This news release from the American College of Cardiology describes a study that suggests mammograms should be used to screen not only for breast cancer but also for calcium build-up in the breast arteries, which could be a sign of heart disease. The study looked at digital mammography and computerized tomography (CT) scans of 292 women who had been screened within the past year. A very high percentage of women (42.5 percent) were found to have calcium in their breast arteries. Among those women, 70 percent also had calcium deposits in their heart arteries. (The CT scans found calcium in breast arteries in 47.5 percent of the women.)
We observed a fair amount of fear mongering in the release (that sometimes carried over into news stories) and a lack of quantification of the benefits. We aren’t told how including this assessment from a mammogram improves lives.
Coronary heart disease (CHD), in which plaque builds up on the inner walls of coronary arteries, affects a wide number of both men and women. As the news release states, heart disease is the leading cause of death among women and that is confirmed by the National Institutes of Health. Intuitively, one expects new or improved screening tools would lead to earlier diagnosis and more effective efforts at prevention of heart disease. Physicians might recommend lifestyle changes, medication or surgery to help women lower their risk for CHD. However, more screening could also lead to more false positives and more stress, more invasive tests, perhaps more unnecessary aggressive treatments including long-term medications like statins and surgery. This news release matters because it encourages physicians to begin immediately to report on calcium build-up found during regular breast cancer screening mammograms because its “critical information that could be life-saving for some women.” This is very premature since the study was small and, as the release points out, there is no consensus among experts on using coronary arterial calcification as a predictor of heart disease.
The study is being presented at a large medical conference on April 3, and simultaneously published in a medical journal, Cardiovascular Imaging. But already the study has received significant media coverage with stories appearing in Reuters, the Wall Street Journal, Newsweek and dozens of other media outlets. Despite its small size and need for larger studies (as stated by the researchers in the release), a study author told Reuters that based on the research, “Women should ask their radiologists if there was any calcification in their breast arteries. This information can then be given to their primary care doctors to be used in conjunction with standard risk factors to determine if further evaluation (or treatment) would be of benefit.” That is a big leap from a news release that asks in its headline: “Mammograms: Another way to screen for heart disease?”
The news release discusses cost in terms of it being a no-cost screen, since the information would be gleaned from a woman’s mammogram for breast cancer. This is not the whole story. The study authors suggested that identification of calcification on breast screening would indicate the need for additional coronary artery screening. And if some 40 percent of women undergoing mammography have breast artery calcification, this will mean a lot of additional coronary imaging tests and possibly additional medications and surgery, all at unknown cost.
The release does attempt to quantify the accuracy of the test when it states that 70 percent of the women that were shown to have breast arterial calcification (BAC) were also found through CT scans to have coronary artery calcification (CAC). While that may sound impressive, the release doesn’t acknowledge that this equates to a 30 percent false-positive rate. So 30 percent of women may be unnecessarily worried or inconvenienced and sent for additional testing based on these results. Also, we’re not told what percentage of women who tested negative for breast calcification in fact would have have had CAC according to a CT scan of their chest. That’s an important piece of information that speaks to the test’s usefulness. And if it wasn’t addressed in the study, we think the release should have said so. We always encourage news release writers to address both the sensitivity and specificity of screening tests.
The release also suggests that measuring breast arterial calcification is a better, more accurate risk factor assessment tool than standard risk scores (Framingham Risk Score and the 2013 Cholesterol Guidelines Pooled Cohort Equations). But it doesn’t provide us with any quantification. Instead it says calcification is a “more powerful” measure for assessing risk than the standard risk assessment. What exactly does that mean?
The release didn’t acknowledge that false-positive scans can lead to additional expense, anxiety, further testing, and perhaps treatment with unnecessary medications that have unwanted side effects. Follow-up tests may also expose women to additional radiation.
A fairly good description of the study protocol is provided. The volunteer group included 292 women who had undergone digital mammography or CT scans within the past year. The group only included women with no previously known heart disease. The mammograms of the 124 women who were found to have BAC were sent to a second radiologist who was blinded to the BAC results. BAC was rated on a severity score of 0-12, with 12 being the most severe. The researchers found CAC present in 70 percent in the group of 124, while 63 percent of those with CAC also had BAC.
There is also reasonable attention to limitations. A quoted researcher says, for example, “Future prospective trials are needed to see what the prognostic significance of breast arterial calcification might be. Because the study involved women who received both mammography and CT scan for clinical indications, these women may have been more likely than the average woman to have coexisting conditions.”
The use of fear-mongering language was a weakness of this release. The release calls BAC a “red flag” and says, “Many women, especially young women, don’t know the health of their coronary arteries.”
That statement presumes that young women should know this information because it can lead to health benefits — something not established here. It’s not at all clear that BAC is a useful “red flag,” but it does seem pretty certain that this kind of language will cause women to worry about BAC, perhaps unnecessarily.
The release states that the Flight Attendants Medical Research Foundation was a partial funder. We aren’t told who else sponsored the research or if there were any potential conflicts of interest.
The release mentions alternatives, the standard risk assessment tools, as the Framingham Risk Score and the 2013 Cholesterol Guidelines Pooled Cohort Equations. Although it’s questionable, as noted above, if there is an accurate comparison.
The digital mammogram is widely used and available and neither the release or the study seem to be calling for additional testing beyond what is already taking place. So while availability is not specifically addressed, it’s pretty evident from the release that such testing is widely available.
The news release claims novelty through this statement: “Data from this study show for the first time a link between the amount of calcium in the arteries of the breast — readily visible on digital mammography — and the level of calcium buildup in the coronary arteries.”
It also notes, “Earlier research had shown a link between breast arterial calcification and atherosclerotic disease–even heart attack, stroke and other cardiovascular disease events, but researchers said these data provide a more direct relationship between the extent of calcified plaque in the mammary and coronary arteries, as well as a comparison to standard risk evaluation.”
The release does not cross our line on unjustifiable language. While some statements seem to imply that women will immediately benefit from the additional assessment of their mammograms, they are tempered with some cautionary language such as “these findings warrant further evaluation and validation in larger studies.”