Intrauterine devices (IUDs) can reduce women's risk of developing cervical cancer by about a third, possibly because they trigger an immune response that kills off human papillomavirus (HPV), the virus that causes the disease.
IUDs And The Female Immune System
An IUD is a T-shaped object placed inside a woman's uterus to prevent pregnancy. There are two types of IUDs: the copper IUD and the hormonal IUD. The copper IUD inhibits sperm motility, preventing sperm from traveling through the cervical mucus, while the hormonal IUD releases a hormone that thickens the cervical mucus, keeping sperm from reaching the uterus.
Victoria Cortessis, from the University of Southern California's Keck School of Medicine, and colleagues suspected that the device might influence cervical cancer risk because it manipulates the female immune system.
"IUD in the uterus stimulates an immune response, and that immune response very, very substantially destroys sperm and keeps sperm from reaching the egg," Cortessis said. "It stands to reason the IUD might influence other immune phenomenon."
To verify this, they scoured through studies that measured the use of IUD and cases of cervical cancer.
Reduced Cervical Cancer Risk
In 16 studies that involved nearly 5,000 women who developed cervical cancer and more than 7,500 women who did not develop the disease, researchers found evidence suggesting that women who used the contraceptive device have a 30 percent reduced risk of getting cervical cancer than those who did not use it.
"Invasive cervical cancer may be approximately one third less frequent in women who have used an IUD. This possible noncontraceptive benefit could be most beneficial in populations with severely limited access to screening and concomitantly high cervical cancer incidence," the researchers wrote in their study, which was published in the journal Obstetrics & Gynecology on Nov. 7.
Cervical Cancer Is Treatable
Researchers said that the findings could have important implications in cancer prevention.
"The pattern we found was stunning. It was not subtle at all," Cortessis said. "The possibility that a woman could experience some help with cancer control at the same time she is making contraception decisions could potentially be very, very impactful."
Based on 2014 data, more than 12,500 women in the United States were diagnosed with cervical cancer. In 2012, there were more than half a million cervical cancer cases worldwide. Of those who died, 90 percent were from low- and middle-income countries.
Cervical cancer is highly preventable particularly in Western countries where screening tests and a vaccine to prevent HPV infections are available. Cervical cancer is treatable and is associated with long survival when detected early.
