Certain types of papillomavirus might actually prevent cervical cancer, according to a new study. More than 100 different types of human papillomavirus (HPV) are known, and approximately 14 “high-risk” HPV types are known to cause cervical cancer.
The different types of HPV found in cervical smears and invasive cervical cancers from HIV-positive and HIV-negative women in Kenya were examined by researchers from The University of Manchester in the United Kingdom. The HIV-positive women had high numbers of a specific type of HPV (type 53) in normal cervical smears, but this was rarely found in HIV-negative women. This subtype was also never found in cervical cancers from either HIV-positive or HIV-negative women.
“It is well known that HIV increases the number of different types of HPV found in any one patient, which implies that HIV opens the door for infection with multiple types of HPV. If only high-risk types are present, these will undoubtedly accelerate progression to cancer, whereas if other types (eg, type 53) are also present, they may actually compete with the high-risk types to inhibit progression to cervical cancer,” said senior author Ian Hampson, PhD, senior lecturer in viral oncology at The University of Manchester.
There are 270,000 deaths from cervical cancer globally each year, and 85% of these occur in countries with low resources. Cervical cancer is the most common malignancy in Kenya, where it accounts for 18% to 23% of all diagnosed cases of cancer.
Hampson said the study suggested one possible explanation for why, in spite of a large increase in the numbers of HPV infections in HIV-positive African women, there was not a corresponding increase in numbers of cases of cervical cancer. This could also explain why another African study had actually shown the risk of developing one specific type of cervical cancer actually dropped in HIV-positive women, he said. This study’s results were published in the Open Virology Journal (2013; doi:10.2174/1874357901307010019).
The researchers now plan to do more research in this area. “Our study was quite small, and more research with larger sample numbers is now needed,” Hampson said. “We also need to work out exactly how one type of HPV might suppress the cancer causing properties of another. If it can be proved that HPV type 53 can inhibit the cancer-causing properties of other high-risk types of HPV, this could potentially form the basis of a simple biological therapy to prevent this disease. This could be extremely useful in low resource countries who cannot afford expensive HPV vaccines.”