The American Cancer Society (ACS) has released new cervical cancer screening guidelines that call for less screening in most women. The recommendations were published July 30 in the ACS flagship journal, CA: A Cancer Journal for Clinicians.
The new recommendations suggest beginning screening at age 25, instead of age 21. Moreover, the guidelines stipulate that most women need screening only once every five years using only the human papillomavirus (HPV) test.
The previous ACS cervical cancer screening guidelines were released in 2012 and called for screening to start at age 21 and testing every five years using both HPV and Pap tests (called cotesting). The ACS committee did not make any changes to the age at which time screening can stop — 65 for most women who have adequate prior negative screening results.
The new recommendations are based on recent research showing the HPV test is more accurate than the Pap test at predicting cervical cancer risk and can be done less often without compromising patient health and safety, according to the authors of the guidelines.
“When you do cotesting, the benefit is almost entirely from the HPV testing,” said Debbie Saslow, PhD, managing director for HPV-related and women's cancers at the American Cancer Society. “The Pap test offers very little added benefit to just doing an HPV test.”
Under the new regimen, women with normal test results would require only eight HPV tests over the years spanning age 25 to 65. Studies shows that a negative HPV test is linked to a very low cervical cancer risk.
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Guidelines Increasingly Endorse Less Frequent Testing
The new guidelines reflect a remarkable evolution in cervical cancer screening over the past four decades. In the 1980s and 1990s, Pap tests were conducted every year as a routine part of a woman’s annual checkup. Pap tests, also called Pap smears, look for changes in the cells lining the cervix that could advance to cervical cancer without treatment.
The HPV test, meanwhile, detects the HPV virus. Several aggressive strains of HPV have been identified as the major cause of cervical cancer. HPV also can cause genital warts and can lead to several other types of cancers, include oral cancer, anal cancer, and penile cancer, according to the Centers for Disease Control and Prevention (CDC).
Most people are eventually exposed to HPV through sexual intercourse, and most infections go away on their own without causing symptoms or problems. But in some women, the virus causes cellular changes that can lead to cancer, according to research published in February 2019 in American Family Physician.
Cervical cancer screening is considered a major success story in cancer prevention. Cervical cancer deaths in the U.S. have fallen from 2.8 per 100,000 women in 2000 to 2.3 per 100,000 women in 2015, according to the National Cancer Institute.
Starting screening at age 25 reflects the falling case rate, Dr. Saslow said.
“This goes back many, many years,” she said. “Back in the ‘80s, we would start Pap tests at age 18. Then it was changed to starting three years after first sexual intercourse, and then we moved it to age 21. We were inching forward because we knew we were overdoing things. We were the only country in the world screening teenagers.”
HPV Vaccine Has Decreased Risk Considerably
Another factor in the guideline revision is the increase in people who have received the HPV vaccine and are largely protected from cervical cancer, Saslow said.
The HPV vaccine became available in 2006 and protects against several aggressive strains of HPV. The vaccines are recommended for boys and girls starting around age 11, notes the CDC.
The more youths who are vaccinated, the less the virus circulates and infects people, she said, establishing herd immunity to HPV. Moreover, while the first HPV vaccine protected against two high-risk strains of the virus, the latest HPV vaccine protects against seven high-risk strains that can cause cancer.
“Even with only half of men and women now getting vaccinated — even though we are nowhere near where we want them to be — vaccination is already having a much bigger impact than we expected,” she said.
The guidelines are based on the best clinical outcomes, she adds, not on cost-saving considerations.
“Women should feel it’s completely safe,” Saslow said. “We are not risking their health to save money or any other reason other than we have the evidence that it’s safe to do.”
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ACS Guidelines and U.S. Preventive Services Task Force Guidelines Don’t Agree
The ACS guidelines stand in contrast to the current U.S. Preventive Services Task Force (USPSTF), an independent, volunteer panel of national experts in disease prevention and evidence-based medicine.
The USPSTF guidelines call for cervical cancer screening every three years using Pap tests for women ages 21 to 65. The options under the USPSTF guidelines for women ages 30 to 65 are every three years with Pap testing, every five years with HPV testing alone, or every five years with cotesting.
“The best starting age for us was 21,” said Carol M. Mangione, MD, the vice-chair of the USPSTF and chief of the Division of General Internal Medicine and Health Services Research at the University of California in Los Angeles.
“We looked very carefully at the various studies and our review of the research literature. We also had some modeling studies done that looked at the balance between the benefits and harm of various starting dates.”
Starting screening at a younger age may catch precancerous lesions earlier, she said. The potential harm is that precancerous lesions in younger women may clear up on their own, and detection could lead to unnecessary tests and treatment.
“There is this balance between starting early enough to treat early precancerous lesions and starting too early and potentially causing harm,” Dr. Mangione said.
The USPSTF recommends women ages 21 to 29 have screening with a Pap test every three years because HPV testing in this age group often detects harmless infections that will clear up on their own, she said.
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A Case for Confusion: Which Set of Guidelines Should You Follow?
The differing guidelines may cause confusion, Saslow acknowledged.
“We always like for guidelines to be the same because then people don’t have to choose which ones to follow and because most health plans are required to follow the government guidelines,” which rely on the USPSTF, she said.
Mangione says the differences in screening guidelines are marginal. Any screening is better than no screening, she said.
“The important thing is that screening for cervical cancer saves lives,” she said. “Certainly, individual patients can discuss what starting date they wish to follow with their doctors. The big point is: “This is a highly effective condition to screen for,” she said.
“Cervical cancer happens in women who aren’t screened. Women who have poor access to care, very low income, who don’t have health insurance and some minority groups are much more likely to be diagnosed with cervical cancer.”