MRI and needless mastectomies: Perfect Together!

MRI Scans as Overtreatment for Breast Cancer

Yesterday, while scouring KevinMD, I stumbled across a post from “Respectful Insolence,” a blog authored by an academic surgeon/scientist who dubs himself “Orac.” In the post, Orac reports that this Wednesday at the American Society of Clinical Oncology (ASCO) 2008 Annual Meeting,researchers from the Mayo Clinic will be reporting on a disturbing correlation between the use of breast magnetic resonance imaging (MRI) and a rise in the number of women having mastectomies.

In this context, Orac offers a cogent, compelling perspective on why too much cancer screening can harm patients. Orac’s worries specifically relate to using MRI scans to detect breast cancer. Advocates of the procedure rightly claim that MRI scans can detect more growths than other techniques, including mammography [i.e. an x-ray] and a clinical examination.

The MRI technology detects so much that, as the New York Times put it last year, the scans reveal “all sorts of suspicious growths in the breast, leading to many repeat scans and biopsies for things that turn out to be benign.”

In other words, breast MRI scans are so sensitive that if you have breast cancer, there’s an almost 100 percent chance that they’ll detect it; but the technology produces many false positives because it’s not as good at distinguishing between malignant and benign growths. As Orac puts it: “…MRI [scans] now routinely "section" people into "slices" much thinner than 1 cm, making our imaging sensitivity considerably higher than it was 14 years ago.

The problem is that while many people undergo malignant changes in various organs as they grow older than most will never actually develop “clinically apparent cancer.” In fact, some studies have shown that MRI scans accurately detect breast cancer just 30 percent of the time. Though most studies place this rate at a higher level, they also show that mammographies (using x-rays to examine the breast) lead to fewer false positives than MRI scans.