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Monday’s medical myth: the pill increases your risk of cancer

Millions of women around the world have used the combined oestrogen and progestogen oral contraceptive pill to protect themselves from pregnancy for more than fifty years. The overall risk of reproductive-aged…

If you’re at low risk of cancer, the pill is unlikely to place you at higher risk. Flickr/BeppieK

Millions of women around the world have used the combined oestrogen and progestogen oral contraceptive pill to protect themselves from pregnancy for more than fifty years. The overall risk of reproductive-aged women developing cancer is low, but debate continues as to whether using the pill could increase this risk.

In fact, fear of cancer has been identified as a major reason for women not using reliable contraceptive methods.

Women’s risk of developing cancer depends on a large number of factors, including family history, cigarette smoking, weight, diet and physical activity and whether you’ve had children (and at what age), among other things.

The pill works by effectively switching off a woman’s natural production of ovarian oestrogen and progesterone and replacing this with a synthetic version of both hormones.

A change in cancer risk associated with the pill could potentially be related to the synthetic hormones within the pill. But it could also be due to the fact that the ovaries have been “shut down” for a period of time. It’s likely a range of determinants are involved.

Researchers' attempts to assess any link between the pill and cancer are complicated by a number of factors.

Firstly, women have access to a wide variety of contraceptive pills, which have different oestrogen and progestogen components, doses of hormones, and schedules of delivery. Some pills have a stable dose; others vary throughout the cycle. The original contraceptive pill also had much higher doses of hormones than the modern pill. So there’s no standard “pill” researchers can use to generalise cancer risk.

Secondly, many women have taken a variety of contraceptive pills throughout their lifetime. This makes recalling the type of pill – and the duration of the prescription – difficult. And this creates some uncertainties in the research.

Women’s risk of developing cancer depends on a large number of factors, including family history. lululemon athletica

So what does the research say?

Despite concerns that the pill increases the risk of cancer, systematic studies have found the incidence of some cancers is actually reduced in women taking the pill.

Numerous studies confirm that taking the pill is associated with a reduced risk of ovarian cancer. This protective effect is greater the longer one uses the pill, and extends for several years after use is ceased.

Multiple studies have also found a 50% reduction in the risk of endometrial cancer for women taking the pill, which is still apparent for ten to 20 years after use has ceased.

A study of more than 300,000 European women reported a decrease in colorectal cancer in women who had ever used the pill, but the effect was only significant amongst postmenopausal women.

The studies for breast cancer and the pill report conflicting findings. Most researchers have concluded there is no significant link between previous or current use of the pill and breast cancer risk. But some studies suggest a slightly increased risk for current pill users, which disappears five to ten years after a woman stops taking the pill.

Using an oral contraceptive for more than five years has also been linked to an increased incidence of cervical cancer. Again, this additional risk decreases with time after a woman stops taking the pill and has disappeared within ten years of cessation.

So, what does this all mean for women taking the pill?

Be reassured that if you’re at low risk of cancer, the pill is unlikely to place you at higher risk – and may even protect you against some cancers after your reproductive years end.

But every woman’s risk profile is different. When you discuss your contraceptive choices with your doctor, be sure to ask about your specific risks and benefits associated with the pill.

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14 Comments sorted by

  1. Tim Crowe

    Associate Professor in Nutrition at Deakin University

    A very well written, evidence-based article and up-to-date summary of the research and consensus views in this area.

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  2. Tom Hennessy

    Retired

    The increased cancer link may be the fact contraception , in many cases , causes a partial or complete loss of menses.
    The lack of menses causes the body to begin to load iron which would normally be lost through the loss of blood in the menses , as evidenced by loss of menses in those women who have a hysterectomy.
    "Women have lower iron levels than men, both in the periphery and in the brain, particularly in white matter (WM), possibly due to iron loss through menstruation"
    "Hysterectomy is associated with increased brain ferritin iron"
    http://www.ncbi.nlm.nih.gov/pubmed/21925770

    Increased iron has been very closely related to cancer.
    "The role of iron in cancer"
    http://www.ncbi.nlm.nih.gov/pubmed/8664805

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    1. Sue Ieraci

      Public hospital clinician

      In reply to Tom Hennessy

      So, Tom Hennessy, does your research show an increased cancer risk in women who have many children compared with those who have none? And what about elite athletes who don't menstruate?

