April 29 (HealthDay News) -- Screening for cervical cancer reduces the risk for all types of the disease in women of all ages, say Swedish researchers. They also concluded that better follow-up of women who have cervical cancer screening could lower rates of the disease.

The researchers reviewed data from the National Cervical Cancer Screening Registry on 1,230 cervical cancer patients diagnosed between 1999 and 2001, and 6,124 age-matched women who hadn't been diagnosed with cervical cancer.

Women who hadn't had a Pap smear screening test within the recommended three-year interval were 2.5 times more likely to be diagnosed with cervical cancer than women who had regular Pap tests. Women who didn't have regular screening were also nearly five times more likely to be diagnosed with advanced cervical cancer than those were had regular screening.

Regular screening reduced the risk for all types of cervical cancer and reduced the risk of women between ages 23 and 30, which were new findings, according to the researchers.

They noted that screening didn't completely protect women from cervical cancer. Women who were screened at the recommended interval and were found to have abnormal cells were 7.6 times more likely to develop cervical cancer than women who were screened and had normal results.

Women with abnormal Pap results accounted for 11.5 percent of all cervical cancer cases. This increased risk was not noted in women diagnosed with advanced cervical cancer.

The study was published online April 29 in the Journal of the National Cancer Institute.

The researchers said their findings show that irregular screening is the most important risk factor for incident cervical cancer and that abnormal smears, if not followed up by a biopsy, are also an important risk factor.

In an accompanying editorial, Jack Cuzick, of the Cancer Research UK Centre in London, emphasized the importance of systematic audits of cancer screening programs.

"Audits, such as the one described (in this study), need to become routine within screening programs if screening is to achieve its full potential," Cuzick wrote. These reviews identify areas of screening programs that are ineffective and need to be restructured and improved.

SOURCE: Journal of the National Cancer Institute, news release, April 29, 2008