Late side effects in radio(chemo)therapy [R(CH)T] pose a critical limitation to patients' overall survival and quality of life. Even though toxicities of the heart are highly relevant for patients with cancer in the thoracic region, risk stratification models for these toxicities are lacking. In this study, liquid, functional and imaging biomarkers are being investigated for their use in prediction of cardiac toxicity following R(CH)T for patients with thoracic malignancies.

79 patients with non-small cell lung or esophageal cancer, and 246 patients with breast cancer to be treated with curative R(CH)T at the University Hospital Carl Gustav Carus Dresden, Germany will be included in this investigation. Dosimetric parameters from the applied radiation treatment plans, magnetic-resonance-imaging, electrocardiography, transthoracic echocardiography as well as blood-biomarkers will be collected to determine their predictive power against the primary endpoint of cumulative grade ≥ 2 cardio-toxicity (Common Terminology Criteria for Adverse Events [CTCAE] v 5.0) 3-5 years after R(CH)T.

Inclusion Criteria:

• Patients 18 years old or older
• Patient's consent and written consent is available
• Patients with the non-small cell lung cancer or esophageal cancer or breast cancer who have an indication for intended curative radio(chemo)therapy (in the case of breast cancer inclusion of female patients only)

Exclusion Criteria:

• Patients who are not capable of giving consent
• Pregnant women
• Patients with contraindications for MRI examinations (pacemakers, defibrillators, neurostimulators, aneurysm clips, cochlear implants, permanent make-up, metal splinters or osseosynthetic implants)
• Patients with insufficient kidney function (glomerular filtration rate (GFR) of less than 30 ml/min)
• Patients with the aforementioned tumour entities for whom a palliative indication exists

Only female patients with breast cancer (cohort 2)