"If you look at the absolute risk, the likelihood of getting breast cancer amongst current users, was really only approximately 13 women per every 100,000, so, it's really a slightly increased risk overall", said Dr. Starck.
According to the New York Times, older forms of birth control with high doses of estrogen were known to increase the risk of breast cancer in women.
While contraceptive drugs that contain oestrogen have always been suspected of increasing the likelihood of breast cancer, researchers had expected smaller doses of the hormone, often combined with the drug progestin, would be safer, said Lina Morch, an epidemiologist at Copenhagen University Hospital who led a study analysing the records of 1.8 million women in Denmark. Because of fewer users, the results for the patch, vaginal ring, implant and progestin shot were less clear, but the analysis didn't rule out an increased breast cancer risk for those methods. In the meantime, women who are using oral contraceptives might want to speak to their doctors about use before age 35 and after age 35. The researchers tracked almost 1.8 million women starting in 1995 and compared those who purchased birth control methods with women who developed breast cancer.
"The risk of breast cancer was higher among women who now or recently used contemporary hormonal contraceptives than among women who had never used hormonal contraceptives, and this risk increased with longer durations of use; however, absolute increases in risk were small".
Although modern birth control pills have a lower dose of estrogen than past versions, they are still linked to breast cancer, a new Danish study suggested.
"Gynecologists just assumed that a lower dose of hormone meant a lower risk of cancer". Most of the cases were in women over the age of 40.
In an accompanying editorial, David Hunter, professor of epidemiology and medicine at the Nuffield Department of Population Health in the United Kingdom, said that the link between oral contraceptives and breast cancer is already well-established. Any woman's risk of breast cancer goes up as she gets older. "However, the researchers did allow statistically for most of the important factors that might also be involved, and they give good reasons why the differences in risk that they found are likely to be causally related to the contraceptives".
"Unfortunately this was not the case and additional research is needed to tweak the formulation".
However, Hunter also stresses that "breast cancer remains a relatively rare disease in younger women". And if it's not needed to take hormonal contraceptions, it might be worth considering using other methods like the copper IUD or barium if it's - like condoms, for instance. "But this study reminds us this is an important objective". As research began to link estrogen to breast cancer, the FDA took off the market any formulations that had more than 50 micrograms of estrogen, Gaudet said.
Despite the risk, women will continue to use the pharmaceuticals, Morch said.
Keep in mind, oral contraceptives have benefits as well. And so many calculations suggest that use of all contraceptives actually prevents more cancers than it causes. However, it was commonly thought that the newer low-dose estrogen options significantly decreased - or even eliminated - that risk.