The pill rarely leads to breast cancer. Weight problems, lack of exercise, and not having children are bigger risk factors. (Photo: Shutterstock)

Should I really stop taking the pill to prevent breast cancer?

Stopping taking the pill only removes a very small risk factor. Other changes could have a bigger effect.

Thomas Hoffmann

Published 14 January 2018 - 06:30

Taking the contraceptive pill can increase your risk of breast cancer. This has long been known, but the relationship has now been confirmed by a new study published in the New England Journal of Medicine.

It shows that the contraceptive pill only causes a very small increase in risk of developing breast cancer.

Scientists studied data from 15 to 49 years old girls and women in the national Danish health registers.

In a group of 100,000 women who took the pill, there were 13 more cases of breast cancer (68 cases in total), compared to another group of 100,000 women who did not take the pill (55 cases were observed in this group).

While everyone would like to avoid cancer, the results of the new study are mostly relevant for women over the age of 40, says Professor Niels Kroman, MD, from the University of Copenhagen and the Danish Cancer Society.

“Until 30 years of age the disease is extremely rare. But in general, when you turn 40 you should stop taking the pill, especially if you have other risk factors—first and foremost if there’s breast cancer in the family,” says Kroman, who was not involved in the new study.

The IUS coil is just as dangerous as the pill

For women over 40 who are looking to switch contraception, lead-author Lina Steinrud Mørch from Rigshospitalet, Copenhagen, recommends non-hormonal alternatives such as a hormone free IUD coil (that releases copper instead of hormones) or condoms.

The IUS coil releases progesterone instead, and causes a similar increased risk of breast cancer as the pill, shows the news study. A finding that was not previously so well known.

“It’s quite a small risk in absolute numbers, but there is a risk for women who are otherwise healthy. You should consider using alternatives, such as condoms, when you don’t have a partner, and postpone starting hormonal contraception,” she says.

The study demonstrates an increased risk of breast cancer with prolonged use of hormonal contraceptives. But the risk also subsides if you limit use to no more than five years of continual use.

The pill is not the primary cause of breast cancer in women

Kroman emphasises that even if all women stopped taking the pill, there would still be cases of breast cancer reported.

Each year, around 5,000 women contract the disease in Denmark (along with a few men). The overriding cause is neither smoking, contraceptives nor endocrine disruptors, it is biological, says Kroman.

As soon as women hit sexual maturity, their hormones start affecting undeveloped tissue in their breasts and this increases the risk of breast cancer later in life. However, this tissue only develops fully during pregnancy.

“Breastfeeding and having more pregnancies reduce the risk of breast cancer. If all Danish women had children at the age of 18, and again at 25, then we would halve the number of cases of breast cancer,” says Kroman.

While this information might not be helpful for women today, there are a number of other actions they can take to reduce the risk of breast cancer, such as exercising, reducing alcohol intake, and weight management.

In a 2005 article, Kroman and gynaecologist Øjvind Lidegaard from the University of Copenhagen, who also co-authored the new study, identified the following risk factors for breast cancer:

High alcohol intake
Genetic makeup
Not having children or having just a few children
Women’s age at their first pregnancy
Weight
Lack of exercise

According to their study, there is only a limited effect associated with diet change, quitting smoking, or avoiding hormonal supplements.

For and against the pill

The new study is the largest of its kind and updates and confirms previous research on the pill. It also reveals that the risk of developing breast cancer is largely the same, regardless of the type of hormonal contraceptive method used.

The overall picture of the effect the pill has on women’s bodies is still unclear.

On one hand, previous studies have shown that the pill increases the risk of stroke, depression, and suicide, among young women. Other studies have indicated that the pill increases the risk of brain tumours.

But studies have also shown that the pill not only prevents unwanted pregnancies, it also reduces the risk of other types of cancer. Women who have taken the pill also live longer on average.

But only older forms of the pill have been documented to protect against other types of cancer, says Mørch. ”Although we expect the same benefits of the newer types of HC, this evidence is lacking.”

“You should make sure that you know the woman’s family history in respect to breast cancer, heart disease, and mental health, and inform her of her risks,” says Mørch.

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Read more in the Danish version of this story on Videnskab.dk

Translated by: Catherine Jex