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    2. Tom Hennessy

      Retired

      In reply to Sue Ieraci

      Since you ask about women who have many children , I will assume you have no idea women lose their iron to their unborn children.

      Women athletes don't get cancer ?

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    3. Sue Ieraci

      Public hospital clinician

      In reply to Tom Hennessy

      So women are anaemic if they have children or menstruate, and get cancer if they don't? It's a wonder there are any women left.

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    4. Tom Hennessy

      Retired

      In reply to Sue Ieraci

      Quote: It's a wonder there are any women left

      Answer: Isn't it though , with all the world believing women are literally bleeding to death due to their menses.
      Everyone being told and believing we cannot even eat enough food to get the iron we need.
      We are BORN with a set amount of iron which we would normally just 'top up' as we lose iron in our perspiration or menses.
      This same iron our mother gives us at birth is still circulating in our bodies and will still be when we expire.
      It is…

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    5. Sue Ieraci

      Public hospital clinician

      In reply to Tom Hennessy

      So many whacky assertions there, Tom Hennessy. Let's take one at a time.

      "Everyone being told and believing we cannot even eat enough food to get the iron we need." Everyone being told that? And believing it? What evidence do you have for that?

      " as we lose iron in our perspiration " truly? Do we all sweat blood?

      "giving iron to a pregnant woman harms the unborn child." How and what harm?

      "The majority of morning sickness is cured by ceasing the ingestion of the iron." Nope. Nausea in…

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    6. Tom Hennessy

      Retired

      In reply to Sue Ieraci

      Quote: "Everyone being told and believing we cannot even eat enough food to get the iron we need." Everyone being told that? And believing it? What evidence do you have for that?

      Answer: "the meat diets nor the vegetarian diets fulfilled the estimated daily requirements of absorbed iron in spite of a meat intake of 180 g/d in the meat diets"

      Quote: as we lose iron in our perspiration " truly? Do we all sweat blood?

      Answer: We sweat out iron , which is why they put iron chelators in sunscreen…

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    7. Sue Ieraci

      Public hospital clinician

      In reply to Tom Hennessy

      Not surprisingly, Tom Hennessy, your references do not support your assertions.

      Chintzy indeed!

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    8. Tom Hennessy

      Retired

      In reply to Sue Ieraci

      Each and every one of my assertations is backed up by provided references. Your denial that the evidence IS provided AND jibes with everything I said borders on medical malfeasance .

      JUST like before .. high iron = high diabetes

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  3. Antonio Manuel Santos Cristovao

    logged in via Facebook

    I never forget the remark of a vetrenarian about dog health problems. Yes if se takes pill the change of cancer is very likely and usual happen plenty.

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  4. Holly Luland

    Undergraduate in Conservation Biology (3rd)

    I have wondered about whether this possible myth has generated as so far a statistically confounded one.

    That is that there is may be a hidden influencing variable -C or even D - may be contributing to the correlation (of course which is not causation) of A and B.

    My skeptisim for a warning given by a GP once about the risk of pills leading to breast cancer was this, women would get regular prescriptions at their GPs received frequent professional breast examinations and related assessments. I can't speak for the health of the majority of women who take the pill, but if I didn't personally require the pill I wouldn't be visiting a doctor outside of a pap-smear.

    It may be possible I was hypothesising that more women who are regularly checked are picked up for breast cancer than those not taking the pill and not going in for regular examinations.

    Of course my assumption is that many women who take the pill would otherwise rarely visit a doctor.

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