The following is a summary of “Pathologic Exploration of the Axillary Soft Tissue Microenvironment and Its Impact on Axillary Management and Breast Cancer Outcomes,” published in the November 2023 issue of Oncology by Naoum, et al.

For a study, researchers sought to emphasize the importance of evaluating axillary soft tissue (AXT) involvement, particularly when tumor cells extend beyond the positive lymph node (LN+) and show extracapsular extension (ECE) during breast pathology specimen analysis.

A comprehensive analysis was conducted on 2,162 LN+ patients. These patients were segmented into four distinct groups based on their axillary pathology: those with LN+ only, those with LN+ and ECE only, those with LN+ and AXT without ECE, and finally, those with LN+ accompanied by both AXT and ECE. The study primarily focused on assessing three main outcomes over 10 years: locoregional failure (LRF), axillary failure, and distant metastasis rates. The study adjusted for various clinical factors using multivariable Cox models and further conducted subgroup analyses for more specific insights.

Upon analyzing the data with a median follow-up duration of 9.4 years, distinct patterns emerged concerning the outcomes. Notably, the 10-year distant metastasis rates varied significantly across groups: 42% for patients with LN + AXT + ECE, 23% for those with both LN + AXT and LN + ECE only, and a lower 13% for the LN+ only group. Similarly, the 10-year axillary failure rates showed variations, with the LN + AXT + ECE group at 4.5%, LN + AXT at 4.6%, LN + ECE only at 0.8%, and LN+ only at 1.6%. The multivariable analysis highlighted the significant association of AXT with distant metastasis, locoregional failure, and axillary failure. Further subgroup analyses highlighted that regional LN radiation (RLNR) offered better locoregional tumor outcomes in cases where AXT, ECE, or both were present. However, caution was advised as delivering ≤50 Gy to the axilla in the presence of AXT or ECE increased the risk of axillary failure. Intriguingly, the study found that when employing RLNR, it was feasible to reduce axillary LN dissection to a sentinel node biopsy, even with AXT or ECE features, without a notable rise in failure outcomes.

In conclusion, the meticulous reporting of AXT involvement beyond LNs and ECE is paramount for accurately predicting breast cancer outcomes. Before contemplating any form of axillary de-escalation, especially the omission of RLNR, ensuring the absence of AXT becomes imperative based on the study’s findings.

Source: ascopubs.org/doi/10.1200/JCO.23.01009