Axillary Irradiation with High Tangent Fields for Clinically Node-Negative Breast Cancer: Can 3-D Conformal Radiotherapy with a Field-in-Field Technique Better Control the Axilla?

Abstract

Background: The target volume for postoperative breast irradiation is the remaining breast tissue, and the axillary region is not an intentional target volume. Patients and Methods: Between 2001 and 2009, eligible women with pT1-2cN0/pN0(sn) breast cancer underwent breast-conserving therapy without axillary dissection. Treatment outcomes between 2 radiotherapy planning groups, high tangent fields with 2-dimensional (2-D) simulation-based planning and 3-dimensional (3-D) computed tomography-based planning with a field-in-field technique, were compared. The correlating factors for axillary failure were also calculated. Results: In total, 678 patients were eligible. As of May 2009, the median follow-up times for the 2-D (n = 346) and 3-D (n = 332) groups were 94 and 52 months, respectively. Patient characteristics were balanced, except for a younger population in the 2-D group and more lymphovascular invasion in the 3-D group. On multivariate analysis, 2-D planning was the only risk factor for axillary failure. In the 2-D and 3-D groups, the 5-year cumulative incidences of axillary failure were 8 (3.1%) and 1 (0.3%) (log-rank p = 0.009), respectively. The respective 5-year overall survival rates were 97.4 and 98.4% (p = 0.4). Conclusion: High tangent irradiation with 3-D planning improved axillary control compared to that with 2-D planning, suggesting that optimizing axillary dose distribution may impact outcomes.

St. Gallen/Vienna 2015: A Brief Summary of the Consensus Discussion

“…Great emphasis was again given to locoregional treatment aspects, with observations that surgery is being further minimized but radiotherapy appears to be becoming more aggressive [4], and surgical tactics do not change much after neoadjuvant therapy. The impact of a rising number of molecular testing tools was assessed, both for judging prognosis of early and late metastasis risk, but also for prediction of therapy benefit.…”

Effect of hypofractionation on the incidental axilla dose during tangential field radiotherapy in breast cancer

“…Hence the degree of incidental lymph node irradiation varied between the patients from 12.1 ± 19.2% of the prescribed dose (patient III) to 64.8 ± 17.8% of the prescribed dose (patient II). Differently from our study, most previous studies estimated the dose distribution in the lymph node areas as defined by RTOG or ESTRO guidelines [ 5 , 6 , 9 , 11 , 24 , 25 ]. However, these guidelines define a treatment volume and do not necessary reflect the whole axillary lymph node drainage system and both primary lymph node metastases and lymph node recurrences occur outside the ESTRO and RTOG margins [ 16 , 26 ].…”

“…Current guidelines recommend the omission of ALND in case of 1) negative SLNB, 2) micrometastases seen in SLN, or 3) 1–2 positive lymph nodes and T1–2 tumors after BCS without preoperative chemotherapy and planned whole-breast RT [ 5 ]. According to these recommendations, residual tumor cells in the axillary lymph nodes must be expected in a relevant number of patients prior to whole-breast irradiation.…”

“…Several previous studies focused on the dose distribution in the axillary levels during tangential field irradiation [5][6][7][8].The dose distribution varies largely depending on patient anatomy and treatment technique (e.g., high tangent vs. conventional tangent). Usually, a smaller dose per fraction compared to the prescribed dose is delivered to the axillary lymph node areas [9].…”

High Tangent Radiation Therapy With Field-in-Field Technique for Breast Cancer

“…There was no significant difference in doses to the breast between 2D and 3D-based plans. Sanuki et al 21 reported that the 3D-based HTRT improved axillary control compared with 2D-based HTRT.…”