WASHINGTON - Most women in their 20s can have a Pap smear every two years instead of annually, under new guidelines that say that’s enough to catch slow-growing cervical cancer.

The change by the American College of Obstetricians and Gynecologists comes amid a controversy in a separate debate over when regular mammograms to detect breast cancer should begin. The timing of the Pap guidelines is coincidence, said ACOG, which began reviewing its recommendations in late 2007 and published the update yesterday in the journal Obstetrics & Gynecology.