HPV Viruses Linked to Skin Cancer
Non-Genital HPV Wart Viruses May Raise Risk of Common Skin Cancers
July 8, 2010 -- The HPV viruses that cause non-genital warts may increase the risk of getting common skin cancers, especially in people on long-term steroid medications.
The finding comes from a study comparing 1,561 people with the most common kinds of skin cancer -- squamous cell and basal cell carcinoma -- to people without cancer.
There are more than 100 types of human papillomavirus (HPV). The most well-known types are sexually transmitted and cause genital warts, cervical cancer, and anal/genital tumors. But other HPV types spread easily without sexual contact and are a leading cause of non-genital warts, especially on the arms and fingers.
Earlier studies have linked some of these HPVs to skin cancer, especially in transplant patients on immune-suppressing therapy and in people with a genetic disease (epidermodysplasia verruciformis) that suppresses immune responses.
Now Margaret R. Karagas, PhD, of Dartmouth Medical School, and colleagues have taken these studies a step further. They looked for antibodies to 16 different skin HPV types in both cancer cases and non-cancer cases.
"We didn't find any high-risk types of HPV, as is the case for anal/genital cancer. But what we did find is a relationship between squamous cell carcinoma and the number of types to which someone tests positive," Karagas tells WebMD.
People with squamous cell skin cancers tended to have been infected with more skin HPV types, or cutaneous HPV, than those who did not have cancer, Karagas and colleagues found.
Moreover, there was evidence that people on long-term steroid medications for chronic conditions such as rheumatoid arthritis and asthma were at higher risk of HPV-associated skin cancer. These drugs have a mild, immunity-suppressing effect.
HPV, Warts, and the Immune System
What's happening? University of Miami dermatology professor Robert Kirsner, MD, notes that cutaneous HPV usually is kept in check by the immune system.
"Many people are exposed to cutaneous HPVs. Some develop warts," Kirsner tells WebMD. "But most people after a while -- and we don't know exactly what 'a while' means -- develop immunity against them. That's why warts are more common in children than in adults."