Cancer can significantly affect heart health. The impact on the heart can stem directly from the cancer itself, such as a tumor invading cardiac tissue, or more commonly, indirectly from the demanding treatments used to combat the disease. Understanding these connections is important for patients and healthcare providers to manage cancer care comprehensively.
Direct Effects of Cancer on the Heart
Cancer can directly involve the heart. Malignant cells may spread to the heart through the bloodstream, lymphatic system, or direct invasion from nearby tumors. This direct infiltration can impair the heart’s ability to pump blood, potentially leading to heart failure or irregular heart rhythms. Tumors can invade the pericardium, the sac surrounding the heart, causing fluid buildup that compresses the heart and impedes its function (cardiac tamponade).
Some cancers can also trigger paraneoplastic syndromes, where substances released by cancer cells affect distant organs, including the heart, even if the cancer has not spread there. These substances can lead to inflammation of the heart muscle (myocarditis) or the pericardium (pericarditis). Paraneoplastic syndromes can cause heart muscle damage, indicated by elevated cardiac troponin I, even without direct tumor invasion.
Cancer can also increase the risk of blood clot formation. Cancer cells can release chemicals that promote clot formation in veins or arteries. These clots can travel to the lungs, causing a pulmonary embolism, or to the heart, potentially leading to a heart attack or stroke. This elevated risk can persist for more than five years after a cancer diagnosis.
Treatment-Related Heart Complications
Cancer treatments are a common source of heart complications. Chemotherapy agents, particularly anthracyclines like doxorubicin, can damage heart muscle cells, weakening the heart’s pumping ability, leading to cardiomyopathy and heart failure. This damage can manifest months or even years after treatment, with risk increasing with higher doses. Other chemotherapy drugs may contribute to high blood pressure or irregular heartbeats.
Radiation therapy directed at the chest, often for lung or breast cancers, can harm the heart. Radiation exposure can cause inflammation and scarring of the heart’s lining (pericarditis), damage to heart valves, or hardening of coronary arteries, potentially leading to coronary artery disease. Risk depends on radiation dose, area treated, and existing heart health.
Newer targeted therapies, designed to attack cancer cells, can have cardiovascular side effects. HER2 inhibitors, such as trastuzumab (for certain breast cancers), may cause heart dysfunction and heart failure. VEGF inhibitors, which block blood vessel growth to tumors, can elevate blood pressure and sometimes lead to heart failure.
Immunotherapies, which harness the immune system to fight cancer, can trigger immune-related adverse events affecting the heart. Myocarditis, an inflammation of the heart muscle, is a rare but serious complication of immunotherapies. This condition can lead to rapid heart failure and is thought to involve the immune system mistakenly attacking heart cells.
Monitoring and Protecting Heart Health
Given the potential for cardiac complications, monitoring heart health during cancer treatment has become important, leading to the emergence of cardio-oncology. This discipline focuses on preventing, monitoring, and treating cardiovascular issues in cancer patients and survivors. Cardio-oncologists work alongside oncology teams to optimize patient outcomes by balancing treatment needs with heart protection.
Regular screening and monitoring are integral to safeguarding heart health. Common tests include echocardiograms, which provide images of the heart’s structure and function, and electrocardiograms (EKGs), which record the heart’s electrical activity. Cardiac biomarkers, such as troponin and natriuretic peptides, may be measured to detect early signs of heart muscle damage or stress.
Managing pre-existing cardiovascular risk factors is a significant protective measure. Controlling conditions like high blood pressure, diabetes, and high cholesterol before and during cancer treatment can reduce the likelihood of developing heart complications. Lifestyle recommendations, such as maintaining a balanced diet, engaging in regular physical activity, and avoiding smoking, contribute to overall heart health and can mitigate risks associated with cancer therapies. Patients should be vigilant for symptoms like shortness of breath, swelling in the legs, chest pain, or unusual fatigue, and report them to their care team immediately.