Contraceptive pill could increase breast cancer risk more than experts first thought, study finds

Nonetheless, experts say birth control has a positive effect on the lives of women

(Getty Images/iStockphoto)

Taking the contraceptive pill could increase your risk of breast cancer more than previously feared, new research suggests.

A study from the University of Michigan has revealed that some commonly prescribed birth control pills may quadruple levels of synthetic oestrogen and progesterone hormones.

Both of which are thought to play a part in stimulating breast cancers to grow, which is why some breast cancer patients are prescribed hormone therapy to block their effects on cancer cells.

The research showed that blood taken from women who use birth control pills contained much higher levels of hormones compared to women who don’t.

And, that four out of seven formulations tested were found to quadruple the levels of progestin, a synthetic version of the hormone progesterone.

Another formulation also resulted in 40 per cent higher exposure to ethinyl estradiol, synthetic version of oestrogen.

Despite the findings, the study’s lead author, human evolutionary biologist Beverly Strassmann, stressed that the contraceptive pill has had such a positive effect on the lives of so many women.

But, that it’s also important for companies to design birth control pills in a way that doesn’t contribute to a greater risk of breast cancer.

“Not enough has changed over the generations of these drugs and given how many people take hormonal birth control worldwide — millions — the pharmaceutical industry shouldn’t rest on its laurels,” she said.

Previously commenting on the links between breast cancer and birth control, the NHS states that, “the baseline risk of women of a fertile age developing breast cancer is small,” and that “Unfortunately, there are often no easy answers when weighing up the benefits and risk.”

Cancer Research UK currently advises that as little as one per cent of breast cancers in women are a result of oral contraceptives.

“The protective effects of the pill against womb and ovarian cancers last longer than the increased risks of breast and cervical cancers,” it says.

“Overall, this means that the protective effects outweigh the increased risk of cancer if you look at all women who have taken the pill.”