Chemo and Radiotherapy-induced Cardiomyopathy
Chemotherapy toxicity is continuously increasing due to the constantly growing number of patients treated with chemotherapy, biological drugs and / or radiotherapy, often combined and in cumulative doses, and of cancer survivors. The predisposition to cardiotoxicity depends on genetic factors as well as on individual and
environmental factors (e.g. age and presence of other pathologies, such as ischemic heart disease, hypertension, diabetes, alcohol abuse, smoking).
Cardiotoxicity can occur during therapy or months or even many years later. Most patients are asymptomatic, and only instrumental tests can demonstrate the damage caused by chemotherapy and/or radiotherapy: arrhythmias, pericardial effusion, reduced left ventricular contractility, and even clear signs of dilated cardiomyopathy. More rarely, it presents with congestive heart failure and even myocardial infarction. Pericarditis is common after radiotherapy to the mediastinum or left breast area.
The effects of different types of chemotherapy drugs are relatively well understood. Conventional drugs, such as anthracyclines, cause irreversible myocardial damage because they directly damage heart cells (cardiomyocytes). Newer anticancer drugs can cause high blood pressure, arrhythmias, left ventricular dysfunction, and heart failure, but their effect appears to be reversible and less potent. The effect also depends on the total dose of the drug per body surface area and the combination of different drugs, such as cyclophosphamide, trastuzumab, and taxanes, female gender, previous heart disease and high blood pressure, and/or radiation therapy cycles that include portions of the heart.
For example, for the anthracycline class of drugs (e.g. Doxorubicin and Epirubicin), the maximum cumulative toxic dose of doxorubicin is between 400-550 mg / m2. In some patients, ventricular dysfunction, which is usually asymptomatic, may however, even begin at lower doses, about 200 mg / m2.
However, approximately one-third of treated patients with trastuzumab may develop dilated cardiomyopathy (DCM). However, its cardiotoxicity is not dose-dependent and is often reversible with discontinuation of therapy. Approximately 1% of patients develop DCM when trastuzumab is administered alone, but this percentage rises to 3% when it is combined with an anthracycline and cyclophosphamide.
Prevention of damage seems possible with the administration of some drugs.
Cardiotoxicity after radiotherapy
Treatment of breast cancer and Hodgkin's lymphoma with radiotherapy involves irradiation of portions of the heart and may cause short-term reactions (usually pericarditis even with abundant pericardial effusion), but especially after many years.
The long-term consequences, usually between 10 and 20 years, sometimes even after 30 years, involve the coronary arteries, with manifestations of angina and myocardial infarction, the left ventricle with thinner walls and left ventricular dysfunction, valvular damage, atrioventricular blocks, fibrosis of the pericardium which becomes less elastic and/or chronic pericardial effusion.
Currently, radiotherapy techniques can reduce the doses of radiation delivered and appear to be safer and more effective but it is not proven whether they have reduced long-term complications.
