NEJM - Screening Mammography and Breast-Cancer Incidence

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NEJM - Screening Mammography and Breast-Cancer Incidence

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  • Kathy044
    Kathy044 Member Posts: 433
    edited November 2012

    Yet another study, this one using data from the US.

    Effect of Three Decades of Screening Mammography on Breast-Cancer Incidence
    Archie Bleyer, M.D., and H. Gilbert Welch, M.D., M.P.H.
    N Engl J Med 2012; 367:1998-2005November 22, 2012

    "We estimated that in 2008, breast cancer was overdiagnosed in more than 70,000 women; this accounted for 31% of all breast cancers diagnosed."

    http://www.nejm.org/doi/full/10.1056/NEJMoa1206809?query=TOC

    Kathy

  • curveball
    curveball Member Posts: 3,040
    edited November 2012

    I heard about this study on the radio today. I don't see how these doctors can rightly call it "over diagnosis" or "over treatment" until it's possible to distinguish the 31% of cancers which won't progress from those that will. 

  • wallycat
    wallycat Member Posts: 3,227
    edited November 2012

    This is very similar to the question men are asked...do they need the PSA test.  Sadly, since they do not know which of these cancers can lay dormant and which become deadly, most people are smart and go get their mammograms.  Thankfully, now they are saying dense breasts require ultrasound or MRI.  In THAT case, mammos may do little.

  • 1Athena1
    1Athena1 Member Posts: 6,696
    edited November 2012

    The lesson I take from this is that mammography has given people a false sense of comfort but it is missing the mark, and that people are mistakenly equating huge numbers of diagnosed people with success in identification at some level.

    We need to realize ths and redefine what it means to have success in bc treatment. I think success needs to be measured in terms of long-term outcomes (NOT five years), and not in terms of screening and diagnosis. I welcome this study. It poses some uneasy questions, but unless our scientists are willing to face them the lack of real progress in the fight against breast cancer will remain as it is.

    The conclusion of the article should give us all pause: Despite substantial increases in the number of cases of early-stage breast cancer detected, screening mammography has only marginally reduced the rate at which women present with advanced cancer. Although it is not certain which women have been affected, the imbalance suggests that there is substantial overdiagnosis, accounting for nearly a third of all newly diagnosed breast cancers, and that screening is having, at best, only a small effect on the rate of death from breast cancer.

  • curveball
    curveball Member Posts: 3,040
    edited November 2012

    @athena, maybe I am splitting hairs, but in my opinion the study does not reveal over diagnosis of early BC, it reveals under diagnosis of advanced cancers. To me, the use of the term "over diagnosis" implies that women should not be screened and/or women with early cancer revealed by screening should not be treated unless and until the disease advances further. I think the questions that need to be asked are:

    • why has screening not reduced the numbers of women who present with advanced cancer? Are these women who didn't get screened, or did they get screened but the disease was not detected at an earlier stage? Or did they get screened and detected early, but not treated (e.g due to lack of insurance)?
    • were cancers which are first detected at an advanced stage present but missed by screening, or did they actually develop extremely rapidly, between one screening and the next?
    • can other screening methods detect cancers that are missed with current methods? Specifically, is there a way to detect at an early stage the cancers that currently don't present until the disease is advanced?
    • would the cancers which currently present at an advanced stage be more treatable if they were detected early, or are they inherently more aggressive and less affected by treatment? Do the same factors make a cancer both harder to detect and harder to treat?
    • how can early-stage cancers which are "idle" and require only minimal treatment be distinguished from those which need a more aggressive approach to prevent progression and metastasis?
    • what are more effective treatments for advanced-stage breast cancer?

    The article seems to me almost trying to lay a guilt trip on those who get screened and treated for early breast cancer, and that makes me mad. The un-spoken message seems to be, "you who get screened and treated early are using more than your fair share of medical resources and contributing to rising health care costs", and "screening is a waste of money because about 1/3 of the cases detected wouldn't advance, even without treatment". I don't say it's deliberate, but the article also drives a wedge between early & late stage patients. It implies "screening is using up resources that could be directed to finding better treatments for advanced disease".

    What this article fails to say is that nearly a third supposedly over-diagnosed means that more than two-thirds of those screened are appropriately diagnosed & treated, or possibly even under-treated. Until there is a way to distinguish the one who doesn't need treatment from the two who do, screening followed by treatment of all cancers detected is the best we have. Criticizing screening won't help anyone whose cancer isn't detected until late, but it may well harm some of those who are currently being detected and successfully treated as a result of screening.

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