Link between HPV and cervical cancer

Scientists in the United States have carried out a review of research to determine the link between persistent HPV (human papillomavirus) infection and cervical cancer.

The researchers from the University of North Carolina at Chapel Hill say their systematic review and meta-analysis found that persistent HPV infections could be an indication for a increased risk of cervical cancer.

Cervical cancer is the second most common cancer in women throughout the world and the first symptoms are usually vaginal bleeding but symptoms may not appear until the cancer has reached an advanced stage.

Treatment in the early stages usually involves surgery, and chemotherapy and radiotherapy in advanced stages of the disease.

Pap smear screening can identify potentially precancerous changes, and the use of this screening process has meant the rates of invasive cervical cancer have been reduced by 50% or more.

HPV is a sexually transmitted virus that can cause high-grade cervical lesions and these increase a woman's risk of developing invasive cervical cancer.

The current Pap smear tests widely used in screening programs detects changes in the cervix before a cancer develops.

The researchers say testing for HPV infections has the potential to provide a more sensitive indication for future cervical cancer and screening programs should use this as a clinical tool.

Their review looked at research carried out from January 30, 2006 which encompassed more than 22,500 women and looked at the association between persistent HPV DNA and invasive cervical cancer.

Lead researcher Dr. Jennifer Smith, says they found that a persistent HPV infection of six months to one year was consistently associated with a woman's increased risk of high-grade cervical lesions or cervical cancer.

The researchers say there are approximately 14 high-risk types of HPV that cause invasive cervical cancer - the two most common types are 16 and 18, which have different viral genetic patterns.

It is these particular virus types which are responsible for around 70 percent of invasive cervical cancer and 50 percent of high-grade lesions and the researchers say the next step will be to develop a consensus definition of HPV 'persistence' that can then usefully inform clinical practice for future cervical cancer screening programs.

They believe that measuring the persistence of HPV infections might identify potential cervical cancer cases that otherwise may be undetected.

In Australia as in other developed countries the rates of cervical cancer have dropped considerably since the introduction of the smear test.

In 2004 there were 718 new cases compared with 1090 in 1991, and the mortality rate has dropped by half to 1.9 deaths per 100,000 women.

Experts however have expressed concern that a new report from the Australian Institute of Health and Welfare, says that the take up by women under 40 fell by about 15%.

Nevertheless 61% of Australian women undergo cervical screening every two years, as officially recommended.

The study the "Persistent Human Papillomavirus Infection and Cervical Neoplasia" is published online in the American Journal of Epidemiology.