US health panel cautious on HPV screening vs Pap
October 20, 2011
Last Updated: 2011-10-19 10:06:25 -0400 (Reuters Health)
By Alina Selyukh
WASHINGTON (Reuters) - A U.S. government-backed medical panel on Wednesday took a cautious view of a new generation of cervical cancer tests, discouraging women under the age of 30 to screen for human papillomavirus as a way to prevent cancer.
In proposing changes to its 2003 guidelines on cervical cancer, the U.S. Preventive Services Task Force (USPSTF) said it still didn't have enough evidence to weight the health benefits and harms of HPV testing in women older than 30.
Overall, the panel maintained that a Pap smear test in women between 21 and 65 years of age "substantially" reduces the number of cervical cancer cases and deaths.
The panel, comprised of primary care physicians who are experts at evidence-based research, is highly influential in setting the tone for primary care practice.
It must weigh the potential benefits of early detection of disease through screenings against the potential harms to healthy patients who may be subjected unnecessarily to more invasive procedures or side-effects.
Earlier this month, the task force came under fire from doctors and cancer patients after recommending against prostate cancer screening in healthy men.
It was the subject of a similar controversy in 2009 after recommending that doctors scale back on routine mammograms in women in their 40s and 50s to prevent breast cancer.
Under President Barack Obama's healthcare overhaul, the services recommended by USPSTF would also have to be covered by insurance companies with no co-pays or deductibles.
On Wednesday, the task force largely aligned with general practice and cancer societies' guidelines on screening for cervical cancer it terms of frequency and age group-specific recommendations.
Maintaining the recommendation of screening women every three years, the panel said it found "little to no benefit" in screening women older than 65 who had been previously tested and no impact on women younger than 21.
Previously, USPSTF's recommendations applied to women of 21 years old or within three years of becoming sexually active.
However, USPSTF was more skeptical of HPV testing and so-called "liquid-based" Pap tests, which have largely replaced the conventional Pap smear in the United States.
After reviewing all clinical data available on the subject, the panel recommended against HPV tests, alone or in combination with a Pap, in women under 30, noting that screening for HPV causes more false positive cancer results than the Pap smear alone.
"There are no clinically important differences between liquid-based and conventional cytology" in cervical cancer detection, the task force said. For women over 30, evidence remains insufficient to weigh HPV test harms and benefits.
HPV is a common virus that causes warts, including genital warts. Usually, the immune system clears the infection, but persistent infection with certain strains of HPV leads to cervical cancer in some women.
In recent years, tests for those "high-risk" HPV strains have been developed to help in screening for the disease. A few HPV tests are approved for use, along with Pap tests, for screening women age 30 or older. In younger women, the HPV virus, while common, often clears out on its own.
Every year, about 12,000 U.S. women are diagnosed with cervical cancer and a third of them die from it. HPV, a sexually-transmitted virus, is the most common cause of such cancer, which predominantly strikes middle-aged women.
In a regular Pap, a doctor swabs or scrapes cells from the cervix to examine them under a microscope to find cancer or precancerous changes. Some have raised concerns that the Pap may not be able to detect some cell changes, but the routine test is greatly credited for the steep decline in cervical cancer deaths the United States has seen since the 1950s.
With HPV tests, doctors analyze a swipe of cells for presence of viral DNA. The liquid-based Pap version allows the cervix cells to be used for HPV testing.
USPSTF is collecting public comment on the proposed recommendation changes. To see them, see 1.usa.gov/4xXexl.