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

Background: Elderly breast cancer patients are frequently affected by significant comorbidities that make sophisticated radiotherapy treatments particularly challenging. Aims: 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. Methods: 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. Results: 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). Discussion: 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. Conclusions: 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.