Women ages 30 to 65 may decide how often they want to get screened for cervical cancer depending on the test they choose, according new draft recommendations for cervical cancer screening from the U.S. Preventive Services Task Force. Testing every three years requires a Pap smear, and testing every five years requires a test for human papillomavirus (HPV), the virus that causes nearly all cervical cancers.
"A woman going to her provider for a visit would want to talk with her doctor about the last time she was screened, what type of screening she had, which one to have next and what the timing of that should be," says Maureen Phipps, chair of obstetrics and gynecology at the Warren Alpert Medical School of Brown University in Providence, R.I., and a member of the task force. The draft recommendations update the 2012 USPSTF recommendations.
Every year in the US, nearly 13,000 women develop cervical cancer and just over 4,000 die from it, according to the American Cancer Society. "We really want to emphasize that cervical cancer is a devastating disease and that screening is very important," Phipps says. "We want to catch it at an early stage so we can begin treatment."
Cervical cancer screening is one of the greatest success stories in cancer prevention history: widespread screening cut the cancer's incidence and mortality in half over three decades. An estimated 2.3 women per 100,000 died from the disease in 2011, compared to 5.6 women per 100,000 in 1975. Screening currently saves more than 4,000 lives a year, the American Cancer Society estimates.
Both the Pap test and the HPV test are done on a sample of cells collected from the cervix. The Pap test (named for the scientist who pioneered the technique) looks for abnormal cell growth that may indicate cancerous or precancerous conditions. The HPV test looks for types of the virus that can cause cancer in women and men.
The USPSTF is an independent panel of unpaid experts who review existing evidence for preventive measures, such as disease screenings and counseling services, to create national evidence-based recommendations. The recommendations often influence what services and medications insurance companies will pay for.
"We encourage public comment because we want to be sure we get it right," Phipps says. The public comment period runs from September 12 through October 9. Then the task force will decide whether to adopt the draft recommendations or issue a revised version of them.
Cervical cancer screening recommendations differ by age, and the USPSTF is only recommending a change for middle-aged women. Previous recommendations remain in place:
- Cervical cancer screening should not begin until at least age 21 regardless of sexual history, unless a person has an HIV infection or another immunocompromising condition.
- People ages 21 to 29 should not receive an HPV test, but should receive a Pap test every three years.
- People over age 65 do not need screening unless they fall into a high risk group, such as an inadequate history of negative screening, a history of high-grade dysplasia or prenatal diethylstilbestrol (DES) exposure.
If adopted, the new USPSTF recommendations would more closely align with guidelines from the American College of Obstetricians and Gynecologists (ACOG), the American College of Physicians (ACP) and similar organizations. The main difference is that those organizations recommend the Pap test every three years or co-testing — a Pap with an HPV test — every five years for people ages 30 to 65. The USPSTF is the first to include a recommendation for an HPV test without the Pap.
One HPV test is currently FDA-approved as a stand-alone cervical cancer screening tool. It can detect 14 strains of the virus, including HPV 16 and 18, which account for 70 percent of all cervical cancers.
"Most of the value of co-testing is from the HPV test because it's specific --when it's negative, it's really negative — and it's very sensitive, so if you have a positive test, we're not going to miss people who have pre-cancer or cancer," says Kevin Ault, an assistant professor of OB-GYN at the University of Kansas Medical Center. "We've known for at least a couple decades that the Pap smear by itself misses some women with precancerous change. Some women have negative Pap smear but do have something, so we added the HPV test to catch it."
But a positive HPV test does not guarantee a person will develop cervical cancer. HPV is extremely common: about 79 million people have it at any given time, and nearly all sexually active people contract it at least once. Most infections clear on their own. But certain strains carry a higher risk for cervical cancer. It takes 10 to 30 years for an HPV infection to develop into cancer, though, so testing more often than once every five years would not catch cancer any earlier and may lead to unnecessary interventions. The HPV test is not recommended for screening younger women because the virus is so widespread that its use would likely lead to overtesting and overdiagnosis.
"As we go further down in the age range, you're going to find a lot of infections that probably never will grow up to be cervical cancer," Ault says. "You're going to scare women to death, and they're going to have a lot of extra tests and surgery at a young age that may not be necessary."
Another concern about the HPV test is stigma, Ault says. With his patients, he explains what HPV test results mean (and don't mean) before women have one so he can answer questions and clear up misconceptions. A positive test will most likely lead to retesting, plus a Pap smear 12 months later and/or subtyping to see if the infection is a high-risk strain.
If a positive test accompanies an abnormal Pap smear, the physician does a colposcopy, looking at the cervix with a scope. If a woman has precancerous cells, several treatment options exist.
"Once we've treated you, and your HPV test is negative, you're back to a normal risk," Ault says.
Ault expects the HPV test to become more routine, but said it typically takes three to five years to change clinical practice. A rapidly evolving understanding of the disease, however, has led to frequent, sometimes inconsistent changes to screening guidelines. Guidelines from all groups — USPSTF, ACOG, ACS, American Society for Colposcopy and Cervical Pathology (ASCCP), American Society for Clinical Pathology (ASCP) and Society of Gynecologic Oncology (SGO) — are very similar, but all are more complex than the previous standard.
"It wasn't that long ago that annual Pap smears were an option, and then we've changed those guidelines every few years," Ault says. "It's been hard to stabilize clinical practice because we've changed so frequently. You can imagine how confusing it is for patients."
The danger of that confusion is missed screenings, particularly among those with low health literacy or limited access to health care.
"We still have to get women into these screens," Ault says. "We have to figure out how to reach those groups if we're really going to drive down cervical cancer rates in this country."
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