Superiority of Pathologic Lymph Node Ratio over Positive Lymph Node Count in Operated Early-Stage Breast Cancer.

AIM

In early-stage breast cancer, the axillary lymph nodes play a crucial role in determining the prognosis of the disease. The rate of lymph node involvement might be a more valuable prognostic factor than the number of positive lymph nodes. Therefore, we aimed to evaluate whether the lymph node ratio (LNR) is a superior prognostic indicator compared to the pathologic lymph node count in early-stage disease.

METHODS

We included 3053 non-metastatic, lymph node-positive breast cancer patients who were treated and followed at 6 medical oncology centers in Türkiye between 2004-2018. Based on LNR, patients were classified into three risk groups: high (>0.65), intermediate (0.21-0.65), and low (≤0.20).

RESULTS

Classification of patients according to the TNM8 system based on the number of positive lymph nodes revealed that pathologic lymph node count (pN)1 accounted for 49.0% (n = 1495), pN2 for 30.0% (n = 917), and pN3 for 21.0% (n = 641). Based on the LNR risk group, the low-risk group accounted for 45.4% (n = 1385), intermediate for 36.2% (n = 1105), and high for 18.4% (n = 563) of the total patients. For the entire patient cohort, the 5- and 10-year disease-free survival (DFS) were 93% and 67%, respectively, while overall survival (OS) rates were 95% and 75%, respectively. The median DFS for patients with N1, N2, and N3 disease was 149 months (94.2-203.7), 120.1 months (108.2-132.0), and 81.8 months (68.4-131.1), respectively (p < 0.001). The median DFS for the three LNR risk groups (low, intermediate, and high risk) was 148.9 months (95.3-202.6), 118.7 months (99.9-137.7), and 81.8 months (68.2-95.3) respectively. Increasing LNR rate was an independent prognostic factor for DFS, according to multivariate analysis (p < 0.001). Furthermore, the median DFS was 133 months for pathologic N1 patients in the LNR intermediate-high risk group, while the median DFS was not reached in patients with LNR and the pN2 low risk group (p = 0.034).

CONCLUSIONS

This study confirms the significance of LNR as a prognostic factor for DFS. The results show that in certain specific subgroups, LNR provides more information than pathologic lymph node counts.