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HPV Linked to Squamous Cell Carcinoma
 
 
  By Michael Smith, North American Correspondent, MedPage Today Published: July 09, 2010
 
Action Points
 
* Explain to interested patients that basal cell and squamous cell carcinoma of the skin are increasing, and exposure to UV light is the main risk factor.
 
* But note that this study suggests that some forms of human papillomavirus may increase the risk of cutaneous squamous cell carcinoma.
 
Human papillomaviruses -- long associated with cancers of the genitalia and reproductive tract -- may also play a role in skin cancer, researchers said.
 
In a case-control study, people with squamous cell carcinoma were significantly more likely than controls to test positive for antibodies to one or more genus human papillomaviruses (HPV), according to Margaret Karagas, PhD, of Dartmouth Medical School in Lebanon, N.H., and colleagues.
 
The odds of having the disease increased with the number of different types of HPV found in a study participant's blood, Karagas and colleagues reported online in BMJ.
 
On the other hand, they wrote, there was no association with basal cell carcinoma.
 
Both basal cell and squamous cell carcinoma are increasing, with ultraviolet radiation as the main established risk factor, the researchers noted.
 
And previous research has shown links between skin cancers and genus HPVs particularly among people with epidermodysplasia verruciformis -- a genetic disorder characterized by defective cell mediated immunity, which leads to diffuse warty and malignant skin lesions.
 
A similar link has been seen among organ transplant recipients, Karagas and colleagues wrote, but there is limited evidence of a link in the general population.
 
To help fill the gap, they analyzed the occurrence of HPV antibodies in 2,366 people ages 25 to 74, including 663 with squamous cell carcinoma, 898 with basal cell carcinoma, and 805 healthy controls matched for age and sex.
 
The volunteers were interviewed and their blood was tested for antibodies to 16 genus HPVs.
 
Analysis showed:
 
* Positivity to at least one é HPV type was associated with an overall odds ratio of 1.3 for squamous cell carcinoma (95% CI 1.04 to 1.61). On the other hand, it was 0.97 for basal cell carcinoma (95% CI 0.80 to 1.19).
 
* The odds ratio for squamous cell carcinoma rose with increasing numbers of é HPVs types found, from 0.99 for one to 1.71 for more than eight. The categorical trend was significant at P<0.001 and the continuous trend was significant at P=0.003.
 
* The odds ratio for squamous cell carcinoma was 1.59 (95% CI 1.03 to 2.44) among cases with histological evidence of actinic keratoses, compared with 1.37 (95% CI 0.94 to 2.02) among those without such evidence.
 
* There was also increased risk for people with a sun-sensitive skin type, but no apparent link with history of sunburn.
 
The study had a large number of volunteers, Karagas and colleagues noted, and the population-based design renders it less susceptible to selection bias than other forms of investigation. All the same, they acknowledged, residual confounding can't be ruled out.
 
And, they noted, the study population was American and almost exclusively white, so that the applicability of the findings to other populations is not certain.
 
However, the finding of increasing risk associated with increasing numbers of HPV types "supports a possible causative role of genus é human papillomaviruses in squamous cell carcinoma," they argued.
 
The study had support from the NIH, the National Cancer Institute, and the European Community.
 
The researchers said they had no conflicts.
 
Primary source: BMJ
Source reference:
Karagas MR, et al "Genus é human papillomaviruses and incidence of basal cell and squamous cell carcinomas of skin: population based case-control study" BMJ 2010; 341: c2986.
 
 
 
 
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