Even low-dose birth control pills can raise breast cancer risk
Dec 07 2017 by Kathy Alvarado
Other studies had shown about the same breast cancer risk for older versions of birth control pills.
Women taking modern formulations of the pill have a 20 percent increased risk of breast cancer compared with those who've never been on hormonal contraception, the study of nearly 2 million Danish women found. "Yes, hormonal contraception may increase your risk for breast cancer, but the absolute risk of breast cancer is small".
The new paper estimated that for every 100,000 women, hormone contraceptive use causes an additional 13 breast cancer cases a year.
Dr Chris Zahn, ACOG's vice president for practice activities, acknowledged a link between breast cancer risk and hormone use, but urged concerned women to consult a trusted medical provider before making changes.
Beyond the fact that they provide an effective means of contraception and may benefit women with menstrual cramping or abnormal menstrual bleeding, "the use of oral contraceptives is associated with substantial reductions in the risks of ovarian, endometrial, and colorectal cancers later in life".
The research also suggests that the hormone progestin - widely used in today's birth control methods - may be raising breast cancer risk. Women who used any form hormonal contraception for more than 10 years (1.38, 95% CI 1.26-1.51) had a higher risk compared to those who reported less than 1 year of use (1.09, 95% CI 0.96-1.23)(P=0.002), they wrote online in the New England Journal of Medicine.
The researchers found a similarly increased breast cancer risk in birth control pills that only contain progestin, as well as in IUDs that release progestin.
Still, experts cautioned that the absolute risk of breast cancer for any one woman on the Pill remains very low.
"No one should take (oral contraceptives) without careful thought, but the advantages in avoiding an unwanted pregnancy will usually more than outweigh the very slightly increased risk of breast cancer", said Ashley Grossman, emeritus professor of endocrinologyat Britain's University of Oxford. Over the years, makers of birth control pills and hormone replacement therapy for women past menopause have reduced the amount of estrogen in their products.
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"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)".
There was optimism that newer, low-dose contraceptives would lower the breast cancer risk, but these results have dashed those hopes, said Gaudet, who wasn't involved in the research.
Women should discuss their contraceptive options with their doctor or gynecologist, Gaudet and Morch said. Yet the new study found increased risks that were similar in magnitude to the heightened risks reported in earlier studies based on birth control pills used in the 1980s and earlier, Hunter said.
He also added the risks associated with hormonal contraception must be weighed against the benefits.
"The relative risk increase in this study is only 1.2 on average". 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. Any woman's risk of breast cancer goes up as she gets older. A 20 per cent increase raises her risk to 1.74 per cent, or 1 in 57.
Most breast cancers are fueled by estrogen.
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.
"Nothing is risk-free, and hormonal contraceptives are not an exception to that rule", said Dr. Øjvind Lidegaard, the paper's senior author. Condoms and diaphragms do not deliver hormones.