Less frequent Pap smears may miss cancer precursors

Certain types of cervical abnormalities that can lead to cancer may be missed when young women go years between Pap smears, a new study suggests.

Last year, the government-backed U.S. Preventive Services Task Force said women under 21 don't need to be screened for cervical cancer and Pap smears can be done once every three years after that.

Those guidelines broadly agreed with others released by the American Cancer Society, the American Society for Colposcopy and Cervical Pathology and the American Society for Clinical Pathology.

The new study's lead author, Dr. Lisa Barroilhet, said she agrees with those recommendations and that her findings are "absolutely" not a reason to change them.

"Any time you have new guidelines, you just want to make sure you're not assuming this is going to be the right thing long term for every patient," Barroilhet, from the University of Wisconsin Hospital in Madison, told Reuters Health.

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She and her colleagues reviewed the records of 242 women with adenocarcinoma in situ, or AIS - cervical abnormalities that can lead to adenocarcinoma, one form of cervical cancer.

Those cancers occur further up the cervix than the squamous cell carcinomas typically caught by Pap smears, Barroilhet explained - so they're not the focus of Pap-related guidelines.

However, she and her colleagues found most young women in their study were diagnosed with AIS because of other abnormal lesions picked up on Pap smears that led to more testing and biopsies.

That was the case for 16 of the 17 women diagnosed with AIS before age 21, they wrote Thursday in Obstetrics & Gynecology.

Even though Pap smears weren't designed to catch adenocarcinoma precursors, the findings mean less-frequent Paps could lead to more of those full-on cancers developing, Barroilhet told Reuters Health. That's especially a concern because adenocarcinomas can be faster growing than squamous cell carcinomas, she said.

But Rebecca Horvat, a pathologist from the University of Kansas Medical Center representing the American Society for Clinical Pathology, said most abnormal lesions still take years to develop into adenocarcinoma.

"It doesn't go, as soon as you get it, you get a cancer," Horvat, who wasn't involved in the new study, told Reuters Health. "It can easily be picked up every three years."

She said the main challenge with moving to screening every three years may be a psychological one for women who have spent years getting their annual Pap.

The American Cancer Society estimates 12,340 U.S. women will be diagnosed with cervical cancer in 2013. Up to four times as many may develop AIS.

Because both adenocarcinomas and squamous cell carcinomas can be caused by human papillomavirus, or HPV, Barroilhet said preventing the sexually transmitted infection remains a public health priority.

"The best way to prevent any of this is HPV vaccination," she said.