I've had a chance to look at the evidence report issued by the United States Preventive Services Task Force that released the new recommendations for mammography screening earlier this week.
The evidence report is a public document available at:
The report is entitled, Screening for Breast Cancer: Systematic Evidence Review Update for the U. S. Preventive Services Task Force, and was published this month by the AHRQ (the U.S. Agency for Healthcare Research and Quality). Anyone taking issue with the new recommendations should probably read the report before voicing their opinions.
For me, the biggest flaw in the report was the following line, where the task force wrote the limitations of the study:
"Limitations: Studies of older women, digital mammography, and magnetic resonance imaging are lacking."
I've been told that the latest digital mammograms produces superb images, that have diagnostic advantage over the images produced by the older instruments. If this is the case, then the labs that are currently using digital mammography may be doing a better job than the labs that are using the older equipment. More relevant to the task force report, the conclusion based on reviewing data using the old testing equipment may not be applicable for labs using the new equipment.
The problem with task force reviews, is that they're always working with data that lags behind the latest advances in the field. Basically, today's reality may be different from the reality that they reviewed.
It always seems to come back to two issues that I discussed in my blogs this week.
First, are all labs equal? Are there some labs that perform mammographic testing so well that a data review of their patients would show that mammographic screening in the 40-49 age group is justified, FOR THEM.
Second, as a screening test becomes more sensitive, and we start picking up small, early lesions and lesions of no biological consequence, how do we choose a clinically beneficial way of handling the test results?
The answer to the first question may involve using certified reference labs that perform tests at a high technical standard. If you want mammographic screening, why not have it done by highly competent professionals?
The answer to the second question comes down to how we approach the clinically unknown. If we have a test that produces lots of findings of undetermined clinical significance, then it seems ill-advised to throw up our hands and say that women shouldn't take the test because the results may be difficult to interpret. Wouldn't it make more sense to conduct some clinical research and learn something about these subtle lesions? We can't move forward by collecting anecdotal evidence; we need to examine data on hundreds of thousands of cases from the best mammographic labs. Then maybe we can start to design rational clinical trials where we look at how we can best deal with those lesions. I'm sure that among the small lesions found on mammography there will be lots of precancers. It would seem to me that mammographic screening in a young age group will give us the opportunity to develop effective and simple treatments for breast precancers (thus stopping the development of invasive cancer).
- © 2009 Jules J. Berman, Ph.D., M.D.
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