MBI: A Better Screening Tool for Younger Women?

PJ Hamel Health Guide
  • Despite last year’s US Preventive Services Task Force recommendations that women under age 50 don’t need regular screening mammograms, the vast majority of us continue to get a yearly mammogram beginning at age 40.

    But that yearly mammogram might not be offering women under 50 the protection against a serious breast cancer diagnosis they believe they’re getting. In fact, research shows that the majority of women under 50 have a less than 50% chance that their annual mammogram is spotting breast cancer in its earliest stages, when it’s most treatable.

    What’s the story?

    Dense breasts.

    In laymen’s terms, dense breasts are breasts that have more glandular and connective tissue than fat. This is a condition that’s clinically determined by the radiologist who reads your mammogram; you can’t simply look at yourself and say, “Yeah, I think I have dense breasts;” you have to ask for and read your complete mammogram report.

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    If the radiologist’s notes in your report read “heterogeneously dense” or “extremely dense,” you have dense breasts. 

    Why does it matter?

    It’s long been known that the denser a woman’s breast, the more difficult it is for a standard mammogram to pick up a tumor. On a mammogram, fat tissue appears dark/transparent; breast tissue is light/opaque, as is a tumor. The more connective/glandular tissue in a woman’s breast (the “denser” it is), the harder it is to see a tumor on a mammogram.

    Recent studies have also shown that women with extremely dense breasts are at four to six times the risk for breast cancer as women with non-dense (high-fat) breasts. So, dense breasts increase your risk of breast cancer; and they lower your chance of catching it early via mammography.

    That’s why you need to know whether you have dense breasts.

    If you do, what are your screening options?

    Currently, your best bet is still mammography; although it’s less than 50% effective for you, it’s still better than nothing.

    Many doctors are now recommending that women with dense breasts alternate their yearly mammogram with the more sensitive MRI. But MRIs have their downside, too. They’re expensive, invasive, and often inaccurate; while they do show more tumors than mammograms, they also have a high rate of false-positive results: up to 50%.

    So neither mammogram nor MRI is ideal. What else is there?

    Molecular breast imaging (MBI) is being touted as having “the potential to revolutionize breast imaging,” according to the Mayo Clinic’s online research magazine, Discovery’s Edge. The Clinic’s Dr. Deborah Rhodes and Dr Michael O’Connor have been working on this tool, an evolution of the technology used in PET scanning, for the past decade. The process uses gamma rays to spot cells that are reproducing quickly: cancer cells. Dense breasts can’t “hide” tumors, like they do with a mammogram. Even the tiniest, earliest tumors can be spotted via MBI.

    While recently approved by the FDA, Rhodes notes that it’s still probably 5 years away from being widely available. Further data needs to be collected over time; and it takes awhile for any new technology to make its way into the mainstream (and onto Main Street).

  • But preliminary, limited testing results look extremely positive. In a group of 1,000 women with dense breasts, a standard mammogram successfully spotted just 25% of the tumors eventually identified; while the MBI picked up 83%.

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    In practical terms, MBI screening is more invasive, and takes longer, than a mammogram. It involves an injection into your arm, and takes about 40 minutes.

    However, unlike the painful 40 pounds of pressure applied to your breasts during a mammogram, the pressure of an MBI is very light, and not painful. That alone will prove attractive to many women who struggle mightily with forcing themselves to endure the pain of an annual mammogram – and therefore end up skipping this important screening test altogether.

    MBI isn’t available yet; but keep it on your radar. If you have dense breasts – which applies to about 2/3 of us under age 50, and 1/3 of us 50 and over – it just might replace your yearly mammogram in the not-so-distant future.


Published On: April 21, 2011