Whole breast external beam radiotherapy in elderly patients affected by left-sided early breast cancer: a dosimetric comparison between two simple free-breathing techniques.

Elderly breast cancer patients are frequently affected by significant comorbidities that make sophisticated radiotherapy treatments particularly challenging. We dosimetrically analyzed two different simple free-breathing external beam radiotherapy (EBRT) techniques for the hypofractionated treatment of the left breast in elderly patients with a low compliance, to compare target coverage, and heart and left anterior descending coronary artery (LADCA) sparing. We developed radiation plans for 24 elderly patients using 3D conformal (3DCRT) field-in-field tangential technique and intensity-modulated (IMRT) tangential beam technique. Dose-Volume-Histograms (DVHs) were used to provide a quantitative comparison between plans. The median breast volume was 645 cm3. IMRT and 3DCRT plans comparison demonstrated no significant differences in terms of organ sparing for the heart. Regarding LADCA, mean dose (10.3 ± 9.5 Gy vs 11.9 ± 9.6 Gy, p = 0.0003), maximum dose (26.1 ± 16.1 Gy vs 29.1 ± 16.1 Gy, p = 0.004) and V17 Gy (21.5% ± 26.9% vs 25.0% ± 27.2%, p = 0.002) significantly decreased using IMRT compared with 3DCRT. IMRT plans showed a better target coverage compared with 3DCRT (0.91 ± 0.05 vs 0.93 ± 0.04, p = 0.05). Comparing the two different EBRT techniques, we demonstrated few, although substantial, dosimetric differences in terms of doses to the organs at risk characterized by a statistically significant dose reduction of LADCA in the IMRT plans. Elderly patients with a low compliance to treatment might benefit from 3DCRT with field-in-field tangential arrangement or from a simple IMRT approach. IMRT should be preferred.