Comparison of survival outcomes between axillary conservation and axillary lymph node dissections in N1 early breast cancer: a propensity-matched SEER analysis.

Background: Sentinel lymph node dissection (SLND) is an alternative to axillary lymph node dissection (ALND) for breast cancer surgery. But the criteria of SLND only for patients with limited disease in the sentinel node is disputed.

Methods: From the Surveillance, Epidemiology, and End Results (SEER) database, 2000-2015, we identified 97,296 early breast cancer females with 1-3 axillary lymph nodes macro-metastasis. Of them, 1-5 (axillary conservation group), 6-9, and ≥ 10 (ALND group) axillary lymph nodes were dissected in 28,639, 16,838, and 51,819 patients, respectively. According to the criteria of the ACOSOG Z0011 trial, two historical cohort studies of patients who underwent lumpectomy or mastectomy were conducted and the survival outcomes between ALND and axillary conservation were compared.

Results: Overall, dissection of 6-9 regional lymph nodes resulted in the worst prognosis. After propensity-matched analysis, it was found that patients in the axillary conservation group had worse survival than the ALND group in overall survival. No significant difference in prognosis between the group undergoing lumpectomy was found both in OS and BCSS. Subgroup analysis revealed that Grade 3, T2, two lymph nodes positive, or Her2 positive were the main causes of worse survival in the axillary conservation group.

Conclusion: Not all patients with N1 early breast cancer suit axillary conservation. Axillary conservation was sufficient in patients who were treated with lumpectomy. ALND cannot be omitted in patients who were ineligible for the Z0011 and undergoing mastectomy with the following characteristics: T2, Grade 3, two positive lymph nodes, and Her2 positive, which may be better complemented to the Z0011 trial. Hence, under different surgical methods, the clinical precision treatment of ALND or axillary preservation is essential.