How would you answer this: “What’s the best way to screen for breast cancer?” Nearly everyone, including breast cancer specialists and radiologists, will routinely answer this question with “Mammography.” But they’re wrong, at least by one definition of “best.” The question is not as simple as it seems. If one is using “best” to mean, “the most practical,” then YES, it’s screening mammography. Mammography has the infrastructure and expertise in place so that we can screen all women in the U.S. who are interested in doing so — and, mammography is the only imaging modality which has revealed in prospective, randomized trials that fewer women die of breast cancer when screened.
But what if “best” means “best?” That is, what if “best” means detecting cancers most reliably at the earliest stage? (I think this is what most women hear when the word “best” is used, but those clinicians who are answering the question with “mammography” as the answer are using “best” to mean something else entirely.) In fact, the best method for detecting breast cancer for the individual patient is MRI (magnetic resonance imaging). Very close at the heels of MRI is MBI, or molecular breast imaging, a nuclear medicine study. In fact, MBI can lay claim to having fewer false-positives and thus, preferred over MRI. Both MRI and MBI require the injection of a contrast agent — gadolinium for MRI and a radionuclide for MBI. Although MRI is widely accessible, with MBI playing “catch-up,” only time will tell about the safety of annual or biennial gadolinium vs. radionuclide, and this may be the deciding difference.
Then, for those women with dense breast tissue (another topic for later), ultrasound will actually find more cancers than mammography. For those with extreme density (over 75% “white” on X-ray), the fact is that mammography comes in dead last of all available options. For women with more modest levels of density, but still more than 50% of the area on mammography being “white,” it’s a toss-up as to whether mammography or ultrasound will find the most cancers. And when it comes to the new 3-D mammography (a definite improvement in cancer detection), ultrasound still identifies additional cancers missed by this new technology.
Mammography is far from “best” when one is talking about early detection capability. The bigger picture here is troubling — the so-called best recommendation for the general population is not always what is best for the individual. Currently, MRI screening is used only in high-risk individuals, where published detection levels (sensitivity) are 90% compared to only 40% using mammography alone. The same gap would be present in normal risk individuals as well, but screening the general population with MRI is so impractical that it has never seriously been considered…until now. A new “fast MRI” may make screening larger numbers of women with MRI more practical. Dr. Christiane Kuhl (Germany) has presented the first data on screening the general population with MRI, and it’s impressive — for women cleared by clinical exam and negative mammograms, and nearly all with screening ultrasound as well, Dr. Kuhl and her group identified 11 cancers per 1,000 patients at normal risk, roughly double the detection rate of mammography…after mammograms had already deemed these women as A-Okay.
The key is going to be identifying patients for ultrasound and MRI screening in a cost-effective manner. And it is for this reason that I am involved in two major research efforts to properly select patients for additional imaging, based not on future risk, but the current probability that a cancer has been missed by mammography. This blog will return to these research projects again and again. And for detailed information as to how and why breast cancer screening needs to be overhauled, check out my book: Mammography and Early Breast Cancer Detection: How Screening Saves Lives.