Would you avoid mammography because of this man?
December 11, 2015 11:25 PM   Subscribe

My parents, senior citizens, have become convinced, after reading a study by the prestigious-seeming Cochrane Institute, and the campaigns of its leader Dr. Peter Gotzsche, that mammography causes more harm than good and should be avoided, not just for screening but for diagnosing any potential lump. It has them afraid of radiation, and convinced there is a growing realization that mammography is too dangerous. Is it right to draw this conclusion from this study, and what does it all mean?
posted by anonymous to Health & Fitness (7 answers total) 6 users marked this as a favorite
 
There is nothing in that Cochrane review about the dangers of radiation, though radiation does, of course, carry its own risks. Additionally, the focus of this review was specifically about the benefits of screening, not use of mammography for assessing already-found lumps. Your parents are extrapolated too much from this research. FYI the Cochrane Collaboration is not "prestigious-seeming"; it is the gold standard for evidence based research.

Cochrane collaborations have indeed thrown out some counter-intuitive results (a similar result to this was produced around prostate screening), however, that is science and medicine for you. They aren't flawless, there has been controversy around many of their results from those who disagree, often based on the studies that Cochrane excludes from review because the methodology was deemed flawed. But I'd back up a Cochrane pretty much every time over a single study. The idea that recommended medical practices change and evolve over time is not outlandish; this is how science and medicine work. We used to do a lot of crazy unnecessary medical stuff we don't do any more.

One thing, though, to note about Cochrane collaborations; they are built around what's best at a population level, not an individual level. It's impossible to say whether regular mammographies would help your mother, even save her life, or actively harm her - or neither (the most likely outcome). The summary of this particular review is that an expensive to run and not especially well-loved procedure, in total, doesn't add any real benefit, as the risks of the surgeries you might get (and the probability it doesn't catch any cancers) outweigh the benefits. This doesn't mean mammography hasn't and doesn't save lives, it has and does. It means that in total, it causes more per say 100 000 people than good.

Do remember that no person is the average person. If you have a family history of breast cancer, or other risk factors, mammography may still be the right choice for you.
posted by smoke at 11:47 PM on December 11, 2015 [22 favorites]


This is a great question. Here is the leaflet that Cochrane provides in plain language for people interested in interpreting the results. Cochrane is a solid non-profit institute that is highly respected in the medical field. They conduct rigorous, evidence-based research that is considered to be the "gold standard" of evidence because they're comparing results from the best type of study (randomized clinical trials) with one another in what is called a meta-analysis. Cochrane is where evidence-based practitioners are (hopefully) going first when they look for information about how to care for you or your loved ones (actually, they often go to UpToDate, which in turn reports information from Cochrane and other sources, but I'm getting off track.)

It's important to note that "screening with mammography uses X-ray imaging to find breast cancer before a lump can be felt," and these results are presented based on "seven trials that involved 600,000 women in the age range 39 to 74 years who were randomly assigned to receive screening mammograms or not."

In this review, they are specifically only looking at randomized clinical trials where the participants all are "women without previously diagnosed breast cancer," who are properly randomized into two groups: one experimental group, screening with mammography; and one control group, no screening with mammography. However, it is vital to note that, as they say in the review: "In all trials, women in the control groups were offered usual care. This included mammography on indication, that is for suspected malignancy, with the probable exceptions of the New York trial and the first five years of the Two-County trial."

This directly counters the idea that existing lumps are not an issue that may necessitate a mammogram.

Also note that the New York trial and the other trial they mention were both suboptimally randomized and the methods as reported were not sufficient to explain how subjects were assigned, which is why they are specifically called out above. As they explain in their discussion, "The decision to embark on the screening programmes was made mainly because of the positive results in the New York and Two-County trials." Since these two trials were not randomized optimally, the fact that they influenced policy and caused the initiation of widespread mammography screenings is interesting, to say the least.

Suffice it to say, though, this study does not provide evidence about existing lumps. It provides evidence about routine universal screenings. As they explain in their conclusion:
We believe that the time has come to re-assess whether universal mammography screening should be recommended for any age group. Declining rates of breast cancer mortality are mainly due to improved treatments and breast cancer awareness, and therefore we are uncertain as to the benefits of screening today. Overdiagnosis has human costs and increases mastectomies and deaths. The chance that a woman will benefit from attending screening is small at best, and - if based on the randomised trials - ten times smaller than the risk that she may experience serious harm in terms of overdiagnosis.
So, yes, universal screening mammography: probably not necessary at this point. For people with risk factors, though, it is likely different. We don't have the evidence right now and that might be really hard evidence to get. Your parents should talk to the doctor if there's a lump.

