Comparison of Nodal Target Volume Definition in Breast Cancer Radiation Therapy According to RTOG Versus ESTRO Atlases: A Practical Review From the TransAtlantic Radiation Oncology Network (TRONE)

Abstract

Regional nodal irradiation has gained interest in recent years with the publication of several important randomized trials and the availability of more conformal techniques. Target volume delineation represents a critical step in the radiation planning process. Adequate coverage of the microscopic tumor spread to regional lymph nodes must be weighed against exposure of critical structures such as the heart and lungs. Among available guidelines for delineating the clinical target volume for the breast/chest wall and regional nodes, the Radiation Therapy Oncology Group and European Society for Radiotherapy and Oncology guidelines are the most widely used internationally. These guidelines have been formulated based on anatomic boundaries of areas historically covered in 2-dimensional field-based radiation therapy but have not been validated by patterns-of-failure studies. In recent years, an important body of data has emerged from mapping studies documenting patterns of local and regional recurrence. We aim to review, discuss, and compare contouring guidelines for breast cancer radiation therapy in the context of contemporary data on locoregional relapse to improve their implementation in modern practice.

Can the Choice of Radiotherapy Delivery Technique Influence Which Target Delineation Protocol to Use? A Plan-Quality-Based Analysis in Left Breast Cancer

“…Data on regional nodal failures stratified by delineation protocols is now emerging, and while our analysis was not designed to assess the quality of regional nodal irradiation, this is an important avenue for research and our group will be addressing it in the near future. 25 Our analysis shows that if a particular planning technique is preferred, some thought should be given to the delineation protocol best suited for it. At this time, in the absence of a local control analysis, it is impossible to decide whether ESTRO or RTOG delineation guidelines should be followed, and until such a report appears, radiation oncologists can choose either.…”

PET/CT of breast cancer regional nodal recurrences: an evaluation of contouring atlases

“…They concluded that more generous CTVs may be recommended for patients with locally advanced disease. Loganadane et al also compared the nodal target volumes of the RTOG, ESTRO and RADCOMP atlases [36]. They provided detailed visual and written details about the differences between the atlases and concluded that treatment planning for patients with locally advanced disease should use the RADCOMP atlas.…”

Tricks and tips for target volume definition and delineation in breast cancer: Lessons learned from ESTRO breast courses

“…A comparison between the two different approaches has been performed by a few groups and this has included mapping of location of recurrences. For some components of nodal target volumes, ESTRO volumes tend to be larger than RTOG volumes as a result of the ESTRO recommendation of adding a 5 mm margin lateral and medial (cropping the volume onto the lung surface) to the internal mammary vessels, and adding a volume to interpectoral nodal CTVn between the pectoralis major and minor [28][29][30][31]. Conversely, ESTRO volumes tend to be smaller at CTVn_level 1 toward the arm and back muscles and the CTVn_level 4 where the cranial border is reduced from the cricoid cartilage to 5 mm cranial to the subclavian vein.…”