A study by the Singapore General Hospital (SGH) has found that co-testing, which combines Pap smear and HPV (human papillomavirus) DNA test, significantly improves the detection rate of cervical cancer than either test alone.
Pap smear, which screens for the presence of precancerous and cancerous cells on the cervix, has helped cut prevalence of cervical cancer in the last 30 to 40 years. Mortality rates were further reduced with the introduction of a national Pap smear screening programme in 2004. But like any other screening tests, Pap smear is not 100 per cent accurate.
“Cervical cancer is highly preventable. Although Pap smear is the recommended screening tool to detect cancer, we wanted to see if there are better ways to further enhance detection rate given the rapid medical advances in the last decade,” said Professor Tay Sun Kuie, Senior Consultant, Department of Obstetrics and Gynaecology, SGH.
With growing evidence from studies, which showed that combining Pap smear and HPV DNA tests pushes detection rate up to 95 per cent, SGH introduced a cervical cancer co-testing programme in November 2013 for women above 25 years old.
The HPV DNA test is capable of detecting the presence of all 14 HPV strains known to cause cervical cancer and, separately the test is able to single out two most common and aggressive virus strains – HPV 16 and 18. These two strains account for about 70 per cent of cervical cancer cases. More importantly, the HPV DNA test is able to pick up more cases of pre-cancers and an aggressive type of cervical cancer, known as adenocarcinoma, much earlier.
To study the efficacy of co-testing, SGH analysed the results of 1,900 women who underwent co-testing between November 2013 and August 2014. The findings affirmed that adding HPV DNA test to the Pap smear test does increase sensitivity of pre-cancer detection as more of such cases, which could have been missed with just Pap smear alone, were picked up. The study was presented recently at the Asia-Oceania Research Organisation in Genital Infection and Neoplasia (AOGIN) Biennial Conference in August 2016.