Finally, there are two harms that arise from screening all women. First, some women get treatment when they don't actually have cancer (10 in 2,000 over ten years). A great deal more women experience psychological harm from the stress of a false alarm (200 in 2,000 over ten years). In contrast, 1 in 2,000 women over ten years will benefit and will get needed treatment for breast cancer after a routine screening. However, there are many factors that can help mitigate potential psychological distress: a good understanding of the likelihood of experiencing a false alarm, existing personality, self-care, having a strong relationship with the doctor, etc. Radiation is not discussed as a harm in this review. The danger is largely psychological. That doesn't make it not real, but it changes the equation a bit, because the harm is not inevitable but is contextual.

Take care.
posted by sockermom at 12:57 AM on December 12, 2015 [9 favorites]


This doesn't answer your question but my wife was told by her mother's oncologist to start having mammograms at 34 years old (10 years before her mother's age of diagnosis)... When she went to her "frauenartzin" here in Germany, she did an ultrasound of the breasts. Perhaps that is part of a shift in detection practices?
posted by flink at 3:39 AM on December 12, 2015 [1 favorite]


your parents are confused. the cochrane study is only about the effectiveness of randomized screening (using mammographies to test people at random, when they have no lumps).

mammographies are still considered useful for diagnosing cancer when you do have a lump.

this is what other posts are saying too - i'm just trying to be as clear as possible.
posted by andrewcooke at 3:44 AM on December 12, 2015 [1 favorite]


The dose of radiation in a mammogram study is not high.

"Mammography exposes people to 0.4 mSv, while the extra dose from spending 2 days in Denver is 0.006 mSv, the dose from the airplane flight is 0.04 mSv, the average annual dose from food is 0.3 mSv, the average yearly background dose is 3.1mSv, and the limit for a radiation worker per year is 50 mSv."

In other words, unless they are avoiding plane flights and living at altitude as well (admittedly it would take something like 120 days in Denver to equal a mammogram's worth of radiation), their attitude towards radiation exposure may not be consistent.

More information on radiation risks can be found here. The risk for mammography is classified as "Very Low" (a step above "Negligible").

This article from the NYT gives a more balanced view.
posted by treehorn+bunny at 6:34 AM on December 12, 2015 [3 favorites]


I would keep in mind that these recommendations are related to "universal" best practices. That is, what makes good policy and practice recommendations in a broad sense.

(I haven't read the full study, however.)

Your individual decision about mammography may or may not be in line with those guidelines.

I was in my early 40s with no risk factors when a mammogram found a stage 1 tumor well before I felt a lump. I feel like "saving lives" is maybe not the only metric to use. Finding the tumor early meant, in my case, that I only had to have a lumpectomy procedure, not a mastectomy, and radiation treatments only (no chemo). This won't show up on a "lives saved" measure, but certainly made a difference to me and my quality of life.

I'm obviously glad I had the screening mammogram.
posted by pantarei70 at 6:39 AM on December 12, 2015 [5 favorites]


She did an ultrasound of the breasts. Perhaps that is part of a shift in detection practices?
It may indeed be a shift in detection practice, but it's also not evidence-based, according to another recently published Cochrane review: "Presently, there is no methodologically sound evidence available justifying the routine use of ultrasonography as an adjunct screening tool in women at average risk for breast cancer" [1].

Also, with regards to the metrics used in the review that is the focus of this question, mortality was not the only outcome measure assessed. Surgical procedures were also addressed, and it was found that "significantly more breast operations (mastectomies plus lumpectomies) were performed in the study groups than in the control groups." The same was true of radiography. That is to say that overdiagnosis leads to unnecessary surgery in the screening groups, and the ramifications of this are serious in that about half of the women who have surgery report chronic pain - "equally common among those who had had breast-conserving surgery as among those with a mastectomy, and pain was more common when the women had had radiotherapy."

All this said, mammography screening is something that your doctor should offer you if you desire it, particularly if you are in a risk group (and in fact screening recommendations are different for women in those risk groups), but that statistically speaking on a population level this practice causes more harm than good.

[1] Gartlehner G, Thaler K, Chapman A, Kaminski-Hartenthaler A, Berzaczy D, Van Noord MG, Helbich TH. Mammography in combination with breast ultrasonography versus mammography for breast cancer screening in women at average risk. Cochrane Database of Systematic Reviews 2013, Issue 4. Art. No.: CD009632. DOI: 10.1002/14651858.CD009632.pub2.
posted by sockermom at 10:18 AM on December 12, 2015


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