The Pap smear test has been used widely for the past five decades to understand and screen for early signs of cervical cancer. The conventional test has been largely replaced by a liquid-based Pap cytology test. Soon it may be replaced by another test – the Human papilloma virus test or the HPV test finds new research.
The Canadian researchers explain that almost all cases of cervical cancer are associated with a HPV infection. They checked on nearly 19,000 women and found that detecting HPV was more predictive of early stage cervical cancer than the routine Pap tests. They also found that the HPV test was a better predictor of women who would be cancer free in future compared to Pap test. They noted that women who had a negative HPV test were more likely to be cancer free for the next four years compared to those who got a negative Pap test.
Lead researcher Dr. Gina Ogilvie, a professor in the School of Population and Public Health at the University of British Columbia, in Vancouver explained that cervical cancer screening should be performed for all women who belong to the reproductive or childbearing age. She added that there have been thousands of women whose lives were saved because they were screened for cervical cancer and their cancers were detected early. However this new HPV test may soon replace the existing Pap test as a more preferred screening test, she said. She explained that at present the guidelines recommend that all women undergo both Pap test as well as HPV test.
According to American College of Obstetricians and Gynecologists (ACOG) women aged 21 to 29 years should have a Pap test every three years while women aged between 30 to 65 years should have a Pap test along with a HPV test every five years or a Pap test every three years. However the actual benefit lies with the HPV test she said. She explained that according to the new draft guideline from the U.S. Preventive Services Task Force, HPV test may soon replace the Pap test.
The Task force states that for women aged between 29 and 65 HPV tests alone every five years can be the only screening test. They could also get a Pap test every three years. For women under 25, the Task Force suggests use of Pap test alone because many of them are infected with HPV. Cervical cancer in women less than 25 is rare and a positive HPV test might mean unnecessary treatment Ogilvie explained.
This study titled “Effect of Screening With Primary Cervical HPV Testing vs Cytology Testing on High-grade Cervical Intraepithelial Neoplasia at 48 Months - The HPV FOCAL Randomized Clinical Trial” was published this week in the Journal of the American Medical Association.
The team of researchers included 19,009 women over the age of 25 years and screened them using either Pap test alone or HPV testing alone. The participants were recruited from 224 clinicians between January 2008 and May 2012 and the patients were all followed up for four years until December 2016. From the participants, 9,552 women were screened using HPV test and those who were negative for the test came back after four years for a check if they had a pre-cancerous or cancerous lesion. Similarly 9,457 women were tested using Pap test and they too returned at 24 and 48 months for a repeat check up to see if they had cervical cancer. At the end of the four years the women were tested using both tests.
After four years it was found that almost six women in 1,000 who had been screened as negative with Pap test alone had pre-cancerous lesions while two women in 1,000 with negative HPV testing showed precancerous lesions.
In an accompanying editorial in the journal Dr. L. Stewart Massad, a professor of obstetrics and gynecology at Washington University School of Medicine in St. Louis said that Pap tests may soon be replaced by HPV tests. HPV test is more accurate, leads to earlier diagnosis and also increases the interval between screening.