(CBS) Pregnancy may not be the only thing intrauterine devices (IUDs) prevent. Women who use the contraceptive devices are about half as likely to develop cervical cancer, a new international study showed. That was true even though the women in the study were no less likely to be infected with the human papillomavirus (HPV) that causes cervical cancer.
"It was a little unexpected," study author Dr. Xavier Castellsague, of the epidemiological research program at Llobregat Hospital in Catalonia, Spain, told Reuters. "The data (available) before we did this study were very inconsistent, so we didn't expect to find such a strong association with this protective effect."
Previous research had shown that use of IUDs reduce the risk for endometrial cancer, the authors of the study wrote. But it was unclear whether the devices - which are inserted into a woman's uterus to keep her eggs from being fertilized by sperm - would have any effect on cervical, the second most common cancer in women.
For the study - published in the journal The Lancet Oncology - the researchers analyzed data from dozens of previous studies involving more than 20,000 women. The researchers found that IUD users had lower rates than other women of two major forms of cervical cancer, squamous cell carcinoma (44 percent lower) and adenocarcinoma/adenosquamous carcinoma (54 percent lower).
The study showed only and association and didn't prove that IUD use help prevent cervical cancer. But experts say that inserting or removing an IUD might destroy precancerous cells, the Associated Press reported. Another possibility is that insertion or removal causes inflammation that evokes an immune response that prevents the progression of HPV infection to cervical cancer.
Should women worried about cervical cancer ask a doctor about using an IUD to prevent cervical cancer? It's too soon for that, Dr. Carol Brown, a cervical cancer specialist at New York City's Memorial Sloan-Kettering Cancer Center, told USA Today. Dr. Brown, who wasn't involved in the new study, said the findings need to be confirmed with more rigorous trials.
Only two percent of American women use IUDs, although the devices are more popular around the world, HealthDay reported. The plastic devices - which use copper or progesterone in plastic as the contraceptive agent - are highly effective against pregnancy but do not protect against sexually transmitted diseases and must be prescribed and inserted by a doctor.
Cervical cancer used to be the leading cause of cancer death among women in the U.S. In recent years, the cancer has become much less deadly, in part because so many women get regular Pap tests that can detect the disease in its earliest stages.
WebMD has more on cervical cancer.