what that will look like in five, ten or fifteen years; as these trends continue within each region there’s a possibility that this will continue to be more of a problem.
