Axillary irradiation in breast cancer; does meticulous contouring make a difference?

Background: Due to the current trends towards replacing axillary dissection with radiotherapy, the need for more precise definition for different nodal stations becomes a must to ensure safe and adequate dose coverage. So, our study aimed to evaluate the coverage of axillary nodal volumes based on Project on Cancer of the Breast (PROCAB) guidelines, for cases previously treated with our standard tangential approach. Materials and Methods: Ten cases of previously treated patients diagnosed with breast cancer were included in this study. All patients were treated with three dimensional (3D) conformal radiotherapy. For each patient, a new contouring based on PROCAB guidelines were done for each lymph node (LN) station. An adequate dose coverage was assessed for all volumes using our Eclipse version 11 planning system. Results: From Jan. 2016 and March. 2016, ten patients who were pathologically confirmed to have breast cancer and treated at Kasr Alaini Centre of Clinical Oncology and Nuclear Medicine, Cairo University, Egypt were included. The mean volumes of axillary levels I, II, and III were 33.29 cm3 (range 18.6 – 54.8cm3), 13.27 cm3 (range 9.4–16.8 cm3), and 12.84 cm3 (range 7.9—18.2 cm3), respectively. Level I, II and III lymph nodes received a median D98% of 7.82 Gy, 9.54 Gy, and 22.54 Gy, respectively. The mean dose was 34.94 Gy, 33.64 Gy, and 39.79 Gy, respectively. Conclusion: PROCAB guidelines present a method for standardization of axillary LN delineation. More advanced radiotherapy planning is needed to improve coverage of axilla in post-operative treatment of breast cancer.