This 44-Year-Long Study Looked At The Links Between Cancer And Birth Control


A 44-year study found great news for pill users.

Posted on March 25, 2017, 13:01 GMT

Good news for birth
control users: A 44-year-long study found no increased
lifetime cancer risk in women who used the birth control
pill, compared to women who never did.

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The study, published in the American Journal of Obstetrics &
, is the longest-running study on the
health effects of birth control pills.

General practitioners in the UK recruited over 46,000
women in 1968 and 1969 to take part in the study, which
followed them until December 2012. At the time of
recruitment, about half of the women were using combined
oral contraceptives (birth control pills with estrogen
and progestin), while the other half had never used them.

Women who had ever used
birth control pills had a lower risk of several cancers,
including colorectal, endometrial, and ovarian

Plus, the reduced risk of colorectal and ovarian cancer
seemed to persist for many years after stopping
— possibly more than 35 years, noted the study authors.

An increased risk of
breast and cervical cancer was seen in current and recent
birth control users, but those associations disappeared about
five years after stopping the method.

The study found no evidence of an increased risk of either
cancer later in life for women who had used birth control

So even if you’ve been using birth control pills for the
better part of a decade, it’s encouraging to see that this
44-year study didn’t find any long-term consequences
associated with that.

Still a little worried
about that slight increased risk while taking the pill? You
probably don’t need to be.

Toeps / Getty Images

We’ve already known about the slightly elevated risk of
breast cancer while taking birth control pills, which
previous research showed to be
eliminated 10 years after stopping the method.

Dr. Mary Jane Minkin, OB-GYN and clinical professor at
Yale School of Medicine, told BuzzFeed Health that this
slight increased risk most likely means that some cancers
could be more likely to grow and become detectable while
you’re taking hormonal contraception. These cancers
typically take years to develop, says Minkin, but it
makes sense that the presence of hormones may accelerate
that process for some. That said, the fact that the
increased risk goes away after you stop the method means
that it probably isn’t causing new cancers to form in
your body, explained Minkin.

And about that cervical cancer risk, Minkin said it’s
important to remember that many people taking birth
control pills (especially back in the 70s) were not also
using condoms, which could put them at an increased risk
of HPV, which can cause cervical cancer. Another theory is that the hormones in birth
control pills might affect how your body responds to HPV
infection. Regardless, it’s reassuring to see that there
was no long-term association between birth control pills
and cervical cancer.

Finally, keep in mind that the risk of these cancers is
already very low in young people, said Minkin. In the US,
the absolute risk of developing breast
cancer in the next 10 years is 0.06% for a
20-year-old and 0.4% for a 30-year-old. And cervical
cancer occurs most often in women over age

Of course, there are
some limitations to this study. Most obviously: that it
started almost 50 years ago.

The birth control pills most women were using in this study
were very different than the ones we use today. According to
the study, their birth control pills usually contained 50
micrograms of estrogen, while most pills today contain about
20-30 micrograms.

Plus, the mean amount of time these women used birth control
was 3.66 years, while most people stay on it for much longer
than that these days.

The study authors also noted that they didn’t recruit women
with chronic diseases for this study, so it’s possible they
had a healthier-than-average cohort.

All that said, it’s the longest-running study on the
long-term effects of birth control, and that’s pretty damn

Essentially, this new
data confirms a lot of what we already knew about these
associations, while also reassuring us that birth control
doesn’t contribute to an increased lifetime risk of cancer.
Instead, it might actually have a long-term protective

“My takeaway from this is that it’s very reassuring,”
said Minkin.

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