ESTRO 2024 - Abstract Book

S697

Clinical - Breast

ESTRO 2024

1 Centre Hospitalier Victor Dupouy, Radiation therapy, Paris, France. 2 INSERM, Radiation Epidemiology Team, CESP U1018, Villejuif, France. 3 Gustave Roussy, Radiation therapy, Villejuif, France. 4 INSERM, U1030, Villejuif, France. 5 Gustave Roussy, Medical Physics, Villejuif, France. 6 Hôpitaux Universitaires Paris-Est, Assistance Publique-Hôpitaux de Paris, Hôpital Saint Antoine, Cardiology, Paris, France. 7 INSERM, U856 Thrombose, Athérothrombose et Pharmacologie Appliquée, Paris, France. 8 Unicancer, Data & Partenariats, Le Kremlin-Bicêtre, France. 9 Unicancer, Strategy, Le Kremlin-Bicêtre, France. 10 Gustave Roussy, Medical Oncology, Villejuif, France. 11 Centre Georges François Leclerc, Surgery, Dijon, France. 12 Centre Léon Bérard, Medical Oncology, Lyon, France. 13 Institut Curie, Medical Oncology, Paris, France

Purpose/Objective:

Non-metastatic breast cancer is a highly curable disease. Improvement in non- metastatic breast cancer patient’s survival brings major challenges including the management of treatment side effects that can be disabling and/or life threatening for millions of survivors. In recent years, cardiac toxicity has gain interest as one of the frequent late adverse events of cancer treatment. This is a real concern, especially since cardiovascular diseases constitute a leading cause of death. This study was carried out to assess risk factors according to tumor characteristics, patient comorbidities and treatment characteristics.

Material/Methods:

Data from the prospective, multicenter CANcer TOxicity cohort (CANTO, NCT01993498)[1], enrolling patients aged 18 and over at diagnosis of stage I-III breast cancer (BC) treated according to institutional guidelines were analyzed. Patient, tumor and treatment characteristics were collected at diagnosis (baseline) and three to six months after primary treatment completion (M0) defined as surgery, chemotherapy or radiotherapy, whichever comes last. Trastuzumab and endocrine therapy could be ongoing as well as reconstructive or prophylactic surgery. Outcomes of interest collected at baseline, M0, M12, M36 and M60 included cardiac events defined as any of myocardial infarction, rhythm and conduction disorder, myocarditis, pericarditis, valvular disease and ventricular dysfunction. We performed a multivariable analysis by logistic regression with SAS v. 9.4 using cardiac events (defined as any of: myocardial infarctions, ventricular dysfonctions, rhythm disorders, conduction disorders, pericarditis, myocarditis and valvular diseases) at any visit as the variable of interest for patients with at least one visit with collected data.

Results:

Between 2011 and 2019, 11 342 patients were included in CANTO with 10 596 patients having at least one visit with collected data. Of those, 47.4% had right-sided BC, 50.4% left-sided BC and 2.2% bilateral BC. Median age was 57 (IQR: 25-88), 60% of patients were post-menopausal. Most patients presented with T1 tumors at diagnosis (55.2%) and no histological nodal involvement (66.1%). Most tumors (75.7%) were invasive carcinoma of no special type. Elston-Ellis grade 1, 2, 3 amounted to 17.2%, 52.9% and 28.9% respectively (not known: 1%). Most tumors 86.5% expressed hormonal receptors (estrogen and/or progesterone) and 13.7% had Her2 overexpression. Over a third (37.4%) of the patients had one cardiovascular risk factor (defined as diabetes, hypertension, dyslipidemia, history of tobacco smoking or obesity), 15.0% had two, 3.9% had three, 0.5% had four and 0.01% had all five. History of cardiac events at baseline (defined as any of the previously cited events) was found in 9.2% of the patients.

Most patients (72.9%) had breast conserving surgery and 61.9% had a sentinel node biopsy. Radiation therapy was delivered in 91.8% of the patients mainly in 3D with normofractionated regimen (50 Gy in 25 fractions +/- boost),