More false positives with breast exam than mammogram

Source:  Journal of the National Cancer Institute, Chiarelli, A., 2009; 101: 1236-43; Barton M., 2009; 101: 1223-25; www.breastcancer.org

Okay, some advice and some terms.  First, women should be performing self breast exams (minds out of the gutter, or enlist a friend, whichever).  The studies referenced compare physical exams by a doctor with current mammography.  So what are “false positives?” Apart from a really poor usage of language, “false positives” in the medical world occur when a benign (non-cancerous) abnormality is felt to look like a malignant (cancerous) one. Like what you ask?  Suspicious calcifications; architectural distortion, a cyst or a lump, to name a few.

Why is this important? I will slow down for those of you in the back rows.  If  an otherwise healthy patient has a “false positive” on a breast exam by a physician, certain protocols, which may include a needle biopsy or other invasive study are performed. Okay, so you require additional testing and a small incision in your breast, big deal, right?  Right.  Because “subtle findings” are not always detected on diagnostic studies, the breast self examination (BSE) and office physical exam remain useful tools in the diagnosis of breast cancer.  Too many “false positives” and expensive insurance dollars used on follow up testing for “false positives” and protocols have a way of changing.  Funny how that works.

So what are the numbers?  The study of some 290,000 Canadian women (No their breasts aren’t colder children), found that physical breast exam and mammogram combined were 95% accurate in detecting breast cancers. Mammography alone was 89% accurate. Combined there was a 12% rate of “false positives” while Mammograms alone only had a 7.4% rate of “false positives.“  In other words, for every cancer detected by a doctor breast exam, there were 55 “false positives.”  Mammography Centers appear to be in the forefront of pushing for the primary reliance on mammograms.  Again, funny how that works.  It’s an apportionment thing.

So there appears to be some statistical support for the false positives.  However even a math idiot like me will note that that the difference in accuracy are also better with both clinical breast exam and mammography combined.  And since it’s better to be accurate than good, or something like that, I think we should take this into consideration, but not invest too much consideration.

Posted by David Marc Schwadron, Esq.