The researchers investigated whether introduction of HPV-testing for women with minor / abnormal cell changes has increased the efficiency of detecting clinically relevant high grade lesions and in this way improved the cervical cancer screening program.
- We rarely see such unambiguous and clear results when we evaluate governmental health policy measures. HPV testing of women with abnormal Pap smears is clearly effective, says Giske Ursin, the Director of the Cancer Registry of Norway.
- The combination of Pap smears and HPV testing improves detection of low risk and high risk precursors of cervical cancer, says Tor Haldorsen who is the researcher responsible for the report.
Secondary screening with HPV testing
By conducting HPV tests on women with abnormal Pap smears more women with a high risk of precancerous cell changes will be referred for further investigation. Statistics show that of all those who take a Pap smear, around 8 000 women per year will have abnormal results. Of these, around 1 000 women will develop severe precursors of cervical cancer before the next screening. It is precisely these cases with precursors of cervical cancer that can be detected by a reliable HPV test in secondary screening.
Differences in the quality of the HPV tests
Five different HPV tests have been used in Norway since 2005. The three most used are: Hybrid Capture II, Pre Tect HPV-Proofer and Amplicor.
Over 15 000 women had a HPV test taken as part of secondary screening. These were followed up to see how many developed severe cell changes. The report documents the extent to which the different HPV tests were able to detect severe precursors of cancer. Amplicor and Hybrid Capture II identified 97 and 93 per cent respectively. Pre Tect HPV-Proofer only detected 75 per cent.
- The report therefore concludes that we should be using the HPV tests which show better results than the Pre Tect HPV-Proofer in secondary screening of cervical cancer, says Haldorsen.
- This is no surprise, Ursin says and adds: This is consistent with results from international studies that have compared the qualities of the tests.
The advisory group for the Norwegian Cervical Cancer Screening Programme supports this evaluation and the conclusions in the report.