Ovarian cancer screening doesn’t work

For many, cancer screening has obvious appeal. Detecting the disease through screening will generally mean an earlier diagnosis, and earlier treatment should, by rights, lead to better outcomes. Well, that the theory anyway. In practice, though, we know that screening is most certainly not as effective as we might imagine.

For example, mammography has been shown to be quite ineffective as a life-saver, and also subjects women to radiation. Many women with suspicious mammograms go on to have further investigations and treatment that are not without risk (and are stressful too). A significant number of women end up being treated for cancer that would not have harmed for killed them anyway. See here, here and here for blog posts about mammography that might cause some women to think twice about the ‘no-brainer’ decision about whether to get a mammogram or not.

Another cancer that might be, theoretically at least, amenable to screening is ovarian cancer. The results of the first assessment of the effects of ovarian cancer screening are in, and they make for uncomfortable reading.

80,000 took part in the trial, and either underwent active screening or usual care over a 13-year period. Screening involved blood testing for ‘cancer antigen 125’ (CA125) as well as ultrasound via the vagina (transvaginal ultrasound).

At the end of the assessment 212 of the screened women had been diagnosed with ovarian cancer, compared to 176 of those who were not screened.

However, death rates from ovarian cancer (as well as overall risk of death) were the same. In other words, screening for ovarian cancer did not save lives.

It’s important to remember, though, that as a result of screening, a lot of women got investigations and treatment that, in the final analysis, did not help them, and may actually have caused them harm. As a result of screening, more than 3000 women ended up with ‘false-positive’ results (tests indicated the presence of ovarian cancer though there was no cancer present).

Over a thousand of these women had unnecessary surgery as a result, of which about 15 per cent had a serious complication in the form of, say, infection, injury to the bowel and deep vein thrombosis (blood clots in the legs that can break off and go to the lungs causing what is known as ‘pulmonary embolism’ and possible death).

The results of this trial mirror, I think, those which have assessed mammography. It’s another example of something in medicine that keeps the wheels of the medical industry churning away and promises a lot, but in reality delivers very little.

9 Responses to Ovarian cancer screening doesn’t work

  1. Michael Allen 8 June 2011 at 10:09 am #

    As you will know, the NHS in the UK offers a self-administered postal service whereby faecal samples are tested for signs of possible colon cancer. Have you written a post about this in the past? (Can’t find it with a quick Google.) Any thoughts on courses of action for anyone who is sent a letter suggesting further investigation?

  2. katydogcrazy 9 June 2011 at 11:57 pm #

    reply to Michael Allen: My suggestion (as an RN and someone with ongoing GI bleeding)is that the person in question should redo the same screening test. It is very inexpensive and completely non-invasive. Great care should be taken with following the directions regarding diet and medication intake during the days before the stool samples are collected (here in Canada we are advised to avoid certain foods, and drugs like ASA, and large amounts of supplemental vitamin C; also to be avoided but not usually listed are various herbs including Ginkgo and St. John’s Wort which may increase bleeding time). Any constipation should be corrected before the sample collections as slight local bleeding (which is utterly meaningless cancer wise)can be caused by passing hard stools, even when there is no perception of discomfort.

    What is wanted is to have the test measure ONLY significant bleeding in the lower bowel and rectum. Such bleeding will be from fissures (not a cancer issue) or polyps (some pre-cancerous, some not) or actual cancer tumours. It is very easy to get false positives on this test (the vitamin C does not cause bleeding but is misinterpreted by the testing chemical combination), iron supplements may skew the result, etc. And bleeding from higher up in the GI tract can be missed as the blood is well digested by the time the stool is passed. So the test REALLY is just a screening measure, and not to be considered diagnostic. That said, if one gets positive (that is evidence of bleeding IS found) results after scrupulous adherence to the precautions for food and drug for the days prior to sample collection, I believe it should be followed up with one’s GP. Here we would be sent for colonoscopy although there would likely be a delay of months to have it done.

    For myself, if I had positive results followed by negative results on repeating the screening test, I would lean toward carefully repeating it every six months.

  3. Michael Allen 10 June 2011 at 10:24 am #

    Many thanks to katydogcrazy. The info should be helpful to anyone who is invited to take this test, which in the UK has, I believe, recently been extended to those over 70.

  4. Daisy 10 June 2011 at 10:56 am #

    My mother died of a rare form of ovarian cancer (PPC). She was told she was suffering from irritable bowel syndrome, and was stage four before anyone took her seriously. I have been told subsequently she would have died anyway, even if she had been diagnosed on day one, but here in France I am assured that early diagnosis and treatment is usually successful. Should someone with my family history seriously avoid screening?

  5. John Briffa 10 June 2011 at 11:12 am #

    Daisy

    Not sure what you mean by ‘seriously avoid’, but the point is that individuals need to be aware of the downside of screening and its general ineffectiveness to make more informed choices about whether to have it or not.

  6. helen 12 June 2011 at 5:39 am #

    Well I find usually if one is looking for something and looks long enough one will eventually find something!!! So I look constantly for signs of my good health and live my life knowing I will be healthy until I decide to leave the planet!! Just live and enjoy your lives, really enjoy your life!! stop constantly being afraid of some disease or other and certainly stop looking for things that are wrong or not in most cases the stress certainly isn’t good for you anyway!! :) smile and laugh a lot – play and do things that you love doing. Just live the life you have NOW.

  7. Daisy 12 June 2011 at 10:13 am #

    Dr. Briffa, Sorry, bad sentence structure. I meant something along the lines of “Avoid? Seriously?”

    Thanks for the kind thoughts, Helen. I do love my life. I’m glad you do too.

    Unhappily, though, I have lost some close family and family and friends to cancer due to a lack of screening, and therefore early diagnosis. Which is hard to be upbeat about. So I think it’s understandable that people like me are reluctant to avoid screening.

  8. Bill 12 June 2011 at 11:13 am #

    An excellent critical analysis of cancer screening by a Dartmouth physician:

    http://www.amazon.com/Should-Be-Tested-Cancer-Maybe/dp/0520248368/ref=sr_1_2?ie=UTF8&qid=1307877012&sr=8-2

    If you take this book to heart, your primary care doctor may not be amused as you may take a lot less of his or her advice about getting screened! He is not against screening, by the way, just believes it has been wildly oversold and can cause more harm than benefit in many cases.

  9. John Briffa 12 June 2011 at 11:28 am #

    Bill

    Thanks for this.

    He is not against screening, by the way, just believes it has been wildly oversold and can cause more harm than benefit in many cases.

    My sentiments, exactly.

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