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New Studies for an Old Story: Mammography Screening Isn't Saving Lives

We need to refocus our resources and attention on the two things that really matter: (1) stopping men and women from getting breast cancer in the first place -- primary prevention; and (2) preventing metastasis if they do.
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Woman doing breast self exam
Woman doing breast self exam

It was not possible to look at or listen to any form of media over the past few days without being inundated by new claims about breast cancer. What sense can we make of the news that treating stage 0 breast cancer doesn't save lives? How tired are we all of numbers and statistics being thrown at us about mammography? Women are bombarded with so much information and misinformation that it's not surprising they usually respond only to the simple messages like "Early detection saves lives." Because the actual message: "Mammography screening is not reducing deaths from breast cancer as we expected, the harms of mammography for healthy women probably outweigh the benefits and finding and treating cancer early may not make a difference " are much too scary and counter-intuitive. But that is what the evidence tells us.

Two recent studies taken together further reinforce that screening for breast cancer does not result in a reduction in death from breast cancer. They also confirm that of the tumors mammography finds, about one fifth is "precancer" known as ductal carcinoma in situ (DCIS),also called "stage 0" breast cancer. Treating DCIS as we currently do with surgery and radiation does not reduce mortality. These studies provide more evidence that we are wrong to insist on population screening of healthy women. And that we all spend way too much time focusing on the wrong issues in breast cancer.

Both studies looked at healthy women. The screening study looked at women who had not been diagnosed with breast cancer (Harding, JAMA, July 6, 2015). The treatment study looked at women with DCIS, considered to be a "pre cancerous condition" which is abnormal cells that remain in the duct and have not invaded breast tissue and most of which was found by mammography (Narod, JAMA, August 20, 2015). If the cells have invaded breast tissue, that is referred to as invasive breast cancer, not DCIS. And that is different from metastatic breast cancer which is breast cancer that has spread from the breast to other organs. That is the breast cancer that is deadly.

It is important to know that women who get a diagnosis of DCIS often are treated in the same way as women who are diagnosed with invasive cancer - they have surgery to remove the DCIS (called breast conserving surgery or lumpectomy) and then radiation therapy. Or they may remove their breast completely, sometimes both of them, all in the hopes that the DCIS will not spread to become invasive breast cancer, which few do, and then metastatic cancer, which even fewer do. While these treatments for DCIS are common, there has been no clinical trial that proved that treatment for DCIS would save lives. It was simply assumed that would be the case.

The Narod study shows that regardless of what kind of treatment women with DCIS got, after 20 years the percent of women who died of breast cancer was the same as that of the general population. It also appears that a very small percentage of the DCIS lesions can be lethal - and we need to better understand if that is in fact the case and then how to treat those cases. The risk of death from DCIS is very low for all subsets of women, and within that low risk, this study indicates that women under 35 (1% of the DCIS population) and black women have a higher risk than white women. But no treatment that we use now changes the outcome.

This is reinforced by the screening study, where researchers looked at data from the year 2000 for 16 million women 40 or older, to understand how effective screening mammograms are in detecting larger tumors and reducing the death rate from breast cancer. They found that 53,207 of the women had been diagnosed with breast cancer that year. These women were then followed for 10 years. Not surprisingly, the higher proportion of the population that was screened, the higher the incidence of breast cancer But here's what's important - there was no link between more women getting screened and fewer women dying of breast cancer.

Simply stated, screening women for breast cancer did not reduce their risk of death from breast cancer. All it did was increase the diagnosis of small cancers and DCIS. And the treatment for DCIS, removing a breast, or having breast conserving surgery with radiation, does not reduce your risk of death. Among its many limitations, mammography screening detects a non cancer, DCIS, that pushes women to treatments that don't change their risk of dying. This is what is meant by over diagnosis and over treatment.

Shouldn't we then ask ourselves, what is the benefit of mammography screening? My answer is, "Beats me."

Let me throw yet more numbers and facts at you: mammography screening is a $7.6 billion dollar industry. The detection of metastatic breast cancer (the lethal kind) at diagnosis has not changed since 1975. There are old trials (more than 25 years old) that indicated there was a reduction in mortality, but the newer studies looked at data from more modern mammography, with new treatments, and how mammography works in practice, rather than a clinical trial.

Here is another number: 846,587 -- the number of women globally who, at our current rate of progress, will die of breast cancer in 2035, up from 522,000 in 2012. It seems pretty clear we're moving in the wrong direction, focusing on the wrong issues. Rather than discuss those troubling facts, the breast cancer conversation continues to be about mammography screening for more and younger women and treatments that have been proven not to save lives. Isn't it time to finally change that conversation?

We need to refocus our resources and attention on the two things that really matter: (1) stopping men and women from getting breast cancer in the first place - primary prevention; and (2) preventing metastasis if they do. That is why the National Breast Cancer Coalition has set a deadline to know how to end breast cancer, by January 2020. And we have brought together researchers and advocates from around the world, to focus on solving those two big questions in breast cancer, with a sense of urgency and a realistic plan of action.

There is a need to change the conversation. There is a need to take action. To focus on the right issues and to end breast cancer. Join NBCC's Deadline 2020 campaign and let's turn this around and move in the right direction.