It's been pretty clear for years that screening healthy women without family history for breast cancer, even over 50, causes more harm than it cures. (Past posts on this topic are here, here, and here.)
But a recent study, written up in the Los Angeles Times, may finally get the message across: More than half of new breast cancers diagnosed in the U.S. are not dangerous. But the treatment that comes after they're discovered are dangerous, or at least expensive, painful, worrisome, and invasive.
Breast cancer is not as simple as doctors thought 40 years ago, but somehow treatment and screening guidelines are stuck in the past. "One woman’s tumor might reach 2 centimeters and then stop growing for many years. Another’s might progress from undetectable to a dangerous 5 centimeters in a matter of months."
In fact, the majority of abnormalities picked up by mammogram will never become deadly if left in place.
The study looked at the most important outcome: does early screening head off the incidence of large tumors, and (most importantly) prevent death?
[They] tallied the number of breast cancer findings and the size of the tumors found in women over 40 who were diagnosed with breast cancer between 1975 and 1979, before screening mammography became widely available.And the number of harmless tumors found went up over time, as mammography's resolution improved:
They compared those figures with breast cancer findings between 2000 and 2002, when screening was widespread.
For both groups, they tracked how women were treated and whether they were still alive 10 years after diagnosis.
The team observed that as more women got routine mammograms, more breast cancers were diagnosed. The additional cancers tended to be smaller, or to be confined to spaces, such as milk ducts, where they had not invaded normal tissue.
If catching tumors while they were still small were a way of nipping large, aggressive tumors in the bud, then widespread screening should have reduced the number of large tumors discovered on mammograms. But the rate at which large and aggressive tumors were found remained “essentially unchanged” between 1975 and 2010, the researchers found.
while lumps smaller than 2 centimeters represented 37% of mammogram-detected abnormalities in the early years of the study, they represented 67% of a much larger pool by 2010.As I wrote in one of my earlier posts on this topic, our brains leave us vulnerable to something called the casino effect:
Just as we only hear about the people who clean up on the slots or win the lottery -- and never about all the money millions of people waste on those pursuits -- so do we hear from individuals who had a mammogram at 40 that caught breast cancer, or who had a stress test for no symptomatic reason that found heart blockages. Sure, those unlikely events happen, but you never hear about the vastly larger group of people whose test found nothing, or even worse, who were harmed by the test, follow-up tests, and unnecessary procedures.I hope this new research finally changes the guidelines for breast cancer screening. If they change, no one will notice the results, but tens of thousands of women will live better lives each year because they'll be saved from unnecessary treatment.