"The increased risk also with newer progestins in hormonal contraceptives has not been shown consistently before, though progestins in postmenopausal therapy has also been found to increase the risk of breast cancer", she added.
A new study is raising the alarm about the link between birth control and breast cancer. Out of those women, for every 100,000 participants, the use of hormonal birth control caused an additional 13 cases of breast cancer each year.
One thing reiterated by every doctor Newsweek spoke to: Women who are anxious about how their contraception might increase their risk of breast cancer should speak with their health care provider.
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. However, he noted that the clinical implications of this study "must be placed in the context of the low incidence rates of breast cancer among younger women", pointing out that most of the new breast cancer cases occurring in the study were among women using oral contraceptives over the age of 40. 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 link with cancer risk exists not only for older generations of hormonal contraceptives but also for the products that many women use today, according to a paper published Wednesday in the New England Journal of Medicine. "Contraception itself is a benefit, of course, but this study indicates it might be worth considering an alternative to hormone contraception, like the copper intrauterine device or barrier methods like condoms".
"However, the risk also with newer progestins was more consistent and convincing than expected, in particular the increased risk with hormone IUD (includes only progestin)".
"The relative risk increase in this study is only 1.2 on average". 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.
He also added the risks associated with hormonal contraception must be weighed against the benefits.
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The National Cancer Institute estimates that 12.4 percent of women born in the United States will develop breast cancer at some time during their lives.
In fact, birth control increases breast cancer risk about as much as drinking alcohol does, said Dr. Mary Beth Terry, an epidemiologist at the Columbia University Mailman School of Public Health. But the odds rose among women who used hormonal contraception for more than 10 years, the study found. The findings indicate that the hormone progestin is adding to breast cancer risk; some of the contraceptive pills and numerous IUDs included only progestin, Mørch said. Still, the additional risk would result in a comparatively few additional cases of breast cancer, the researchers said. For a 20-year-old woman, for example, the probability of developing breast cancer in the next 10 years is 0.06 per cent, or 1 in 1,732, according to breastcancer.org.
Mørch explained to MedPage Today that "there was a lack of evidence on contemporary hormonal contraception and risk of breast cancer".
The risk was 9 percent higher with less than one year of use and 38 percent higher with more than 10 years of use.
The new study looked at all women in Denmark ages 15 to 49 who had not had cancer, clots in their veins, or treatment for infertility.
"No type of hormone contraceptive is risk-free unfortunately", said lead author Lina Morch of Copenhagen University Hospital.