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breast health, cancer, preventative health, Uncategorized

Does digital mammography really save lives or it is pink Kool-Aid?

There has been a lot back and forth over the mammography study in the BMJ. Excellent or flawed? The beginning of the end of screening mammography or an article to be discarded?

Miller et. al.’s study has further opened (perhaps blew the lid off?) the can of worms surrounding screening mammography and the pro-mammography contingent (mostly radiologists and cancer societies) are out with their ray guns blazing. They claim that it is nothing short of preposterous to question the validity of screening mammography (although that’s what science is, questioning). They say that the BMJ study involves 1980s technology (it does) and we can’t make 2014 guidelines based on equipment that is no longer in use (fair). They also counter that there are lots of good studies to support screening mammography (we’ll get to that in a bit).

Not to be flippant, but comparing other technology gives us an idea about how much mammography might have changed for the better. For example, in the 1980s cell phones (for the lucky few who could afford them) were so large they had to carried around in bags and you had to scream because they were just one generation removed from two tin cans and a string. Today, I deposited a check in my bank using my cell phone without leaving my house. The argument that 2014 technology might be able to do something more should be addressed. 

So, I toddled on over to PubMed and typed in digital mammography mortality. This seemed the most logical search term as the question that we all really want answered is, “Will I live longer if I have regular screening mammograms?” I don’t want trials that tell me the size of a tumor that can be found digitally versus film. I don’t want an opinion piece. I want a clinical  trial that tells me digital mammograms saves lives, because the BMJ study by Miller et. al. is a randomized clinical trial, so you need the same grade of medical evidence to bolster a counter argument. This is research rock-paper-scissors-dynamite, where a randomized controlled trial is dynamite and trumps everything else. You can only fight dynamite with dynamite.

There was ONE CLINICAL TRIAL. And it wasn’t even a general screening study, it was a screening high risk women study. I grabbed a screen shot I was so dumbfounded…

mammography

Maybe I did the search wrong (although what other search engine terms would you use if you wanted to know if digital mammography saves lives?).

I turned to the Cochrane Collaborative for help. People who truly know how to massage a search engine. A 2013 review found 8 clinical trials, but only 7 were of quality to be included. SEVEN. Let’s put this in perspective. We have massive screening programs in North America and there are only seven worthy studies for analysis? The way the American College of Radiology was frothing at the mouth I foolishly assumed there must be hundreds of randomized studies proving that digital mammography is super awesome at saving lives.

Here is a summary from the results section:

“Eight eligible trials were identified. We excluded a trial because the randomisation had failed to produce comparable groups.The eligible trials included 600,000 women in the analyses in the age range 39 to 74 years. Three trials with adequate randomisation did not show a statistically significant reduction in breast cancer mortality at 13 years (relative risk (RR) 0.90, 95% confidence interval (CI) 0.79 to 1.02); four trials with suboptimal randomisation showed a significant reduction in breast cancer mortality with an RR of 0.75 (95% CI 0.67 to 0.83). The RR for all seven trials combined was 0.81 (95% CI 0.74 to 0.87). We found that breast cancer mortality was an unreliable outcome that was biased in favour of screening, mainly because of differential misclassification of cause of death. The trials with adequate randomisation did not find an effect of screening on total cancer mortality, including breast cancer, after 10 years (RR 1.02, 95% CI 0.95 to 1.10) or on all-cause mortality after 13 years (RR 0.99, 95% CI 0.95 to 1.03).”

My conclusion? If the literature concerning digital mammography (the new, better mammography that wasn’t in the BMJ study) was so robust studies like the CNBSS would barely get the time of day in The Journal of Medical Obscurata. No one would care about a study on old equipment if studies on the newer equipment existed and truly showed a benefit. Honestly, it’s a little crude for the American College of Radiology and the American Cancer Society to bemoan a study for older technology when the proof that the newer technology is so great at saving lives seems rather, ahem, sparse.

Screening mammography makes money for radiologists and the companies that make the equipment. It drives a lot of Big Cancer’s fund raising and fuels a lot of the big pink Komen machine, but it doesn’t seem to me that anyone have proven with high quality randomized trials that modern, digital mammography actually saves lives.

We can’t take modern mammography on faith, we have to question until there is proof. That is science and the detractors of the BMJ study should take note.  

 

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Discussion

5 thoughts on “Does digital mammography really save lives or it is pink Kool-Aid?

  1. Thanks for asking hard questions, doing the digging, and encouraging the conversation.

    Posted by Amanda howell | February 15, 2014, 11:59 am
  2. As a med student in the late 1980′s I took a rotation thru radiology. I remember having a discussion about mammography where I said I was reluctant to radiate my breasts yearly from age 40 on and wouldn’t that increase my risk of GETTING cancer from the radiation?….the radiologist agreed that a certain percentage of cancers found would have been caused from the yearly mammograms. Of course, I have no family history, but I don’t test yearly…usually every other. And if there is a non-radiation test, I’d do that instead. If we radiated some guys prostate yearly to screen for cancer, you bet they’d find another way to screen. Maybe we should work on getting Atrazine and other herbicides that have estrogen-like properties out of our water supply.

    Posted by Catharine Crockett | February 15, 2014, 7:09 pm
  3. I may be a bit out of date here. In the UK, there were ‘volumes’ of mammograms that radiologists were supposed to read to maintain their expertise. Sometimes mammograms were double read in an effort towards quality control. As far as I know, only mammograms were ever routinely double read; yet so much of radiology is ‘operator dependent’.

    Is there double reading in the US and Canada? If so, are there two fees?

    Posted by korhomme | February 16, 2014, 2:24 pm
  4. While digital mammography is not significantly better than high quality film screen mammography in most patients, there is a world of difference between poor quality film screen mammography and high quality film screen mammography. You could look to the difference in results of the CNBSS and the Swedish two county trial for demonstration of the differences in both the quality of the mammograms and in the training of the interpreters. How else could you possibly explain the vastly different results of these two large RCTs examining the value of screening mammography?

    RCTs to detect differences in breast cancer death rates among different types of screening require such large populations and long term follow up that they are too expensive to undertake.

    Posted by Denise Chough MD | February 16, 2014, 10:12 pm
  5. Your screen shot doesn’t actually show the punchline of the British study, which was that after screen-diagnosing a bunch of “cancers” (27% of which were DCIS) in the participants, they “estimated” and “predicted” based on tumor size and the like (with no acknowledgement of overdiagnosis) that this would result in a ludicrously high 40% reduction in mortality rate – compared to that reported in another study that also apparently did not report real death rates, but only predicted numbers pulled out of someone’s … hat. And then they announced that they had proven that annual mammography in this group was “clinically effective in reducing breast cancer mortality”! It’s this kind of infuriating scientific scammery, as much as the negative trials, that convinces me never to have another mammogram without a specific reason.

    Posted by jane | February 24, 2014, 3:59 pm

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