In 2007, the International Agency for Research on Cancer affirmed that there was sufficient evidence to conclude that the human papilloma virus (HPV) is a cause of head and neck cancer (HNC). Of the estimated 12.7 million new cancers occurring in 2008 worldwide, 4.8 percent were attributable to HPV infection.
HPV is a common sexually transmitted infection (STI). Infection with low-risk types such as HPV-6 and HPV-11 may cause anogenital or oral warts, while infection with high-risk types such as HPV-16 and HPV-18 may cause cancers of the cervix uteri, penis, vulva, vagina, anus and oropharynx (including base of the tongue and tonsils). HPV is found in about 70 percent of the cancers of the oropharynx, but is rarely identified in HNC developed at sites other than oropharynx (such as oral cavity, larynx, hypopharynx, etc.). HNC of the oropharynx (OPC) is predicted to become the most common HPV positive cancer, surpassing cervical cancer by 2020. In 2017, out of 33,000 HPV-associated cancers in the U.S., it is estimated that 16,000 will be OPC.
In recent years, we have gained remarkable knowledge about the differences in HPV-positive versus HPV-negative HNC which is contouring more and more as two different entities. HPV positive cancer affects preferentially younger white male patients of higher socio-economic status. Oral sex is the main risk factor for this type of cancer and marijuana use is considered a co-factor. Similarly, tobacco use is the main risk factor for HPV negative HNC and alcohol use is considered the main co-factor. Men are affected three times more frequently than women in both types of cancer. Studies show that HPV-positive HNC patients have half the risk of death of HPV-negative HNC patients, regardless of treatment type. Patients with HPV-positive cancers are younger, healthier, and far more likely to be survivors faced with the long-term consequences of treatment. The delicate balance of cure and toxicity is of paramount importance in the treatment of HNC, as better prognosis and response to treatment adds a new dimension. Significant clinical research efforts are underway to de-intensify the treatment for HPV-positive HNC patients. Learn more about different clinical research efforts related to HPV, including how it may lead to head and neck cancer by clicking here.
Smoking among HPV-positive patients negatively impacts the prognosis. Public health efforts have reduced the smoking rate of any tobacco product in the United States from 40 percent in 1965 to 20 percent currently, and the decrease in the smoking rate seems to have resulted in a similar decrease in the incidence of smoking-related cancers of the oral cavity, larynx, and hypopharynx. It was expected that OPC would follow the same pattern. However, while the incidence of HPV-negative OPC decreased, the incidence of HPV-positive OPC increased by 225 percent between 1988 and 2009. The Centers for Disease Control and Prevention (CDC) note that OPCs are one of only five cancer types that increased in incidence from 1975 to 2009. The slope of growth has only become more significant in recent years, and it is predicted that the incidence will continue to increase in the U.S. over the next 30 years. Due to these increases, many, including the CDC, call the issue an epidemic.
Strong evidence supports the role of the HPV vaccine in girls in the prevention of genital HPV infection and decreasing the incidence of cervical cancer. In contrast, little is known about vaccine efficacy against oral HPV infection. Therefore, vaccination cannot at present be firmly recommended for the primary prevention of OPC. Regardless, the identification of a significant cause for this cancer provides a rare and perhaps extraordinary opportunity for the development of public health interventions. Prophylactic HPV vaccination holds considerable promise in reversing the increasing incidence trend of OPC after 2060. The causal link between HPV and HNC has led to a paradigm shift in our understanding of HNC risk, with important implications for global cancer prevention.
