HPV stands for human papillomavirus
Oropharyngeal cancer is cancer which develops in the tissue of the oropharynx, the middle part of the throat, including the base of the tongue, tonsils, the soft palate, and the walls of the pharynx.
According to prior studies, oropharyngeal cancers can be divided into:
- HPV-negative cancers - which are usually linked to alcohol and tobacco use
- HPV-positive cancers - which are associated with some types of HPV, a sexually transmitted virus. Those with this type of oropharyngeal cancer are usually younger than HPV-negative cancer patients.
Said senior author Maura Gillison, MD, PhD, professor of medicine and Jeg Coughlin Chair of Cancer Research at The Ohio State University Comprehensive Cancer Center in Columbus, wrote:
"We used to think of oropharyngeal cancer as one cancer, and now we know the disease is comprised of two biologically and epidemiologically distinct cancers. This new understanding will increasingly enable us to improve and better personalize care for patients with each form of the disease."
The team had previously demonstrated that survival rates and incidence for oropharyngeal cancers rose considerably in America between 1973 and 2004, while incidence rates for other cancers of the head and neck, such as oral cavity, dropped during the same period.
They tested 271 archived oropharynx cancer tissue samples from 5,755 patients for HPV infections. The samples came from three registries in Los Angeles, Iowa and Hawaii that had been collected between 1984 and 2004.
Using several molecular assays they demonstrated that the percentage of oropharyngeal cancers that were HPV-positive rose considerably during that period, from 16.3% between 1984 and 1989 to 72.7% between 200 and 2004.
In 1988, there were 0.8 cases of HPV-positive cancers per 100,000 people, compared to 2.6 in 2004 - a 225% increase. As smoking rates during the same period had dropped, HPV-negative oropharyngeal cancer rates dropped by 50%.
By 2020, HPV-positive oropharyngeal cancers will be the major form of cancer for the head and neck, and the leading HPV-linked cancer, overtaking cervical cancer if current trends continue, the authors added.
"These increases may reflect increases in sexual behavior, including increases in oral sex."
Gillison explained that between 90% and 95% of HPV-positive oropharyngeal cancers are caused by the same HPV type which is currently targeted by the vaccines administered to prevent cervical cancer - HPV 16.
"But with HPV vaccines, we have a great opportunity to potentially prevent oropharynx cancers in future generations - including in boys and men - but studies need to be done to evaluate the efficacy of HPV vaccines in preventing oral HPV infections."First author Anil Chaturvedi, PhD, said:
"Prospective studies are needed to investigate the natural history of oral HPV infection because little is currently known about its incidence and persistence, any modifiable risk factors involved in its persistence and opportunities for screening."
Gregory Masters, MD, American Society of Clinical Oncology (ASCO), Cancer Communications Committee member and head and neck cancer specialist, wrote:
"This is a significant study because it clarifies the growing role of HPV as a causative agent in head and neck cancer. The findings could have particular relevance for HPV vaccine administration policy and recommendations for those at risk for HPV-related cancers. We now have stronger evidence to tie behaviors to the incidence of different variations on this one cancer type.
What is interesting is that these findings about the incidence of oral cancer are in line with the simultaneous changes in sexual behavior patterns and the decline in smoking. We are encouraged by what the availability of HPV vaccines may be able to do to prevent these cancers now that we have a clearer understanding of causation, but we also have more work to do for those cancers unrelated to HPV."