Moving from 2D to 3D-CRT Planning of Chest Wall for Postmastectomy Breast Cancer Patients: Mansoura University Experience

Background: This study evaluates the dose distribution of the wedged tangential beam three-dimensionally planned conformal radiotherapy (3D-CRT) compared to the previously used (5 years ago) two-dimensionally (2D-RT) planned radiotherapy of the chest wall for postmastectomy breast cancer patients in Clinical Oncology and Nuclear Medicine Department, Mansoura University. Patients and Methods: Thirty six unselected breast cancer patients were planned by both the standard 3D-CRT and 2DRT techniques for radiotherapy of the chest wall. Dose-volume histograms were carried out by the 3D treatment planning system. They were assessed for the PTV and organs at risk. The prescribed total dose was 50Gy in 25 fractions. Results: The three-dimensionally planned conformal radiotherapy showed an improvement of the PTV coverage and statistically significant better in homogeneity index of the chest wall (p<0.001). The ipsilateral mean lung dose was significantly reduced with the tangential beam 3D-CRT plans with an average of 24.6% (1217cGy versus 1614cGy). For the left sided breast cancer patients, the mean heart dose was also reduced by an average of 48.6% (718cGy versus 1398cGy). The mean percentage dose of the contralateral breast to the prescribed dose was 8.2% for 3D-CRT, compared with 10.4% for 2D-RT tangential field techniques. Conclusions: The tangential beam 3D-CRT planning demonstrated a significantly better homogeneity index for the PTV of the post-mastectomy breast cancer patients with a significant reduction in the mean doses of the ipsilateral lung and the heart for the left-sided breast cancer patients.