Swedish researchers have found that the Human papillomavirus (HPV) that causes cervical cancer in women is also a risk factor for oropharyngeal squamous cell carcinoma (OSCC) or oral and throat cancer in men even if they do not smoke or consume alcohol.
The review of existing literature was conducted by Trobjorn Ramqvist and Tina Dalianis and published online October 13 in Emerging Infectious Diseases. Dr. Dalianis is professor of tumor virology and the head of the Department of Oncology–Pathology at Karolinska Institutet in Stockholm. They found that the main reason behind this rise was due to sexually transmitted HPV and other factors like multiple sex partners, starting sexual activity at a younger age, and increased oral sex.
They found that from 1970 to 2002, tonsillar cancer (which is the most common OSCC) increased in Stockholm, Sweden, by 2.8-fold, and by 2006/07, 93% of all tonsillar cancers in that city were HPV-positive. The most common OSCC is tonsillar cancer, followed by base of tongue cancer. 5 year survival for this type of cancer is only 25% but HPV positive cancer has better chances of longer survival.
Dr. Dalianis said, “we realized that there was an increase in HPV-induced tonsillar cancer, but we did not realize it was so eminent until we separated the 2 groups (HPV-negative and -positive tonsillar cancer cases) the way we did.” She informed that HPV (most commonly type 16) was found in 45% to 100% of OSCCs in various studies. “It was also observed that patients with HPV-positive OSCC were younger and lacked the traditional risk factors of smoking and alcohol consumption…We suggest the increased incidence of OSCC depends on HPV infection and results in an increased proportion of HPV-positive OSCCs,” the paper reads.
For the review the authors used data from the Swedish Cancer Registry.
There were critics to the review. Dr. Boudewijn J.M. Braakhuis from the section of tumor biology in the Department of Otolaryngology/Head and Neck Surgery at VU University Medical Center in Amsterdam, the Netherlands said that the proportion of HPV-positive OSCCs in the Amsterdam area is about 20%. He said that the Swedish study did not have a standardized method for measuring HPV involvement. Dr. Braakhuis's group proposes doing p16 staining followed by general primer polymerase chain reaction with typing, which might reduce the risk for false positives.
According to Dr. Dalianis HPV-positive tonsillar cancer was linked not only to oral or vaginal sex but also according to one of the studies, linked to “open-mouthed kissing.” Dr. Dalianis said that this has implications for the timing of vaccinating children to prevent HPV. She is “a strong supporter of giving the HPV vaccine to both girls and boys” and writes “it is crucial to monitor the effects of the present HPV vaccination, not only on the incidence of cervical cancer but also on the incidence of OSCC.” Dr. Braakhuis agreeing to this said, “One may expect that vaccination will decrease the number of HPV-positive oropharyngeal cancers.” The Food and Drug Administration (FDA) approved the use of Gardasil, the vaccine against HPV, for girls in 2006 and for boys for treatment of genital and anal warts in 2009.
The review covered another important area. It showed that the incidence of head and neck squamous cell carcinoma is decreasing and OSCC is increasing. The authors write, “It is possible that increasing numbers of OSCC patients with a better prognosis are being treated with intensified therapy. As a result, many patients have substantial chronic unnecessary side effects. It is therefore necessary to identify which patients need and which do not need intensified treatment.”