Oral cancers are exploding in US. They could exceed cervical cancer in the next decade, new study shows.
Using samples collected from registries in three states, Ohio State University researchers showed that the proportion of oropharyngeal cancers increased significantly over time, from a little more than 16 percent during the 1980s to more than 70 percent in the 2000s. Also the problem was more discernible among men who tested positive for human papillomavirus (HPV).
If current trends continue, the study suggests HPV-related oropharyngeal will become the major form of head and neck cancer and the leading HPV-associated cancer, surpassing cervical cancer, by 2020.
"These increases may reflect increases in sexual behavior, including increases in oral sex," 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.
The oropharynx is the middle part of the throat behind the mouth, and includes the base of the tongue, the soft palate, the side and back walls of the throat and the tonsils. Oropharyngeal cancer is the second virus-related head and neck cancer known, with the other being nasopharyngeal cancer (Epstein-Barr virus).
Previous studies have shown that oropharyngeal cancers can be divided into two separate diseases with distinct causes: HPV-negative cancers, which are associated with tobacco and alcohol use; and HPV-positive cancers, which are linked to certain types of HPV, a sexually transmitted virus. Patients with HPV-positive oropharyngeal cancer also tend to be younger than those who are HPV-negative. Clinically, patients with HPV-positive cancer tend to have better survival compared to those with HPV-negative disease.
"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 researchers said.
Gillison and her team previously showed that incidence and survival rates for oropharyngeal cancers significantly increased in the U.S. from 1973 to 2004, whereas the incidence rates for other head and neck cancers, such as oral cavity cancers, declined during that period.
To determine the role of HPV infection in these trends, researchers tested 271 archived oropharynx cancer tissue samples (from 5,755 patients) for HPV infection collected between 1984 and 2004 at three population-based cancer registries located in Hawaii, Iowa and Los Angeles in the National Cancer Institute's Surveillance, Epidemiology and End Results (SEER) Residual Tissue Repositories Program. Using a variety of molecular assays, the investigators showed that the proportion of oropharynx cancers that were HPV-positive dramatically increased over time, from 16.3 percent for cancers diagnosed during the 1980s (1984 to 1989) to 72.7 percent for cancers diagnosed during the 2000s (2000 to 2004).
On a population level, they discovered that over just 16 years (1988 to 2004), the incidence of HPV-positive cancers rose from 0.8 per 100,000 to 2.6 per 100,000 - an increase of 225 percent. HPV-negative oropharyngeal cancers declined by 50 percent during that same time, likely due to declines in smoking and tobacco use.
Gillison noted that approximately 90 percent to 95 percent of HPV-positive oropharynx cancers were caused by one HPV type - HPV16, which is targeted by currently available vaccines for cervical cancer prevention. "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."
The authors said that patients with HPV-positive disease generally have a better prognosis than those with HPV-negative disease, and that radiation - in addition to chemotherapy - has a particularly strong impact on long-term outcomes. By contrast, for HPV-negative patients, there have been few treatment advances in 20 years that have led to improved survival.
The findings are published in the Journal of Clinical Oncology.