In a single-institution retrospective analysis reported in the Journal of Clinical Oncology, Naoum et al found that pathologic exploration of axillary soft tissue in patients with lymph node–positive breast cancer is a critical element in predicting disease outcome and in determining axillary management.
Study Details
The study involved data from 2,162 patients with primary lymph node–positive breast cancer treated at Massachusetts General Hospital between 2000 and 2020.
Patients were sorted into four groups on the basis of axillary pathology positive findings:
- Lymph node–positive only (n = 1,247)
- Lymph node–positive and extracapsular extension only (n = 538)
- Lymph node–positive and axillary soft tissue without extracapsular extension (n = 77)
- Lymph node–positive with both axillary soft tissue and extracapsular extension (n = 300).
The primary outcome measures were the 10-year locoregional failure, 10-year axillary failure, and 10-year distant metastasis rates.
Key Findings
Median follow-up was 9.4 years (interquartile range = 5.5–14 years).
The 10-year locoregional failure rates were 6.2% for lymph node–positive only, 5.7% for lymph node–positive and extracapsular extension only, 10% for lymph node–positive and axillary soft tissue without extracapsular extension, and 14% for lymph node–positive with both axillary soft tissue and extracapsular extension.
The 10-year axillary failure rates were 1.6% for lymph node–positive only, 0.8% for lymph node–positive and extracapsular extension only, 4.6% for lymph node–positive and axillary soft tissue without extracapsular extension, and 4.5% for lymph node–positive with both axillary soft tissue and extracapsular extension.
The 10-year distant metastasis rates were 13% for lymph node–positive only, 23% for both lymph node–positive and axillary soft tissue without extracapsular extension and lymph node–positive and extracapsular extension only, and 42% for lymph node–positive with both axillary soft tissue and extracapsular extension.
On multivariate analysis, positive axillary soft tissue was associated with significantly increased risk of locoregional failure (hazard ratio [HR] = 2.3, P < .001), axillary failure (HR = 3.3, P = .003), and distant metastasis (HR = 1.6, P < .001).
In subgroup analyses, regional lymph node radiation improved locoregional failure rates with positive axillary soft tissue or extracapsular extension (HR = 0.5, P = .03). A dose of ≤ 50 Gy to the axilla with positive axillary soft tissue or extracapsular extension increased risk of axillary failure (HR = 3.0, P = .04). When regional lymph node radiation was given, axillary lymph node dissection could be de-escalated to sentinel node biopsy—even with positive axillary soft tissue or extracapsular extension—without increasing risk of locoregional failure (HR = 1.0, P = .92), axillary failure (HR = 1.1, P = .94), or distant metastasis (HR = 0.4, P = .01).
The investigators concluded, “Routine reporting of axillary tissue involvement, beyond lymph nodes and extracapsular extension, is crucial in predicting breast cancer outcomes. Ruling out the presence of axillary soft tissue is imperative before any form of axillary de-escalation, especially regional lymph node radiation omission.”
Alphonse G. Taghian, MD, PhD, FASTRO, of the Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, is the corresponding author for the Journal of Clinical Oncology article.
Disclosure: For full disclosures of the study authors, visit ascopubs.org.
