Is this the end of the cervical smear test?

By Sophie Ramsey

BMJ Group News

What do we know already?

Cervical cancer kills nearly 1,000 women per year in the UK. Almost all cases are caused by HPV, which is passed through sexual contact. Although HPV infections often clear up on their own, they can sometimes damage cells in the cervix, which can lead to cancer.

The number of women dying from cervical cancer has dropped substantially in the last few decades as more women have had regular cervical screening with smear tests. In the UK, women aged between 25 and 64 years are eligible for smear tests every 3 to 5 years, depending on age. A sample of cells from their cervix is checked for changes that could become cancerous if not treated.

However, smear testing doesn’t detect all women at high risk of developing cervical cancer. More recently, researchers have looked at using HPV testing as a better way to identify women with a raised risk.

HPV tests check for genetic material (DNA) from the virus, to see whether a woman is infected with HPV strains that can cause cancer. Like a smear test, HPV tests are done on samples of cells collected from the cervix.

Studies show that HPV tests can detect more women with pre-cancers than smear tests, but many questions remain about how to most effectively use the test. For example, should it be used on its own, as the primary screening test, or combined with the smear test? Can looking separately at high-risk HPV strains (types 16 and 18) better illuminate a woman’s risk if she tests positive for the virus? Would repeat HPV testing be of value, to pinpoint women at higher risk due to prolonged infection?

Two new studies have looked for answers.

HPV testing, smear testing - or both?

This study included more than 47,000 women, aged 25 years and older, who had both smear and HPV testing.

Women who had abnormal smear tests were referred for a colposcopy (a close examination of the cervix). Women who had normal smears but tested positive for HPV also had a colposcopy, as did a random sample of women who had negative results on both tests.

Colposcopy identified 254 women with changes in their cervix, strongly suggesting advanced pre-cancer. Nearly all the women (92 percent) had tested positive for HPV, while only 53 percent had abnormal smear tests.

The researchers also found that combining HPV and smear tests detected only 4.7 percent more women at high risk, but led to one third more women with false-positive screening results.

When looking separately at women with positive HPV tests, the researchers found that those with HPV types 16, 18, or both had a particularly high risk of more advanced pre-cancer.