Common IUD contraceptive devices may increase the risk of breast cancer, research suggests.
Women who used hormonal IUDs that slowly release the contraceptive levonorgestrel were 40 percent more likely to be diagnosed with the disease in at least five years than women who used other birth control methods.
Among women who used them for more than a decade, the risk increased to 80 percent.
About one in five sexually active women in the US and one in six in the UK use IUDs, which are inserted into the uterus by a doctor and last between three and eight years. Many women opt for these because they don’t have to remember to take a pill every day.
The researchers noted that while the overall risk is low, since IUDs are used long-term, “information about breast cancer risk should accompany discussions about benefits and risks.”
Researchers in Denmark found that using a hormonal IUD can increase the risk of breast cancer by 40 percent
The graph above indicates how breast cancer rates have increased by one percent each year in all age groups, but slightly faster among women under 50.
Experts suggest this may be due to an influx of hormones such as estrogen and progesterone that bind to breast proteins and feed certain forms of cancer.
They can also be riskier than pills or other birth control methods because they are used for years, sometimes up to a decade.
A preview of the new research was published Monday in JAMA. However, the full study has not yet been published.
The Danish Cancer Institute team evaluated 157,190 girls and women aged 15 to 49 between 2000 and 2019. The average age of the participants was 38 years.
Half of the participants were prescribed a hormonal IUD with levonorgestrel, the same drug found in the morning-after pill, while the other half used other birth control methods or no birth control.
In the United States, levonorgestrel is used in the Kyleena, Liletta, Mirena, and Skyla IUDs.
Participants were also divided into groups based on how long they used IUDs: zero to five years, five to 10 years, and 10 to 15 years.
The researchers found that, on average, hormonal IUDs led to a 40 percent increased risk of breast cancer compared to other forms of birth control.
Those who used this form of birth control had a 30 percent increased risk after zero to five years and 40 percent for five to 10 years.
The likelihood was higher for the long-term group, as women who used hormonal IUDs were 80 percent more likely to develop breast cancer after 10 to 15 years of use compared to those who used other contraceptives.
The team noted that the risk of breast cancer from taking birth control pills was around 20 percent.
The researchers did not explain why hormonal IUDs may increase the risk of breast cancer, although experts have suggested that the influx of hormones such as progesterone and estrogen may stimulate the growth of cancer cells in some forms of breast cancer.
These hormone-sensitive cancers include estrogen receptor-positive (ER-positive) and progesterone receptor-positive (PR-positive) breast cancers, which contain proteins that bind to hormones and trigger the growth of cancer cells.
There were several limitations to the research. The study looked at correlation rather than causation and the full results have not been published.
It is also unclear what types of breast cancer the women were diagnosed with.
The findings come at a time when breast cancer is increasing among American women under 50, which experts have suggested could be due to changes in reproductive habits, such as women having children later or starting pregnancy. menstruation before.
About 310,000 women will be diagnosed with breast cancer this year, the American Cancer Society estimates, and about 42,000 will die.