Breast

Objective: Conventional field radiotherapy based on anatomical landmarks has been the traditional treatment for breast cancer. Having proven efficacy it is still the current standard of treatment. The Radiation Therapy Oncology Group (RTOG) has published guidelines for contouring target volumes in postmastectomy patients. The impact of this guideline in current clinical practice is less known hence we have analyzed dose-volume histograms (DVHs) for these plans and compared them with the proposed treatment plans to treat RTOG-defined targets. Materials and Methods: RTOG consensus definitions were used to contour the target volumes in 20 previously treated post-mastectomy patients. The prescription was 42.4 Gy in 16 fractions. DVHs were generated from clinically designed plans that had actually been delivered to each patient. For comparing dose to target volumes, new plans were generated with the goal of covering 95% of volume to 90% of prescribed dose. Results: In RTOG contoured Group, coverage improved for the SCV (V90 = 83 versus 94.9%, P < 0.05) and CW (V90 = 89.8 versus 95.2%, P < 0.05). Axillary nodal coverage improved for Level-1 (V90 = 80.35 versus 96.40%, P < 0.05), Level-II (V90 = 85.93 versus 97.09%, P < 0.05) and Level III (V90 = 86.67 versus 98.6%, P < 0.05). The dose to the ipsilateral lung is increased (V20 = 23.87 versus 28.73%, P < 0.05). Low dose to heart is increased in left sided cases (V5 = 14.52 versus 16.72%, P < 0.05) while same in right sided cases. Conclusions: The study shows that radiotherapy using the RTOG consensus guidelines improves coverage to target volumes with a nonsignificant increase in normal organ dose compared to that based on anatomical landmarks.