Not enough cancer patients are aware of the potential adverse effects of cancer treatment on their heart.
At the same time, the new research shows that most of these people have limited or no knowledge about the cardiovascular risks because their doctors never tell them.
The authors recently presented their findings at EuroHeartCare 2019, a congress of the European Society of Cardiology, which took place at the start of May in Milan, Italy.
"Depending on the type of chemotherapy and radiotherapy, between 1% and 25% [of] cancer patients may develop heart failure due to cancer treatment," warns study author Prof. Robyn Clark.
"Risk," she adds, "also depends on cardiovascular risk factors, such as smoking and obesity. Better monitoring of the heart and intervention before, during, and after treatment can prevent or lessen the impact of this cardiotoxicity."
Cancer patients unaware of risks
The study authors explain that people who experience heart problems following cancer treatment may not do so immediately.
In fact, according to research investigating heart failure risk in people who have undergone cancer treatment, therapy-related heart failure can develop up to 20 years after the treatment has concluded.
In the current study, the researchers looked at the medical records of 46 people who had received cancer treatment at one of three hospitals between 1979 and 2015. All of these people had cardiotoxicity (damage to the heart muscle), and the research team selected them at random.
The investigators found that of these 46 patients, only 11% had received a referral to a specialized cardiologist before beginning chemotherapy, and medical professionals had only referred 48% of them to a heart failure clinic following their treatment.
Prof. Clark and colleagues also note that among the individuals whose records they studied, about 40% were overweight or had obesity, 41% had smoked or were still smoking, 24% used alcohol regularly, 48% had high blood pressure, and 26% lived with diabetes.
Patients miss crucial self-care information
The researchers then looked at the provision of care received by subsets of cancer patients during two different periods: 1994–2011 and 2012–2015. They selected these dates so that they could look at the effect of the publication of the European Society for Medical Oncology's Clinical Practice Guidelines, which appeared for the first time in 2012.
When they compared the provision of care in the two periods, the investigators found that the rate of appropriate heart care did actually increase.
The percentage of people who received a referral to a cardiologist before starting chemotherapy went from 0% to 23%, while the percentage of patients receiving a baseline echocardiogram — a scan that allows doctors to assess heart function — rose from 57% to 77%.
Moreover, the researchers went on to interview 11 cancer patients, of whom seven also belonged to the randomly selected group of 46 people whose medical records the investigators initially analyzed.
None of these individuals were aware of their heart health needs, and while more than half of the interviewees reported developing more healthful eating habits following their diagnosis, none of them had a solid understanding of what a balanced diet should entail.
Doctors should issue more referrals
Based on all of these findings, the study authors stress the importance of monitoring heart health in people about to undergo cancer treatment and adjusting care to meet each person's needs.
"Monitoring the heart throughout the cancer journey can ensure it is protected. Cardiotoxicity can occur even in people without cardiovascular risk factors since drugs like anthracyclines and trastuzumab are toxic to the heart, so it is an innocent bystander."
Prof. Robyn Clark
Prof. Clark and team also note that doctors should explicitly tell cancer patients about the risks that their recommended cancer treatments carry and advise them on the best ways to minimize heart risks — for instance, by working to improve relevant lifestyle factors, such as physical activity and diet.
However, if a cancer patient does develop heart failure, they can still access helpful therapies as long as doctors keep a close eye on the condition, says Prof. Clark.
The researchers explain that healthcare professionals can identify cardiotoxicity either by using echocardiograms or cardiac imaging or by looking for specific biomarkers. People who may develop or already have heart failure could receive angiotensin converting enzyme inhibitors or beta-blockers as a treatment.
At the same time, people whose cancer treatments are damaging their heart health could benefit from modified cancer therapies that minimize this harm, if their doctors closely monitor any cardiovascular developments.
"For cancer patients who do develop heart failure, there are clinics that will improve their quality of life, but our study shows many are not referred," Prof. Clark points out.
"Telephone calls to support and monitor those with cancer and heart failure would reduce the burden of hospital appointments, which patients said was a priority," she emphasizes.