Contraceptive coil 'nearly halves cervical cancer risk'

13^th September 2011 - Women who use the contraceptive coil might be protecting themselves against cervical cancer, a large international study has suggested.

Researchers found that contrary to popular belief, the coil - otherwise known as an intrauterine device (IUD) - almost halved the risk of developing cervical cancer.

One major UK cancer charity described the findings as "interesting" but said a number of questions remained unanswered.

Cervical cancer and HPV

About 2,800 women are diagnosed with cervical cancer in the UK each year. The disease is usually caused by the human papilloma virus (HPV), although most women who have HPV will not get cervical cancer.

Researchers from Spain, France and the Netherlands examined ten case control studies of cervical cancer drawn from eight countries, and 16 studies of HPV [human papilloma virus] carried out across four continents. The data involved 2,205 women with cervical cancer who were matched with 2,214 women without the disease and 15,272 healthy women from the HPV surveys.

Long-lasting protection

After adjusting for a range of factors such as the number of smear tests, number of sexual partners and age at first intercourse, the researchers found that the risk of developing cervical cancer was reduced by nearly half in the first year of use, with the protective effect remaining significant even after 10 years use.

Writing in The Lancet Oncology, the authors say "the associations found in our study strongly suggest that IUD use does not modify the likelihood of prevalent HPV infection, but might affect the likelihood of HPV progression to cervical cancer".

The authors also found that length of time a woman used an IUD did not seem to significantly affect her risk of getting cervical cancer.

Explanations

A number of possible explanations for this protective effect are put forward in the study including that the process of inserting or removing an IUD destroys precancerous lesions or that it induces chronic mucosal inflammation and a long lasting immune response, thereby reducing the likelihood of HPV progression.

They conclude: "Our data suggest that use of IUDs significantly reduces the risk of cervical cancer and that this effect does not seem to be due to differences in screening histories between users and non-users."

Unanswered questions

Commenting on the research, Jessica Harris, health information manager at Cancer Research UK, said in an emailed statement: "This study opens up an interesting new avenue for research, but there are still lots of unanswered questions. For example, it’s not clear how this effect is happening, and whether it’s IUD use itself that is causing the reduced risk, or something else that is linked to both IUD use and cervical cancer.

"Answering these questions could help us understand more about how cervical cancer develops after HPV infection."

In a linked Comment to the research in the same edition of The Lancet Oncology, Karl Ulrich Petry from the Klinikum Wolfsburg in Germany writes that the "surprising results should spark new research and might lead to revision of our current understanding of the genesis of cervical cancer".

Petry adds: "Today´s standard information for patients - that less than 1% of HPV infections progress to cancer - probably just reflects the failure rate of screening in developed nations’ health-care systems. The 6•5% lifetime risk for cervical cancer observed in remote areas without screening probably mirrors the true natural risk."