Dosimetry of the left anterior descending coronary artery in left breast cancer patients treated with postoperative external radiotherapy

Publication date: March–April 2018
Source:Reports of Practical Oncology & Radiotherapy, Volume 23, Issue 2
Author(s): Adela Poitevin-Chacón, Jessica Chávez-Nogueda, Rubí Ramos Prudencio, Alejandro Calvo Fernández, Alejandro Rodríguez Laguna, Jesús Linares, Julio César Martínez
AimTo evaluate the dose distribution to the left anterior descending (LAD) coronary artery in patients treated with postoperative three-dimensional conformal radiotherapy (3DCRT).BackgroundPostoperative radiotherapy may increase the risk of heart disease, particularly in patients with left-sided breast cancer. Clinical data on doses to the LAD are limited.Materials and methodsRetrospective study of 14 patients who underwent postoperative 3DCRT for left breast cancer in 2014. All data were retrieved from medical records. Means, medians, ranges, and percentages were calculated.ResultsThe mean dose to the LAD in patients with V25<1% was 0.12cGy. Dmean, Dmax and V25 to the heart were, respectively, 3.7Gy (range, 0.9–4.18), 40.3Gy (9.28–62.9), and 1.59cGy. The mean Dmean and Dmax values in the sample were 9.71Gy and 33.2Gy, respectively. The maximum dose to the LAD (D2%) ranged from 3.66 to 53.01Gy. Due to the spacing of the CT slices (5mm), it was not possible to completely contour the entire artery. The mean dose to the heart (3.3Gy) was considered acceptable.ConclusionsThe maximum dose to the LAD was as high as 53Gy, suggesting an increased risk of cardiac morbidity. This study underscores the value of contouring the LAD and the value of the breath hold technique to reduce maximum cardiac doses. Smaller CT cuts (2.5mm) can improve contouring. Larger studies with long-term follow up are needed to determine the radiation tolerance dose for the LAD.



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