Abstract 160P
Background
Since the American College of Surgeons Oncology Group Z0011 and RxPONDER results, the significance of axillary lymph node (LN) metastases in surgery and systemic therapy has been decreasing in certain breast cancer patients. The purpose of our study was to determine whether it would be possible to omit axillary surgery in patients with clinically LN negative (cN0), postmenopausal ER+HER2- breast cancer who perform breast-conserving surgery (BCS).
Methods
We retrospectively identified 376 patients with postmenopausal, ER+HER2- breast cancer who perform BCS in two hospitals from January 2003 to December 201, and 333 patients with cN0 were selected. The proportion of patients who actually had LN metastasis and the number of metastatic LN were confirmed. The risk factor of LN metastasis was analyzed using a binary logistic model. Disease-free survival (DFS) was compared applying the Kaplan-Meier survival curve.
Results
Among cN0 patients, LN metastasis was confirmed by axillary surgery in 24.3% of patients. Pathologic tumor size and lympho-vascular invasion (LVI) were the risk factors for LN metastasis (pathologic tumor size: odd ratio [OR], 2.17; 95% confidence interval [CI], 1.17–4.02; P=0.014; LVI: OR, 2.99; 95% CI, 1.56–5.72; P=0.001). However, patient with ≥3 LN metastases accounted for only 4.5% of all patients. In multivariate analysis, pathologic tumor size was the risk factor for ≥3 LN metastases (OR, 3.82; 95% CI, 1.27–11.53; P=0.017). There were in 3.1% of pT1 patients and 9.2% of pT2 patients (P=0.024). DFS was not statistically different between patient with and without ≥3 LN metastases (P=0.442).
Conclusions
The proportion of ≥3 LN metastases in cN0, postmenopausal ER+HER2- patients who perform BCS was low, and there was difference depending on the pathologic tumor size. Therefore, in patients with pT1, the omission of axillary surgery such as SLNB could be carefully considered. A large-scale prospective trial will be necessary in the future.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Hallym University Research Fung 2021 (HURF-2021-202104300001).
Disclosure
All authors have declared no conflicts of interest.