Monday, 11 December, 2017

Birth control linked to 20% higher risk of breast cancer

Even New Birth Control Pills May Raise Women's Breast Cancer Risk Some birth control raises risk of breast cancer, study says
Melissa Porter | 07 December, 2017, 09:08

Studies of older birth control pills have shown "a net cancer benefit" because of lowered risk of cancer of the colon, uterus and ovaries despite a raised breast cancer risk, said Mia Gaudet, a breast cancer epidemiologist at the American Cancer Society. "But we should make an individual assessment-doctor and a woman, together-to see what is the most appropriate thing for her to use".

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 study, which used all of Denmark as its sample, followed almost 1.8 million women of childbearing age for over a decade on average, drawing data from national prescription and cancer registries.

They found that women taking estrogen/progestin birth control pills have about a 20 percent increased risk of breast cancer.

The longer women used hormonal contraception, the greater their risk of breast cancer, the researchers found.

A hormone specialist at Brigham and Women's Hospital who deals with contraceptive issues says the study shouldn't alarm those taking oral contraceptives.

The study of nearly 2 million women in Denmark looked at women using birth control methods such as the pill, NuvaRing, or implants.

"There had been some changes to oral contraceptive formulations in the '90s, and there was the hope those formulations would result in a lower risk of breast cancer", said Gaudet, who was not part of the study.

In a commentary accompanying the new study, which was published in the New England Journal of Medicine, David J. Hunter, a professor of epidemiology and medicine at the University of Oxford, said the new study did not find that any modern contraceptives were risk-free.

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, it was commonly thought that the newer low-dose estrogen options significantly decreased - or even eliminated - that risk.

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. Still, the additional risk would result in a comparatively few additional cases of breast cancer, the researchers said.

"Progestin-only products also increased the risk of breast cancer", Morch noted. "So, many calculations suggest that the use of oral contraceptives actually prevents more cancers than it causes".

For some perspective, about 252,710 American women were diagnosed with breast cancer in 2017, according to estimates from the National Institutes of Health; 12.4 percent of women will hear the diagnosis at some point in their lives. A 20 per cent increase raises her risk to 1.74 per cent, or 1 in 57.

But the researchers add, while this may sound scary, the overall risk of breast cancer remains small for many women; and the pill has its benefits. By contrast, there was no increased risk for breast cancer seen in women who used hormones for less than one year. However, using hormonal contraception for 10 years was linked with a 40 percent increase in the risk of breast cancer, compared with those who had never used hormonal contraception.

IUDs infused with hormones also appear to pose a risk, Morch said, so "so there's a lot of things to take into account when deciding what type of contraception to use".