Transparent blue image of human heart with monitored beat, which can be abnormal in people with long QT syndrome
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Chemotherapeutic agents are widely known to carry an increased risk of heart failure and other forms of cardiovascular damage. A new study from the University of Toronto finds that Black patients or patients of African ancestry are at particular risk, with 71% higher odds of experiencing cardiotoxicity compared to White patients.

Researchers performed a systematic search of several databases—including Medline, Embase, Pubmed, and others—of all studies reporting on cardiovascular toxicity in cancer patients of different racial/ethnic backgrounds receiving chemotherapy. After screening 7,057 studies, 24 studies representing 683,749 participants were included in the final review. The analysis was presented at the American College of Cardiology’s Advancing the Cardiovascular Care of the Oncology Patient 2023 conference.

“Our study confirmed what we have seen in other medical studies, that Black patients tend to have worse outcomes,” says Wondewossen Gebeyehu, BSc, a medical student at the University of Toronto and lead author of the study. The study revealed that Black race or African ancestry was associated with an increased odds of chemotherapy-associated cardiotoxicity (unadjusted OR 1.71, 95% CI 1.40-2.10). In addition, Black race or African ancestry was also associated with 92% higher odds of congestive heart failure diagnosis.

The chemotherapies used in the included studies include anthracyclines like doxorubicin and daunorubicin, as well as trastuzumab and hormonal therapies.

Prior reports have commented that these disparities exist, but they have not systematically characterized what may be contributing to them. This study will continue to scour the results to see if the researchers can find differences depending on the cancer type, chemotherapy drug, and other influences.

“There are a number of potential factors that could be interacting to manifest these disparities,” says Gebeyehu. Some could be socioeconomic and related to access to quality care. “Can these patients get to appointments? Are they followed closely, including monitoring their cardiovascular health? Are the patients aware of the risks even prior to starting chemotherapy? These are questions we need to ask and answer.”

The team also highlights that Black patients are under-enrolled in clinical trials that develop new drugs. “We have to wonder whether chemotherapeutic agents are poorly optimized for different populations, such as different racial or ethnic groups,” adds Gebeyehu. “Do today’s trials capture adverse side effects in different groups? Is their performance equal between different racial groups?  We just don’t know how that under-representation affects how well the drugs work in different groups.”

Another influence may involve the history of science itself and the history of medical institutions and how they interact with different racial groups. “It is well-documented that most healthcare settings are not perceived as safe by Black patients,” says Gebeyehu. This lack of trust in healthcare providers may influence their willingness to participate in clinical trials or follow-up appointments for their own treatment and care.

The study highlights the need for further study to determine the underlying factors contributing to these disparities so they can be reduced.

“The most important message for patients is that they should not avoid chemotherapy, as the most important thing is making sure they get the best cancer treatment possible,” Gebeyehu said. “For clinicians, it is important to be aware of these higher odds of cardiotoxicity faced by Black patients. Understanding these disparities will hopefully lead to clinicians having more conversations around reducing the cardiovascular risk associated with chemotherapy and targeted efforts to cater to groups at higher risk.”

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