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Some types of human papillomaviruses, or HPVs, may increase the risk of nonmelanoma skin cancers, a new study finds.
A review of blood sample records in Norway and Sweden shows that people infected with a certain group of HPVs that make their home in skin cells were 30 percent more likely to develop squamous cell carcinoma, a type of skin cancer, over a 30-year period than those not infected with this group of viruses.
The longer the time since the initial infection, the higher the risk of developing skin cancer.
Previous studies found a link between certain HPV types and squamous cell carcinoma, but it was not clear which comes first. If HPV was present before the cancer, it could have caused it, but it's also possible the cancer made patients more susceptible to HPV infection.
The new study identified HPV infection in patients before their cancer diagnosis, and so it more strongly suggests HPV played a role in the cancer development, the researchers say.
There are over 100 strains of HPV, some of which are sexually transmitted and infect the genital area, and some that infect the skin and can be picked up from touching surfaces. Sexually transmitted HPVs have been implicated in the development of cervical cancer, genital warts and anal cancer.
Because there is already a vaccine against some of these sexually transmitted HPVs, it would be very easy to make a vaccine against skin HPVs if it becomes clear they cause disease, said study researcher Dr. Joakim Dillner, professor of infectious disease epidemiology at the Karolinska Institutet in Sweden.
HPV and skin cancer
Squamous cell carcinoma is a type of skin cancer that is often cured when treated early. Untreated squamous cell carcinoma can spread to other parts of the body and cause serious complications, according to the Mayo Clinic. The most common cause is prolonged exposure to ultraviolet radiation, from either the sun or tanning beds, the clinic says.
Dillner and his colleagues examined records from 850,000 people in Sweden and Norway who had donated blood samples to a biorepository, usually multiple times, since 1973.
The researchers identified 2,623 people who had donated blood before they were found to have squamous cell carcinoma or basal cell carcinoma, another type of nonmelanoma skin cancer. Their blood samples were analyzed for presence of antibodies against 33 types of HPV and compared with samples from 2,623 blood donors who did not have skin cancer.
The presence of antibodies against HPV indicated a person had the infection at one time but did not say whether he or she was still infected.
Participants with antibodies against a particular group of HPVs that include HPV types 9, 15, 17, 23, and 38 were found to be at increased risk of developing squamous cell carcinoma later in life. If the antibodies had been present for more than 18 years, participants were 80 percent more likely to develop squamous cell carcinoma than those whose antibodies were present for a shorter period, Dillner said.
The results held regardless of participants' lifetime exposure to UV (ultraviolet) rays, which was estimated by using UV radiation data from where the participants lived. However, this information did not account for how long participants stayed outside or whether they used tanning salons.
While more research is needed to confirm the link, the finding suggests patients one day could be tested for certain types of HPV to see if they are at risk for skin cancer, said Dr. Michele Green, dermatologist at Lenox Hill Hospital in New York, who was not involved in the study.
Patients might be tested when they visit the dermatologist for warts, which are also caused by HPVs, Green said. If patients were found to have "high- risk" HPV types, they could be closely monitored for the development of cancer, Green said. "It will be important knowledge to be able to have," she said.
The study was published March 14 in the American Journal of Epidemiology.
Pass it on: Infection with certain HPVs of the skin may increase the risk for developing skin cancer.