Pre-radiotherapy CT scan may help identify CVD risk in women with breast cancer

The use of an algorithm to identify the presence of coronary artery calcifications (CAC) during radiotherapy-planning CT scans may help assess cardiovascular disease (CVD) risk in women with breast cancer, according to a study from the Netherlands.

“CAC on planning CT scans are very strongly associated with CVD, specifically coronary heart disease (CHD). This association is strongest in women treated with anthracyclines,” presented Professor Helena Verkooijen from University Medical Center Utrecht, the Netherlands, at EBCC 2020.

This multicentre, retrospective study included 15,519 patients with breast cancer who underwent radiotherapy between 2005 and 2016. Based on the radiotherapy-planning CT scans of the patients, the researchers used an automated deep-learning algorithm to identify the presence and extent of CAC and the scores were assigned into Agatston categories (0 [no CAC], 1–10, 11–100, 101–400, and >400 units).

Thirty percent of patients had CAC scores >0, with 5 and 3 percent having scores of 101–400 and >400, respectively (n=830 and 497). Patients with lower CAC scores tended to be younger than those with higher scores (eg, mean age 56 and 71 years for CAC scores 0 and >400, respectively). Individual linkage with various national databases helped identify CVD risk. Patients were followed up for a median 51.6 months. [EBCC 2020, abstract ORAL-008]

The number of CVD events (plus CVD-related death) increased with rising CAC scores (5.1, 8.5, 13.5, 17.6, and 28.0 percent in the 0, 1–10, 11–100, 101–400, and >400 unit groups, respectively).

A similar trend was noted for absolute risk of CHD and all-cause mortality.

After adjusting for factors such as age at time of CT scan and treatment (anthracycline or trastuzumab), increasing CAC scores were tied to increasing risk of CVD (adjusted hazard ratio [adjHR], 1.2 [CAC 1–10]; adjHR, 1.8 [CAC 11–100]; adjHR, 2.3 [CAC 101–400]; and adjHR, 3.7 [CAC >400]) compared with patients with no CAC.

The association between CAC score and risk of CVD appeared strongest among patients with CAC score >400 who were also treated with anthracyclines (HR, 5.4).

Risk of CHD was also raised with increasing CAC score (adjHR, 1.7, 2.8, 4.3, and 8.2 for 1–10, 11–100, 101–400, and >400, respectively) compared with patients with no CAC.

“We’ve seen great improvement in breast cancer survival, thanks in part to better treatment. However, treatments have side effects and some treatments – such as radiotherapy and certain types of cancer drugs – can increase the risk of CVD,” highlighted Verkooijen.

CACs are a strong, independent risk factor for CVD. While they are sometimes visible on radiotherapy-planning CT scans, this information is not often utilized, she said.

“This is a clever study because it shows us how the CT scans we are already taking can also be used to discover which women have the highest risk of CVD,” said EBCC 2020 chair Professor Nadia Harbeck from the University of Munich, Germany, who was not affiliated with the study.

“Now we need to do more research to find out what can be done to help minimize this risk, for instance whether patients’ cardiovascular health should be monitored or treated,” said Verkooijen.

“In my opinion, treating breast cancer means finding the right balance between maximizing chances of tackling the tumour, while minimizing the risks of side effects, including the risk of CVD,” she concluded.