Introduction/Background The axillary region is considered problematic; a risked organ (OAR), a predictive dosimetric parameter of long-term lymphedema, and a residual-disease site in case of breast-cancer radiotherapy.Our study endeavors to determine the dose received by the axillary area in adjuvant radiotherapy for breast-cancer and to assess its clinical impact on long-term lymphedema.

Methodology A retrospective dosimetric study, executed in the radiotherapy department of Farhat Hached Hospital, Sousse, included 50 female patients treated with three-dimensional adjuvant radiotherapy for breast-cancer, between 2018 and 2019. The axillary-area was delineated according to the European-Organization for Research and Treatment of Cancer(EORTC) guidelines.

Results The average age was 52[30–80]. 64% of our patients had a mastectomy with ipsilateral axillary lymph-node dissection(IALND), while 36% had a lumpectomy with a IALND. 35 patients(70%) received regional radiotherapy and 15 patients(30%) had only local radiotherapy with 2 tangential fields. All the patients were treated with normofractionated radiotherapy dose of 50Gy. Patients with conservative surgical treatment or T4 classified tumors received an additional boost; 66Gy (21patients) and 70Gy for tumoral-surgical limits (1patient). The mean axillary volume was 77.9 cm3[9.4–181]. The mean-dose, the maximal-dose and the minimal-dose received by the axillary region were respectively 28.49Gy[3.19–53.7Gy], 54.18Gy[33.96–72.63Gy] and 9.4Gy[0.32–10.74Gy].Late complications of lymphedema and radio induced dermatitis (GI and II according to the CTCAEV5.0scale) were observed respectively in 6(12%) and 17(34%) patients.

Conclusion To conclude, the axillary-area received unintentional and significant doses during breast-irradiation; by the tangential fields or the additional supraclavicular field. Some authors consider that the axillary-lateral thoracic vessel junction (ALTJ); that’s above level I Berg, as an OAR for long-term lymphedema and its dose can be minimized especially for clinically node-negative patients. Further validation of lymphedema OAR dosimetric parameters by prospective studies is justified.