Myth: “3D Mammograms are Lower Radiation”

Hello bOOb Blogettes:

Women are often told that 3D mammography will find more cancer and that it’s lower radiation than the “old” 2D mammogram. These are both over-statements. Let’s take a closer look..

First, it’s perplexing that medicine has decided to — instead of investigating a new non-invasive, non-radiative screening device — double-down and invest oodles of money into the new 3-dimensional (3D) “tomosynthesis” mammogram machines, touting them as the future for breast screening tests.

Finding research that justifies 3D mammogram’s use is difficult. The U.S. Preventative Services Task Force in 2016 concluded that “…the current evidence is insufficient to assess the benefits and harms of [3D mammography] as a primary screening method for breast cancer.”

Robert Smith, V.P. of cancer screening for the American Cancer Society, in 2019 merely contended, “We don’t have enough data to say [3D mammography is] definitely better…over [today’s] 2D.” Fast forward to today and the ACS website now touts loose support of 3D mammography by stating that it “…appears to lower the chance of being called back for follow-up testing,” and that 3D “…appears to find more breast cancers…”

One of the basic problems of 3D is that the mammography industry — with our government’s prior approval — pushed 3D out into the marketplace for use before it had substantial studies supporting it. Take this from a 2016 paper prepared for the U.S. Department of Health and Human Services: “In most cohort studies, cancer detection rates were somewhat higher with [3D] as compared to [2D]…”

“Somewhat higher”????

And “…the proportion of invasive cancers detected was similar to…”

“Similar to”????

And then it continues, “…or higher than the proportion detected with digital [2D] mammography alone.”

Not very impressive overall, is it, ladies?

What they don’t tell women before they go in for a 3D mammography exam (or afterwards, for that matter) is that the radiation a woman receives from a 3D machine can equate to twice the amount of the radiation level currently used during a 2D mammogram if the facility doesn’t have in place an FDA-approved software, a technology which allows both 2D and 3D X-ray pictures to be taken simultaneously. In other words, they are taking two different sets of X-rays — one in 2D and one in 3D — thus twice the radiation without the software.

The reason women should care about receiving twice the radiation amount is pointed out in a paper by Miglioretti, et al.: “Most U.S. practices offering screening [3D mammography] combine it with digital [2D] mammography, which at least doubles doses and the risk for radiation-induced breast cancer.”

And “they” have no idea when all mammography facilities will have that software. So currently, at the majority of facilities, women are subjected to at least twice the radiation if they undergo a 3D — and apparently inducing breast cancer at the same clip. And this from an industry that’s supposed to be watching out for women’s health.

Even the Radiological Society of North America admits this: “Digital breast [3D] and dedicated breast CT involve cancer risks that are one to two times those of digital [2D] or screen-film mammography.”

You would think that the radiological associations and mammography facilities would express concern over women’s being subjected to 3D’s higher radiation amount and that they would fix the software problem before rollout, wouldn’t you? But they did not.

La pièce de résistance regarding 3D’s premature roll-out for use comes from the governmental entity in charge of regulating breast cancer screening tools itself: “…Before granting approval, FDA determined there was a reasonable assurance that the new 3D devices were safe and effective for their intended use.”

“Reasonable assurance”? Okay, now this is getting comical…

The FDA website continues: “This determination was based on a review of clinical studies involving multiple radiologists and hundreds of cases.”

Forget the comedy, I’m back to being irritated.

Evidence-based medicine stands mightily on being — guess what? — evidence-based!  So where the heck is the so-called evidence? “Multiple radiologists” and “hundreds of cases” does not evidence make. Apparently, this bizarre “determination” made by the FDA was based on a small sample size of patient cases, while the phrase “multiple radiologists” is getting pretty darn close to the flat-out definition of “anecdotal evidence” — a phrase Medicine itself likes to throw around when something runs contrary to its liking.

But you can sleep well tonight, ladies, because our government is on top of things once again: The National Cancer Institute is conducting “the first randomized trial” comparing 2D against 3D mammography to be completed 2025 — at the earliest!  Until then, however, they will continue rolling out into mammogram facilities across the U.S. the new 3Ds without telling women about the little software problem — the one that may well be inducing breast cancer in a number of unsuspecting patients.

BOTTOM LINE: If you want to avoid mammogram’s radiation, consider a thermogram coupled with an ultrasound instead (see my previous post). If you do elect to get a 3D mammogram, call the facility ahead of time and ask if they have “the software” that takes both the 3D and 2D X-rays at the same time — so you can avoid double the radiation.

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Stay healthy,

Megan

Megan Smith, M.S.
Director, bOObs: The War on Women’s Breasts

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