Breast Cancer Can Grow and Spread for Decades Before “Early” Detection

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“Early” detection is actually really late. Without mammograms, breast cancer may not be caught for an average of 22.8 years. With mammograms, though, breast cancer may only grow and spread for…21.4 years.

Critics of breast cancer screening claim that, on a population scale, mammograms have never been shown to actually prolong women’s lives on average. But, as you can see at 0:16 in my video Why Mammograms Don’t Appear to Save Lives, there was a clear drop in breast cancer mortality in both the UK and Denmark right when routine mammograms were introduced.

That didn’t appear to be the case in Switzerland, though, where breast cancer mortality had been declining for years before routine mammograms were introduced, so let’s go back and explore what happened in the UK. “It is tempting to conclude that breast screening was causal”—that is, caused the drop in mortality—but it’s a little suspicious that the drop happened immediately. You’d expect it to take a few years to manifest.

What’s more, if you split up the UK data by age group, the whole thing falls apart. At 0:54 in my video, I show a graph that illustrates how the numbers play out—rates of breast cancer mortality by age group over the years. Women in the 50 to 64 age group were the only ones who started screening around the same time, but there were mortality drops in other age groups of women who were not getting mammograms. This was true for the Denmark data as well. They had the same drop in breast cancer mortality with or without screening. What’s going on? 

As you can see at 1:22 in my video, the US data are similar to the UK’s. The United States experienced a beautiful drop in breast cancer mortality right when mass mammograms were introduced around 1990. We saw an even more dramatic drop, however, among women getting less screening, and an even greater drop in breast cancer mortality among women not getting mammograms at all. “In other words, there was a larger relative reduction in mortality among women who were not exposed to screening mammography than among those who were exposed.” What happened? The decrease in mortality “must largely be the result of improved treatment, not screening.” 

Breast cancer mortality started dropping all around the world at the same time, regardless of when mammogram screening started, as you can see at 1:59 in my video. There was “no relation at all between start of screening and the reduction in breast cancer mortality.” “The declines…are more likely explained by the introduction of tamoxifen,” an estrogen-blocking drug. As you can see at 2:15 in my video, breast cancer death rates clearly plummeted in the United States after the Food and Drug Administration approved tamoxifen in 1990.

This doesn’t mean breast cancer screening isn’t playing a role, though. In fact, randomized controlled trials have shown that routine mammograms may reduce breast cancer mortality by 20 percent. Now, that 20 percent drop represents the change from about five in a thousand women dying from breast cancer without screening during that time down to four in a thousand women dying with screening. So, the risk of dying for women who are invited for routine screening is practically the same as the risk of dying for women who are not getting mammograms. What’s more, this is assuming mammograms don’t increase deaths from other causes. In fact, “[i]f we take into account the cardiac and lung cancer deaths caused by radiotherapy,” the radiation treatments given to women who are overdiagnosed with pseudo disease and unnecessarily treated for cancer, thanks to mammography, “there appears to be no mortality benefit.”

Why aren’t mammograms more effective? It seems so simple. Just catch the disease early, right? It turns out that by the time breast cancer is caught by mammograms, it may have already been growing for decades. “It is therefore misleading to say that cancers are caught ‘early’ with screening. They are caught very late…” Without mammograms, breast cancer may not be caught for 22.8 years. With mammograms, however, breast cancer may grow and spread for 21.4 years. It’s not surprising that mammograms don’t do a better job at preventing breast cancer deaths since the cancer can spread before you can even cut it out. Concerns have even been raised that the trauma from surgery may accelerate the growth of any cancer left behind, which may would help explain why there isn’t more benefit to screening. 

Regardless, nine out of ten women may still be in the dark, “overestimating the mortality reduction from mammography screening by at least one order of magnitude,” by ten-fold or more. About the same percentage of men thought similarly about prostate cancer screening, vastly overestimating the benefits or simply not knowing. Only 1.5 percent of women surveyed were in the ballpark, choosing “the best estimate for reduction in mortality due to breast cancer screening.” Ironically, those who reported “frequent consulting of physicians” and reading health pamphlets did even worse, overestimating the benefits of screening programs even more. 

Decades ago, a director of a mammogram project, realizing even back then that routine mammograms may not actually be saving women’s lives, asked as she lay on her death bed before succumbing to breast cancer herself, “Are we brainwashing ourselves into thinking that we are making a dramatic impact on a serious disease before we brainwash the public?”

KEY TAKEAWAYS

  • There appeared to be a drop in breast cancer mortality in the UK and Denmark when routine mammograms were introduced, but not in Switzerland. A closer look at the UK and Denmark data shows that there were mortality drops in age groups of women not getting mammograms, as only those in the 50 to 64 age group began getting screened.
  • Similarly, the United States experienced a drop in breast cancer mortality right when widespread mammograms were introduced, but a more dramatic drop was found in women getting less screening and an even larger drop was seen in breast cancer mortality among those not getting mammograms at all.
  • Breast cancer mortality began dropping around the world at the same time, regardless of when mammography screening began, thought likely due to the introduction of tamoxifen, an estrogen-blocking drug.
  • Randomized controlled trials have found that routine mammograms may reduce mortality from about five in a thousand dying from breast cancer without screening down to four in a thousand, so risk of death for women invited for routine screening is almost the same as for those not getting mammograms.
  • When cardiac and lung cancer deaths caused by radiation treatments given to women who had been overdiagnosed with pseudo-disease and unnecessarily treated for cancer, as a result of mammography, there appears to be no mortality benefit at all.
  • By the time breast cancer is caught by mammograms, they may have been growing for decades. Without mammograms, breast cancer may not be caught for 22.8 years. With mammograms, however, breast cancer may grow and spread for 21.4 years, nearly the same amount of time.
  • Nine out of ten women may still be unaware, overestimating the mortality reduction from mammograms by ten-fold or more, a percentage also seen in men who think similarly about prostate cancer screening.

Because “early” detection is actually really late, we can’t wait for a diagnosis to start eating more healthfully. Get going with these videos and tips: 

There is so much confusion when it comes to mammography, combined with the corrupting commercial interests of a billion-dollar industry. As with any important health decision, everyone should be fully informed of the risks and benefits, and make up their own mind about their own bodies. This is one installment in my 14-part series on mammograms, which includes: 

For more on breast cancer, see my videos Oxidized Cholesterol 27HC May Explain Three Breast Cancer Mysteries, Eggs and Breast Cancer and Flashback Friday: Can Flax Seeds Help Prevent Breast Cancer?

I was able to cover colon cancer screening in just one video. If you missed it, see Should We All Get Colonoscopies Starting at Age 50?.

Also on the topic of medical screenings, check out Flashback Friday: Worth Getting an Annual Health Check-Up and Physical Exam?, Is It Worth Getting Annual Health Check-Ups? and Is It Worth Getting an Annual Physical Exam?. 

In health,

Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live presentations:

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