Lymph node ratio and pN staging in patients with node-positive breast cancer: a report from the Korean breast cancer society

Abstract

Patients with node-positive breast cancer are currently classified according to pN stage. Lymph node ratio (LNR), the ratio of positive to total removed lymph nodes, maybe a more useful prognostic factor in these patients. We therefore compared LNR and pN staging as prognostic factors in patients with node-positive breast cancer. Using two large prospective databases of the Korean Breast Cancer Registry (KBCR) and the Asan Medical Center (AMC) Breast Cancer Center of patients with LN-positive breast cancer from 1988 to 2005, we compared the ability of LNR and pN stage to predict patient survival by Cox regression analysis in the overall patient cohort and in subgroups categorized by age and intrinsic subtype. Patients were categorized into low- (≤ 0.20), intermediate- (>0.20 and ≤ 0.65), and high-risk (>0.65) LNR groups. The difference in mortality risk was greater among LNR groups than among patients staged pN1, pN2, and pN3, as assessed by disease-free survival (DFS), cancer-specific survival (CSS), and overall survival (OS) rates. In contrast to LNR risk categories, the survival curves for pN1 and pN2 stage patients overlapped in those aged <35 years and those with her2/neu-enriched or triple-negative tumors. These findings were validated by analyzing a nationwide registry of 15,488 node-positive patients, which showed that patients with pN1 and intermediate LNR risk had poorer DFS (HR 1.7, 95% CI 1.4-2.2) and CSS (HR 1.6, 95% CI 1.1-2.2) than patients with pN2 and low LNR risk. LNR is a better predictor of prognosis than pN stage in women with breast cancer, especially in high-risk patients, including younger women and women with her2/neu-enriched or triple-negative tumors. Treatment decisions should be based on LNR rather than on pN stage.

Breast Cancer—Major changes in the American Joint Committee on Cancer eighth edition cancer staging manual

“…The expert panel considered but decided not to incorporate the lymph node ratio (LNR) as an alternative method for N classification and recognized that, when modest numbers of lymph nodes are removed for pathologic evaluation, the LNR performs as well or better than total positive lymph nodes for outcome prediction. [6][7][8][9] However, when only a few lymph nodes are removed, which commonly occurs with sentinel lymph node biopsy, the LNR can perform worse than total positive lymph nodes and may be misleading.…”

Clinical Significance of Lymph Node Ratio in Locally Advanced Breast Cancer Molecular Subtypes

“…The ratio of metastatic to dissected lymph nodes was shown to be a more sensitive and superior prognostic factor than the classical AJCC staging system [11,12,13,14,15]. In the present study, the LNR and other prognostic factors were examined with respect to tumor molecular subtype, and the relationship of these factors to survival rates were investigated in BC patients.…”

“…In this situation, the AJCC lymph node staging system can lead to heterogeneous results. To avoid this confusion, research efforts have focused on implementing another metric, the ratio of metastatic to total dissected lymph nodes (lymph node ratio; LNR), which has proven to be a more sensitive and superior prognostic factor than the total number of involved lymph nodes [11,12,13,14,15]. To our knowledge, no studies have evaluated the relationship between LNR and molecular subtypes in BC.…”

A proposal for a new classification of T4 breast cancer as stage IIIC: a report from the Korean Breast Cancer Society

“…A new staging system, which incorporates grade and estrogen receptor status, has been suggested [15] and lymph node ratio, which is the ratio of metastatic lymph nodes to harvested lymph nodes, as a substitute for N stage is still being debated [16,17]. The ability to diagnose cancer early, to characterize tumors, to assess disease extent, and to treat improves every year.…”