Radiotherapy planning scans may be a rich untapped source of information for estimating the risk of cardiovascular disease (CVD) in breast cancer patients, a large study suggests.
Researchers found that breast cancer patients with a coronary artery calcifications (CAC) score exceeding 400 had nearly four times the adjusted risk of fatal and nonfatal CVD events when compared with patients who had a CAC score of 0.
Patients with scores exceeding 400 also had more than eight times the risk of coronary heart disease events. The associations were especially strong in the subset of patients who received anthracycline-containing chemotherapy.
, of University Medical Center Utrecht (the Netherlands) at the 12th European Breast Cancer Conference.
Dr. Verkooijen noted that, over the past 50 years, breast cancer has dramatically declined as a cause of death among breast cancer survivors, while CVD has continued to account for about 20% of the total deaths in this population.
CACs are sometimes incidentally seen in radiotherapy planning CT scans. “Right now, this information is not often used for patient stratification or informing patients about their cardiovascular risk, and this is a pity, because we know that it is an independent risk factor, and, often, the presence of calcifications can occur in the absence of other cardiovascular risk factors,” Dr. Verkooijen said.
Dr. Verkooijen and and colleagues from the Bragataston Study Group retrospectively studied 15,919 breast cancer patients who had radiotherapy planning CT scans during 2004-2016 at three Dutch institutions.
The researchers used an automated deep-learning algorithm (described in) to detect and quantify coronary calcium in planning CT scans and calculate CAC scores, classifying them into five categories.
The median follow-up was 51.6 months. Most women (70%) did not have any calcium detected in their coronary arteries (CAC score of 0), while 3% fell into the highest category (CAC score of >400).
The incidence of nonfatal and fatal CVD events increased with CAC score:
- 5.1% with a score of 0.
- 8.5% with a score of 1-10.
- 13.5% with a score of 11-100.
- 17.6% with a score of 101-400.
- 28.0% with a score greater than 400.
In analyses adjusted for age, laterality of radiation, and receipt of cardiotoxic agents – anthracyclines and trastuzumab – women with a score exceeding 400 had sharply elevated adjusted risks of CVD events (hazard ratio, 3.7), of coronary heart disease events specifically (HR, 8.2), and of death from any cause (HR, 2.8), when compared with peers who had a CAC score of 0.
On further scrutiny of CVD events, the pattern was similar regardless of whether radiation was left- or right-sided. However, the association was stronger among women who received anthracyclines as compared with counterparts who did not, with a nearly six-fold higher risk for those with highest versus lowest CAC scores.
When the women were surveyed, nearly 90% said they wanted to be informed about their CAC score and associated CVD risk, even in the absence of evidence-based risk reduction strategies.