A Pap test is a highly effective way to screen for cervical cancer. A small sample of cervical cells are examined, and if abnormal cells are found, they can be removed before they ever become cancerous. The Pap test has been enormously successful in reducing the rate of cervical cancer in Canada, but an estimated 1,550 women in the country will still be diagnosed with the disease this year.
As we learn more about the connection between the human papillomavirus (HPV) and cervical cancer, and as researchers develop new and better ways to test for the virus, a new screening possibility for cervical cancer is emerging. Rather than use a Pap test, it may actually be better to screen women for the presence of HPV, especially for strains HPV16 and HPV18, which cause 70% of cervical cancer cases.
Researchers in Australia recently reported results of a clinical trial that compared cervical screening through a traditional Pap test to screening with HPV testing, and their results support that HPV testing is an effective screening tool.
HPV test a reliable way to screen for cervical cancer
About 5,000 women participated in the study, and they received either a Pap test or HPV test. Women who had the Pap test and received a “high risk” result underwent further testing with a procedure called a colposcopy, which is a closer examination of the tissues for abnormal cells.
Women who had the HPV test were screened for whether HPV was present and which strain they had. Women who had either HPV16 or HPV18 were immediately referred for further testing with a colposcopy. When other strains were present, the women underwent follow-up, but not necessarily a colposcopy.
The researchers found that the HPV test identified more women with abnormal cells at high risk of becoming cancerous, compared to women who received a Pap test. These results suggested that HPV testing, and focusing on the high-risk strains, was a better screening test than the traditional Pap test.
HPV vaccine will reduce cervical cancer rates
Australia was one of the first countries to introduce HPV vaccination, and many of the women in the study had been offered the HPV vaccine. These results show that even in a vaccinated population, HPV testing is an effective screening tool.
The researchers in this study actually noted that both the Pap test and HPV test groups had low rates of abnormal cervical cells, and while they can’t definitively say why at this point, they suggest that it may be due to the impact of HPV vaccination. They plan to do further study to confirm whether this is the case.
All provinces in Canada now have school-based HPV vaccination programs, and we hope to see a further reduction in cervical cancer rates in the coming years because of vaccination. At this point, though, many women are still unvaccinated and screening is still a critical tool for cervical cancer prevention. A more effective screening test could help save lives.
Eileen Hoftyzer, BSc, and Carolyn Goard, PhD