Most women can wait three to five years between checks for cervical cancer, depending on their age and test choice, new U.S. guidelines say.

Many medical groups have long recommended a Pap test every three years for most women. The new advice from the American College of Obstetricians and Gynecologists says that's true for women ages 21 to 29 whose Paps show no sign of trouble.

In a Pap test, cells are scraped from the cervix to look for early signs of cancer. In a Pap test, cells are scraped from the cervix to look for early signs of cancer. (Craig Lassig/College of American Pathologists/Associated Press)

But for healthy women ages 30 to 65, the preferred check is a Pap plus a test for the cancer-causing HPV virus, the group concluded. If both show everything's fine, they can wait five years for further screening.

The guidelines from the largest OB-GYN organization in the U.S. agree with advice issued earlier this year by a government panel, the American Cancer Society and other medical groups — showing growing consensus that it's safe for the right women to wait longer between Paps.

Cervical cancer grows so slowly that regular Pap smears, which examine cells scraped from the cervix, can find signs early enough to treat before a tumour even forms.

Canadian guidelines recommend that a woman begin having Pap tests within three years of becoming sexually active or by age 21. A woman should have a Pap test once per year until she has had two normal test results in a row, and then she need only be tested every three years.

Women should continue having tests until they are at least 70 years of age, the Federation of Medical Women of Canada and the Society of Obstetricians and Gynecologists of Canada said Tuesday.

Certain strains of HPV, the human papillomavirus, cause most cervical cancer, but the infection has to persist for a number of years to do its damage. HPV is a common virus in young women, whose bodies usually clear the infection on their own. Thus, health groups don't recommend routinely testing 20-somethings for HPV because it would cause too many false alarms.