Cardiotoxicity from Cancer Treatment: Understanding Risks and Advancements in Prevention - Dr P R L N Prasad

Cancer treatments have revolutionized survival outcomes, yet they come with unintended consequences, particularly affecting the heart. Chemotherapy, radiation therapy, and targeted therapies can lead to cardiotoxicity, a condition that compromises cardiac function and increases the risk of heart failure, arrhythmias, and vascular disease.

With growing awareness of this issue, cardiologists and oncologists are working together to mitigate these risks through improved screening, early intervention, and novel cardioprotective drugs.

How Cancer Treatments Affect the Heart

1. Chemotherapy-Induced Cardiotoxicity:

Certain chemotherapy agents, particularly anthracyclines (like doxorubicin) and targeted therapies (such as trastuzumab), are known to cause direct damage to cardiac tissues.

- Anthracyclines: These drugs generate oxidative stress, leading to the destruction of cardiac muscle cells. The damage is often cumulative, meaning the risk increases with higher doses.

- Trastuzumab & HER2 Inhibitors: These targeted therapies can interfere with molecular pathways essential for heart cell survival, leading to reversible heart dysfunction.

- Tyrosine Kinase Inhibitors (TKIs): Used in various cancers, TKIs can contribute to hypertension and heart failure by disrupting vascular signaling.

2. Radiation-Induced Cardiotoxicity

Radiation therapy to the chest area (such as in breast cancer, lung cancer, or Hodgkin’s lymphoma) can affect the heart in multiple ways:

- Coronary artery disease (CAD): Radiation can cause inflammation and fibrosis in coronary arteries, accelerating atherosclerosis.

- Valvular heart disease: Fibrosis from radiation can lead to thickening and dysfunction of heart valves, often appearing years after treatment.

- Myocardial fibrosis & restrictive cardiomyopathy: Radiation can induce fibrosis in the heart muscle, leading to stiffness and diastolic dysfunction.

3. Immunotherapy and Cardiovascular Risks

Newer immunotherapy agents, including immune checkpoint inhibitors, have been linked to myocarditis (inflammation of the heart) and vascular complications. While these drugs have improved cancer survival, their potential cardiovascular risks require careful monitoring.

Identifying High-Risk Patients

Not all cancer patients face the same level of risk for cardiotoxicity. Some factors that increase vulnerability include:

- Pre-existing cardiovascular disease

- Older age

- High cumulative chemotherapy doses

- Use of multiple cardiotoxic agents

- Concurrent radiation therapy to the chest

Onco-cardiology, a growing subspecialty, focuses on identifying these high-risk patients and implementing preventative strategies.

Preventing and Managing Cardiotoxicity

1. Early Detection Through Advanced Screening

Advancements in imaging and biomarkers have improved the ability to detect cardiac damage early.

- Echocardiography with strain imaging: Helps detect subclinical heart dysfunction before overt symptoms appear.

- Cardiac MRI: Provides detailed imaging of myocardial fibrosis and function.

- Biomarkers (Troponins, BNP, NT-proBNP): Elevated levels can indicate early cardiac injury.

Regular screening, particularly for patients receiving high-risk treatments, allows for timely interventions.

2. Development of Cardioprotective Medications

Several drugs are now being used to protect the heart during cancer treatment:

- Dexrazoxane: Approved for reducing anthracycline-induced cardiotoxicity, this drug acts as an iron chelator to minimize oxidative stress.

- Beta-blockers & ACE inhibitors: Drugs like carvedilol and enalapril have shown promise in reducing chemotherapy-induced cardiac dysfunction by improving myocardial perfusion and reducing oxidative stress.

- Statins: These cholesterol-lowering drugs have anti-inflammatory properties that may help prevent radiation-induced coronary artery disease.

3. Lifestyle Modifications and Supportive Therapies

- Regular exercise: Supervised cardiac rehabilitation programs have been shown to improve heart function in cancer survivors.

- Dietary interventions: A heart-healthy diet rich in antioxidants, lean proteins, and healthy fats can support cardiovascular resilience.

- Blood pressure and diabetes management: Strict control of risk factors reduces the likelihood of developing cardiac complications.

4. Personalized Cancer Treatment Strategies

Emerging research is focused on reducing toxicity while maintaining treatment efficacy.

- Liposomal formulations of anthracyclines: Deliver chemotherapy in a way that minimizes direct cardiac exposure.

- Reduced radiation dose strategies: Techniques like proton beam therapy focus radiation on tumours while sparing the heart.

- Targeted therapies with improved safety profiles: Newer generations of drugs aim to provide cancer control with minimal cardiovascular side effects.

Future of Cardio-Oncology

The intersection of oncology and cardiology has led to new multidisciplinary care models. Onco-cardiology programs are now being integrated into major cancer centres, allowing for real-time monitoring and proactive intervention.

- Artificial Intelligence (AI) in risk prediction: AI-driven models are being developed to identify patients at the highest risk of cardiotoxicity.

- Next-generation cardioprotective drugs: Research is underway to develop therapies that prevent heart damage without compromising cancer treatment efficacy.

As cancer survival rates continue to improve, protecting heart health must be a priority. By identifying high-risk patients early, integrating cardioprotective strategies, and advancing drug development, the medical community is taking significant strides in reducing the burden of cardiotoxicity.

A collaborative approach between oncologists and cardiologists will be the key to ensuring that cancer survivors not only beat cancer but also maintain long-term heart health.

For patients undergoing cancer treatment, regular cardiac screening, lifestyle modifications, and discussions with both their oncologist and cardiologist can help mitigate risks and improve quality of life.