Online

ESTRO 2020

Session Item

Physics track: Dose measurement and dose calculation
9319
Poster
Physics
00:00 - 00:00
Left breast radiotherapy: what is the dose received by the left ventricle ?
Dorra Aissaoui, Tunisia
PO-1418

Abstract

Left breast radiotherapy: what is the dose received by the left ventricle ?
Authors: Rim Abidi.(Faculty of Medecine Of Tunis - Salah Azaiz Institute, Radiation Oncology, Tunis, Tunisia), Dorra Aissaoui.(Faculty of Medecine Of Tunis -Salah Azaiz Institute, Radiation Oncology, Tunis, Tunisia), Khalil Mahjoubi.(Faculty of Medecine Of Tunis - Salah Azaiz Institute, Radiation Oncology, Tunis, Tunisia), Chiraz Nasr.(Faculty of Medecine Of Tunis - Salah Azaiz Institute, Radiation Oncology, Tunis, Tunisia)
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Purpose or Objective

Radiation therapy (RT) is one of the pillars of breast cancer treatment, it reduces the risks of recurrence and death. Nevertheless, the effects on the heart can be significant and caused serious clinical problem specially in radiation therapy on left breast. Cardiac damage is correlated to the heart-absorbed dose. The problems encountered can affect any subvolume of the heart, such as the left ventricle. Little is known about the long-term effects of irradiating specific segments of the left ventricle. Some previous studies have shown some detrimental effects of RT on the left ventricular diastolic functions. The aim of our study was to calculate the dose in the left ventricle and compare it with the dose of the whole heart.

Material and Methods

We performed a retrospective dosimetric study by contouring the left ventricular for 50 patients treated with radiotherapy for left breast carcinoma. Seven patients had a history of cardiac disease. Among the patients, 8 patients (16%) were classified luminal A, 22 were luminal B (44%), 17 were HER2-enriched (34%) and only 3 patients were tripe negative (6%). Radiotherapy was 3D conformational. The delivered dose was 50 Gy in 25 fractions for 43 women (86%) and 40 Gy in 15 fractions for 7 women (14%). Fourty six patients had locoregional radiotherapy and the remaining 4 patients had a whole breast or wall chest radiotherapy.

Results

The breast was irradiated by two tangential fields and the supraclavicular nodes by a direct field. Mean doses for the the whole heart were ranged from 1.3 Gy to 5.9 Gy with an average mean dose of 3.7 Gy. The doses of left ventricle were different. The average dose in the left ventricle was 4.9 Gy with extremes of 1.5 Gy and 9.4 Gy. A dose strictly inferior than 5 Gy was respected for 45 patients for the whole heart, and for 26 patients the left ventricular, respectively.  A dose strictly inferior than 3 Gy was respectect for 15 Patients for the whole heart, and for 7 patients the left ventricular, respectively.  

Conclusion

Doses in the heart and left ventricle can be high. Clinical and ultrasound cardiac examination may be necessary to detect radiation-induced cardiotoxicity, especially for patients with a history of heart disease or who have received Trastuzumab. In addition to mean heart dose, breast cancer RT treatment planning should also include constraints for cardiac subvolumes such as left ventricle to ensure adequate heart protection.