# Contouring Guidelines for the Axillary Lymph Nodes for the Delivery of Radiation Therapy in Breast Cancer: Evaluation of the RTOG Breast Cancer Atlas.

**Autores:** Gentile Michelle S, Usman Asad A, Neuschler Erin I et al
**Revista:** Int J Radiat Oncol Biol Phys (2015)
**PMID:** 26383674 | **PMCID:** PMC12422023
**DOI:** [10.1016/j.ijrobp.2015.07.002](https://doi.org/10.1016/j.ijrobp.2015.07.002)
**Fuente:** PubMed Central (open access)

## Relevancia
Estudio retrospectivo (N=30) sobre conversión nodal post-NAC. Implicaciones para radioterapia regional post-NAC según respuesta nodal.

## Abstract
The purpose of this study was to identify the axillary lymph nodes on pretreatment diagnostic computed tomography (CT) of the chest to determine their position relative to the anatomic axillary borders as defined by the Radiation Therapy Oncology Group (RTOG) breast cancer atlas for radiation therapy planning.

Pretreatment diagnostic CT chest scans available for 30 breast cancer patients with clinically involved lymph nodes were fused with simulation CT. Contouring of axillary levels I, II, and III according to the RTOG guidelines was performed. Measurements were made from the area of distal tumor to the anatomic borders in 6 dimensions for each level.

Of the 30 patients, 100%, 93%, and 37% had clinical involvement of levels I, II, and III, respectively. The mean number of lymph nodes dissected was 13.6. The mean size of the largest lymph node was 2.4 cm. Extracapsular extension was seen in 23% of patients. In 97% of patients, an aspect of the involved lymph node lay outside of the anatomic border of a level. In 80% and 83% of patients, tumor extension was seen outside the cranial (1.78 ± 1.0 cm; range, 0.28-3.58 cm) and anterior (1.27 ± 0.92 cm; range, 0.24-3.58 cm) borders of level I, respectively. In 80% of patients, tumor extension was seen outside the caudal border of level II (1.36 ± 1.0 cm, range, 0.27-3.86 cm), and 0% to 33% of patients had tumor extension outside the remaining borders of all levels.

To cover 95% of lymph nodes at the cranial and anterior borders of level I, an additional clinical target volume margin of 3.78 cm and 3.11 cm, respectively, is necessary. The RTOG guidelines may be insufficient for coverage of axillary disease in patients with clinical nodal involvement who are undergoing neoadjuvant chemotherapy, incomplete axillary dissection, or treatment with intensity modulated radiation therapy. In patients with pretreatment diagnostic CT chest scans, fusion with simulation CT should be considered for tumor delineation.

## Acceso
Disponible en PMC: https://pmc.ncbi.nlm.nih.gov/articles/PMC12422023/

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*Datos de PubMed. Citar: doi 10.1016/j.ijrobp.2015.07.002*
