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Feb 24, 2014 11:38AM
Feb 24, 2014 12:00PM
So many people are misinterpreting and reading more into the results of this study that the study was actually saying.
Firstly, the reason for this latest study is, as follows.
In 1980 a randomised controlled trial of screening mammography and physical examination of breasts in 89,835 women, aged 40 to 59, was initiated in Canada, the Canadian National Breast Screening Study. It was designed to tackle research questions that arose from a review of mammography screening in Canada and the report by the working group to review the US Breast Cancer Detection and Demonstration projects. At that time the only breast screening trial that had reported results was that conducted within the Health Insurance Plan of Greater New York. Benefit from combined mammography and breast physical examination screening was found in women aged 50-64, but not in women aged 40-49. Therefore the Canadian National Breast Screening Study was designed to evaluate the benefit of screening women aged 40-49 compared with usual care and the risk benefit of adding mammography to breast physical examination in women aged 50-59. It was not deemed ethical to include a no screening arm for women aged 50-59.
In addition, it must be remembered that this was a retrospective, observational study; to do otherwise would be deemed medically unethical. So, complication Number 1. The findings are observational only with no ethical way of testing them.
Also, it's not that they were trying to disprove that screening mammograms were of no use, they were trying to determine the risk/benefit of adding mammography to "usual care" in specific age groups. The purpose was to see if adding mammograms to regular breast/health screening resulted in decreased mortality in a community-based setting. This is where complication Number 2 factors in: mammography has improved tremendously during the last thirty years. In 1980, only 50% of mammography images were of satisfactory quality, by 1987, this number had risen to 87% (see: Rational and Irrational Issues in Breast Cancer Screening).
The results of this new study revealed an over-diagnosis rate of about 20% by adding screening mammography to "usual care", meaning that this percentage received unnecessary treatment for breast cancers that may not have become life-threatening for the researched groups. The problem with this result is, they did not separate out the nasty breast cancers from the ones that may never have developed into anything nasty. Why? Because, technically, we have no means of doing that yet. And that's a bit of a grey area that causes such controversy about these findings.
The study did, indeed, find that adding mammography to "usual care" in a community setting for these age groups did not decrease mortality from breast cancer, but - again - this is a grey area because there was no way to separate out the nasty breast cancers from the ones that may never have developed into anything nasty. So, in a way, the point becomes moot. There is no increase in survivability, but there is no way to know who would have survived anyway.
So, while the CNBSS shows that - by adding mammography to "usual care" results in a degree of over-diagnosis of "indolent" breast cancers and doesn't decrease one's mortality from breast cancer in a community setting - it comes nowhere close to establishing that screening mammography is useless or, even, dangerous. What it does is establish that the role of screening mammography needs to be reassessed for women at average risk of breast cancer, but it in no way addresses the issue of screening mammograms for women at high risk (including those with strong family histories, as well as those with personal histories) of breast cancer. Nor does it address the issue of how to identify tumours which may not need treatment from those that do. More research and better imaging techniques need to be developed and that is, really, all this study is stating. And the study continues to imply that - for the 60 and over age group - screening mammograms still play a role in saving lives.
If all radiation - meaning that it doesn't matter what the source is - caused cancer, Leia, then we'd all be dead. We absorb more radiation into our bodies from "natural' sources than we do from medical sources. It's in the air, our soil, our water and our food. It cannot be avoided. We ingest this radiation in our food and water at higher r levels than we would receive from a mammogram. We are, also, born with radiation in our bodies: potassium-40, carbon-14 and lead-210. The following article discusses how much of this radiation is absorbed by people who work at jobs at "high risk" for these exposures (including those in the medical field), so those of us who are not exposed to medical imaging on a daily basis may have a much lower exposure level. Either way, medical procedures involving x-ray and mammograms consist of only a fraction of our radiation exposure.
Stating that screening mammogram are "moronic" and citing one- or two instances when they did not help "save a life" is missing the point entirely. But, I'm finding, so many of those who are vested in furthering their own beliefs simply resort to fear-mongering to make a point or a flashy headline, or to further their own agenda, or product line. The subtleties are lost on them because they only see the surface and not the substance. Plus they want to make a great deal of money from exploiting vulnerable and scared people.
Don't read too much into the articles from questionable sources that claim that mammograms (or x-rays or MRI's of PET scans) put your life in danger. That simply is untrue.
"... good girls never made history ..."