YOUNG women who go years between smear tests are putting themselves at increased risk, according to a new study.
Certain types of abnormalities that can lead to cervical cancer may be missed when there is a large gap between smears.
Guidelines in the US recommend that women under 21 don't need to be screened for cervical cancer and smears can be done once every three years after that.
Lisa Barroilhet, of the University of Wisconsin Hospital in Madison and the study's lead author, said she agrees with those recommendations and her findings are not a reason to change them.
But Pap smears have picked up abnormalities that helped find problems further up the cervix that could lead to cancer, she said.
Ms Barroilhet and her team reviewed the records of 242 women with adenocarcinoma in situ (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 smears, so they're not a focus of smear-related guidelines, she added.
However, she and colleagues found most young women in the study were diagnosed with AIS because of other abnormal lesions picked up on smears that led to morebiopsies.
That was the case for 16 of the 17 women diagnosed with AIS before age 21, they wrote in Obstetrics & Gynecology.
Even though smears weren't designed to catch adenocarcinoma precursors, the findings mean less-frequent smears could lead to more of those full-on cancers developing, Barroilhet said. That's especially a concern because they can be a faster-growing type of cancer.
But Rebecca Horvat, a pathologist from the University of Kansas Medical Centre representing the American Society for Clinical Pathology, said most abnormal lesions still take years to develop into adenocarcinomas. "It doesn't do (that), as soon as you get it, you get a cancer," said Horvat, who wasn't involved in the new study. "It can be easily picked up every three years."