Minimal prognostic significance of sentinel lymph node metastasis in patients with cT1–2 and cN0 breast cancer

BACKGROUND: The prognostic value of sentinel lymph node (SLN) metastases may be minimized by the limited disease burden of lymph node metastases and tailoring adjuvant therapy based on breast cancer biology. The aim of this study is to assess the prognostic significance of SLN metastasis in patients with cT1–2N0M0 breast cancer. PATIENTS AND METHODS: Between January 2006 and December 2015, 582 patients underwent SLN biopsy for cT1–2N0M0 breast cancers. cN0 was essentially diagnosed by ultrasound sonography. The prognostic values of SLN metastases were retrospectively evaluated. RESULTS: Among 582 patients with cT1–2N0M0 breast cancer, 111 patients (19.1%) were positive for SLN metastasis, including 39 cases (6.7%) of micrometastasis and 72 cases (12.4%) of macrometastases. The median size of SLN metastasis was 3.0 mm (range 0.2–16 mm, mean 4.1 mm). In log-rank test, presence of SLN metastasis was not associated with breast cancer recurrence (p = 0.21); 5-year and 10-year recurrence-free survival (RFS) were 93.0% and 96.5%, and 93.0% and 90.4% in the SLN-positive and SLN-negative groups, respectively. In the propensity score matching cohort (n = 178), there was no significant difference in RFS between the SLN-positive and SLN-negative groups (p = 0.90). In Cox regression analysis, a continuous value of Ki67 expression was a significant prognostic factor (HR 1.03; 95% CI 1.01–1.05, p = 0.017). CONCLUSION: SLN metastasis has a minimal impact on RFS for patients with cT1–2N0M0 breast cancer in the modern medical era. A proliferation marker is a better factor for poor prognosis than the presence of SLN metastases in this population. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12957-019-1585-9) contains supplementary material, which is available to authorized users.