According to the AP, researchers at the Mayo Clinic have found that a new test caled Molecular Breast Imaging (MBI) may be a useful procedure for women who are at higher risk of breast cancer. In a study of 940 women with denser breast tissue (which makes it harder to detect cancers) and a higher risk of the disease, the study found 13 tumors in 12 patients, eight using MBI, one with only mammography, 2 by both methods and two by neither (detected later by other means). The MBI had a slightly lower rate of false positives than mammograms and also lower than MRI’s which have a much higher rate of false alarms. The MBI is also about half the cost of MRI’s.

Ok, so much for the good news. First, note above that the mammograms only detected 3 out of 13 of the cancers in dense tissue, not exactly an impressive record given that so many women have dense breast tissue. Also note that the total number of cancers was less than 2% of the women studied. Which means that exposing 98% of the participants to a high-dose radiation test (see below) was of no benefit.

But more importantly, we need to look at who funded the study. Yes it was done at the Mayo Clinic, but it was funded by Susan G. Komen For the Cure Foundation and Bristol-Myers Squibb who makes the imaging agent used in the study. Can anyone say vested interests? While we fully believe in the integrity of the work done by the Mayo Clinic, this hardly qualifies as an independent study and the results are, therefore unfortunately suspect.

One other big caution–the test uses 8 to 10 times more radiation than mammograms (MRI’s use none). And radiation is a known carcinogen. Recent studies have suggested that other high dose radiation tests such as CT scans need to be used with caution for that very reason. However the Mayo website tells us,

“CT scan risks are similar to those of conventional X-rays.”

Not so, according to U.S. News in their analysis of the safety of CT scans,

“(O)ne chest CT is around 10 millisieverts of radiation and a traditional chest X-ray only 0.02 millisieverts.”

Given that the Mayo Clinic conducted the tests on this new procedure, one has to be concerned at their apparent denial of the risks of higher doses of radiation. Before hailing this as a fabulous new tool, it would seem appropriate to question whether the diagnostic benefits are worth the risk of subjecting women who are already at risk of cancer to such high doses of a known carcinogen.