Researchers have found a slight breast cancer risk linked to the use of injectable contraceptives, it has been revealed.
Younger women who use a particular type of injectable contraceptive for a year or more double the risk of developing breast cancer while they are using the treatment, a US study has found.
In the first large-scale study in the USA, Dr Christopher Li, breast cancer epidemiologist at the Fred Hutchinson Cancer Research Centre, Seattle, found that women who had used depo-medroxyprogesterone acetate (DMPA) for 12 months or more had a 2.2-fold greater risk of invasive breast cancer.
He also found that risk lessened within months of discontinuing the contraceptive.
Women who used DMPA for less than a year or who had stopped using it more than a year earlier had no increased risk of breast cancer.
The study involved 1,028 women, aged 20 to 44, from the Seattle area who had been diagnosed with breast cancer and 919 women of the same ages who did not have a history of breast cancer. Of these, about 10 per cent reported using DMPA.
“While DMPA is widely used by women throughout the world, there are limited data on the association between DMPA and breast cancer incidence,” said Dr Li, a member of the Hutchinson Center’s Public Health Sciences Division who led the study, which is published in Cancer Research.
“Although breast cancer is rare among young women and the elevated risk of breast cancer associated with DMPA appears to dissipate after discontinuation of use, our findings emphasise the importance of identifying the potential risks associated with specific forms of contraceptives given the number of available alternatives,” continue the authors.
“In the United States many women have numerous options for contraception, and so it is important to balance their risks and benefits when making contraceptive choices,” Li added.
Effect of depo-medroxyprogesterone acetate on breast cancer risk among women 20-44 years of age. Li C et al. Cancer Research April 15 2012. doi:10.1158/0008-5472.CAN-11-4064
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