The hidden cardiovascular risk emerging in cancer survivors

Cancer survivors face a substantially higher long-term risk of atherosclerotic cardiovascular disease (ASCVD) than the general population. Now, researchers at the Baker Heart and Diabetes Institute have identified another piece of the puzzle: cancer survivors carry significantly more high-risk plaque in their coronary arteries, the type of plaque most likely to rupture and trigger a heart attack.

The findings add to growing evidence of an important convergence between cancer and cardiovascular disease. In several common malignancies, including breast, prostate and colorectal cancer, cardiovascular disease has overtaken cancer recurrence as the leading cause of death in the years following diagnosis.

Coronary artery disease (CAD) is a major contributor to this excess cardiovascular risk, yet the underlying burden and characteristics of coronary plaque in cancer survivors have remained incompletely understood.

The new study compared cardiac CT scans from long-term cancer survivors, largely people with a history of breast and blood cancers, with scans from people without cancer who had a similar cardiovascular risk profile. All participants had early-stage coronary plaque and were not taking statins, allowing researchers to isolate differences in plaque burden and characteristics.

Using specialised software to measure both plaque volume and composition, the researchers found that cancer survivors had 10% more total plaque in their coronary arteries than people without cancer. More strikingly, they had 45% more high-risk plaque, the form associated with an increased risk of future heart attacks.

First author Dr Cheng Soh said the findings strengthen the case for moving beyond awareness of cardiovascular risk in cancer survivors towards more proactive assessment and management.

“Our previous studies have shown cancer survivors face nearly double the risk of cardiovascular disease,” Dr Soh stated. “This study adds to that picture by showing survivors also carry a greater volume of high-risk plaque. It tells us we need to be more proactive with heart risk assessment and management in this group.

The emerging convergence between cancer and ASCVD is driven by shared risk factors, overlapping pathophysiological mechanisms and the vascular effects of cancer treatment. Therapies including anthracyclines, radiotherapy, hormone therapies and immune checkpoint inhibitors further accelerate vascular injury and atherogenesis through endothelial injury, oxidative stress and lipid dysregulation.

The implications are already being reflected in clinical practice. Dr Joshua Wong, cardiologist and PhD research fellow at the Baker Heart and Diabetes Institute, is building integrated cardio-oncology programs at centres including Melbourne’s Peter MacCallum Cancer Centre. The aim is to ensure that improvements in cancer survival are not followed years later by preventable cardiovascular complications.

The next challenge is determining which cancer survivors require closer cardiovascular monitoring. Screening every survivor with a CT coronary angiogram would not be realistic from a cost perspective, making risk stratification a critical priority. The research team’s focus is now turning to identifying the survivors most likely to carry this high-risk plaque. Detecting those patients early could create an opportunity to intervene before a heart attack occurs.

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