Last reviewed, May 2008

Next review, May 2009

Since 1993 cervical cancer has been classified as an AIDS-defining illness. At the time this was quite controversial as some doctors argued that HIV-positive women were no more likely to develop cervical cancer than HIV-negative women.

However, since effective anti-HIV treatment became available, it has become clear that there is a small increase in the risk of cervical cancer developing in HIV-positive women.

It is worth emphasising that the reason for the small increase in the number of cases of cervical cancer in HIV-positive women since effective became available is likely to be that women with HIV are living longer. Anti-HIV drugs do not cause cervical cancer.

Risk factors for cervical cancer

Human papilloma virus (HPV), the cause of genital and anal warts, is the underlying cause of cervical cancer. Infection with HPV is quite widespread amongst women with HIV. There are many different strains of HPV and only a few of these appear to cause cancer. The strains of HPV which cause visible, cauliflower-like warts on the genitals are not associated with cervical cancer.

In most cases, the body is able to clear infection with HPV, even those strains that cause cancer. However, HIV-positive women, particularly if they have a weak immune system, are less likely to be able to clear HPV infection naturally. Nevertheless, it is worth noting that even if high risk strains of HPV persist, they usually do not cause cancer.

Women who became sexually active at a very young age or who have had many sexual partners have a higher risk of being infected with high risk strains of HPV.

There is also some evidence that smoking increases the risk of cervical cancer if you are infected with high risk strains of HPV.

Cell changes

Before cervical cancer develops, cells in the cervix go through a number of changes over many years. These pre-cancerous lesions are often called CIN (cervical intraepithelial neoplasia). They are graded according to their stage – CIN I, CIN II, and CIN III.

Screening

Cervical smear tests (often called Pap smears) can detect precancerous changes to cells in the cervix before cancer develops. The test involves scraping cells from the lining of the cervix. These cells are then examined under a microscope. All women between the ages of 20 – 64 are recommended to have regular Pap smears.

HIV-positive women should have Pap smears more frequently than HIV-negative women. HIV-positive women should have a cervical smear when they are first diagnosed with HIV, six months after this, and then every year.

The cervix can be examined in more detail during a procedure by using a magnifying instrument called a colposcopy. At the same time small samples of tissue can be removed and examined under a microscope to see if precancerous changes in the cells have occurred.

Symptoms of changes to cells in the cervix include bleeding after sex, bleeding between periods and an unusual discharge from the vagina. However, these symptoms usually do not appear until there are precancerous changes, or even until the cancer is well developed, so regular cervical screening is strongly recommended.

Anti-HIV drugs and precancerous cells/cervical cancer

Often the immune system successfully clears infection with HPV. HIV therapy does not have a direct effect against HPV. However HIV treatment does improve the ability of the immune system to fight infections, including HPV.

Treatment for precancerous cells/cervical cancer

The earlier the treatment is provided the better, and if caught early the treatment of precancerous changes in the cervix can be highly successful.

Precancerous lesions can be treated with topical creams such as imiquimod, which is effective against both the visible warts and lesions and underlying HPV infection.

Other treatment options for warts and early precancerous lesions include freezing with liquid nitrogen and removal with a laser.

Warts and early precancerous lesions can be removed during a simple surgical procedure.

If the lesions are more advanced or cancer develops it is likely that surgery will be combined with a local radiotherapy and chemotherapy. There is some evidence that women who take HIV treatment after treatment for precancerous cervical changes or cervical cancer and have an undetectable viral load are less likely to develop a recurrence of the condition.

Vaccine

A vaccine has recently been approved that provides some protection against the strains of HPV that are associated with the highest risk of cervical cancer and another is in the final stages of development. NHS guidance suggests that it should be provided to girls before they are sexually active. Studies are underway to see how safe and effective one of the vaccines is in women with HIV.