Dados do Trabalho

Título

The use of Continuous Positive Airway Pressure (CPAP) significantly reduces the dose to the heart and cardiac substructures: a comparative study.

Introdução

Radiotherapy (RT) is a key component in the treatment of women with early breast cancer. In recent years, the dose received by cardiac structures has been gaining attention, mainly due to the risks of severe cardiac complications and potential for long-term cardiac mortality. Thus, efforts have been made to develop techniques that reduce the dose received in cardiac structures in order to mitigate these risks.

Objetivo

To evaluate the dose reduction in cardiac structures in patients with left-sided breast cancer undergoing hypofractionated radiotherapy using Continuous Positive Air Pressure (CPAP).

Método

Eleven women diagnosed with initial left-sided breast cancer undergoing hypofractionated radiotherapy were simulated and planned with phantom tomography and breast ramp with (C-CPAP) and without the use of CPAP (S-CPAP) in the same procedure. A CPAP pressure of 18mmHg was used and adapted according to patient acceptance. The simulation was performed to deliver a dose of 40 Gy/15 fractions, with the goal of 95% of the PTV receiving 95% dose. The heart was contoured into substructures (D and E atrium, D ventricle, E ventricle, whole heart), the E ventricle was divided into: Septal wall (PS), posterior (PP), lateral (PL) and anterior (PA). Left, circumflex, and right anterior descending coronary arteries were bypassed. Mean (Dmed), maximum (Dmax), V5Gy and D2% doses were collected in all cardiac substructures. The heart was further evaluated by V8Gy, V16Gy, V20Gy and V25Gy. The mean dose in the groups was compared with the two-tailed Student t Test with p < 0.05 considered significant.

Resultados

The C-CPAP had a significant increase in lung volume of 38% compared to the S-CPAP (p=0.0002). No significant difference was observed in 95% PTV and plane homogeneity between C-CPAP vs S-CPAP. Considering the heart a significant difference between C-CPAP and S-CPAP for V5Gy (p=0.005), V8Gy(p=0.006), V16Gy (p=0.003), V20Gy (p=0.02), V25Gy (p=0.003) . Analyzing the cardiac substructures a significant reduction (p<0.05) in Dmed, Dmax, V5Gy and D2% for the E ventricle, D,PA and PL of the left ventricle comparing the C-CPAP vs S-CPAP group was observed. A significant 28% (p=0.008) reduction in Dmax in the left anterior descending coronary artery was observed in the C-CPAP.

Conclusão

The use of C-CPAP significantly reduced the dose across the heart, cardiac substructures and coronary artery. CPAP could be an alternative for services that do not have respiratory control systems for the treatment of breast cancer.

Palavras-chave

Breast Cancer, CPAP, Radiotherapy