Some contraceptive pills double risk of breast cancer

In In The News by Barbara Jacoby

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Women taking the contraceptive pill are 50 per cent more likely to develop breast cancer with those containing high hormone doses more than doubling the risk, a study has found.

Researchers found women who took pills containing a high dose of hormone oestrogen were more than twice as likely to be diagnosed with breast cancer while other forms of the contraceptive containing low levels of the hormone did not increase cancer risk at all.

The study compared at 1,102 women who were diagnosed with breast cancer between the ages of 20 and 49 with a group of similar unaffected women and looked at their contraceptive history.

Women who had taken the combined Pill in the last year were 50 per cent more likely to have developed cancer compared with those who had never used it or stopped taking it more than a year earlier.

The study looked at the type of combined Pill used and found that the higher the dose of oestrogen it contained, the greater the risk of cancer.

Low dose Pills were not linked with an increased risk of breast cancer but women who took a high dose oestrogen pill were more than twice as likely to have developed cancer.

The findings were published in the journal Cancer Research.

Dr Elisabeth Beaber, a staff scientist in the Public Health Sciences Division of Fred Hutchinson Cancer Research Center in Seattle, said: “Our results suggest that use of contemporary oral contraceptives [birth control pills] in the past year is associated with an increased breast cancer risk relative to never or former oral contraceptive use, and that this risk may vary by oral contraceptive formulation.

“Our results require confirmation and should be interpreted cautiously.

“Breast cancer is rare among young women and there are numerous established health benefits associated with oral contraceptive use that must be considered.

In addition, prior studies suggest that the increased risk associated with recent oral contraceptive use declines after stopping oral contraceptives.”

Dr Caroline Dalton, Senior Policy Officer at Breakthrough Breast Cancer, said: “Previous research in this area has found similar results for higher dose birth control pills in terms of increased breast cancer risk but data from this study is welcome in that it tells us more about the differences between high and low dose options.

“Levels of oestrogen in the combined Pill have decreased over the past 30 years. Whilst the researchers state that these findings require further investigation, we are a little closer to finding out whether or not newer, lower dose pills are associated with the same risk as the higher dose formulations more commonly used in the past.

“However, it is important to note that breast cancer is rare in women under the age of 40, regardless of whether or not they use the contraceptive pill.

“In addition, ten years after coming off the Pill any increased risk will have disappeared leaving the chance of developing breast cancer at around the same level as those who’ve never taken the Pill.

“We’d advise women with any concerns about starting or stopping the Pill to talk through the options with their doctor.”

Sarah Williams, Cancer Research UK’s senior health information officer, said: “Women shouldn’t stop taking the Pill on the basis of this study. It can’t tell us whether newer versions of the Pill affect the risk of breast cancer in a different way from older versions.

“Not only could many of the findings about different types of Pill be down to chance, the study also failed to fully account for things like age, family history of breast cancer, or whether a woman had recently been for breast screening. And the research doesn’t consider whether or for how long women had used the Pill previously.

“The Pill is already known to have effects on several different cancers: breast and cervical cancer risk is raised while a woman is taking it, but goes back down again within 10 years of stopping.

“But the Pill also offers lasting protection against ovarian and womb cancers for decades after women stop using it. On balance the Pill prevents more cases of cancer than it causes.”