Infection with certain types of human papillomavirus (HPV) appears to increase the risk of squamous cell carcinoma of the skin but not basal cell carcinoma of the skin. These results were published in the Journal of the National Cancer Institute.
Each year, more than one million people are diagnosed with skin cancer in the US alone. Melanoma is the most aggressive type of skin cancer, but is much less common than non-melanoma skin cancer.
The two most common types of non-melanoma skin cancer are basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). Sun exposure is thought to be the most important risk factor for both types of cancer.
Human papillomaviruses consist of a group of more than 100 different viruses. Some types of HPV cause warts on the hands or feet, other types cause genital warts, and some types have been linked with cancer, most notably cervical cancer. Researchers have speculated that there could be a link between certain types of HPV and non-melanoma skin cancer, but evidence for a link is limited.
To evaluate the link between non-melanoma skin cancer and HPV, researchers collected information from 252 patients with SCC, 525 patients with BCC, and 461 comparison subjects without skin cancer. Patients were diagnosed between 1993 and 1995 and were between the ages of 25 and 74. All subjects were tested for antibodies against 16 different types of HPV. Patients with antibodies against a specific type of HPV are considered seropositive (blood serum tests positive) for that type of HPV.
Results suggest a link between certain types of HPV and SCC:
- Individuals who were seropositive for any HPV type had an increased risk of SCC, but not of BCC.
- The overall risk of SCC was slightly higher among individuals who were seropositive for multiple types of HPV.
- When considering different subgroups of HPV, the subgroup known as beta HPV was the one linked with SCC. This subgroup includes HPV types 5,8,9,15,20,24,36, and 38.
- When individual types of beta HPV were analyzed separately, HPV 5 was the only one significantly linked with SCC. Compared to subjects who were seronegative for all beta HPVs, subjects who were seropositive for HPV 5 had an 80% increased risk of SCC.
- There was no link between any of the beta HPV types and BCC.
The researchers conclude that although sun exposure and sun sensitivity are the major risk factors for SCC, infection with certain types of HPV may also play a role.
Reference: Karagas MR, Nelson HH, Sehr P et al. Human Papillomavirus Infection and Incidence of Squamous Cell and Basal Cell Carcinomas of the Skin. Journal of the National Cancer Institute. 2006;98:389-95.