Retrospective analysis of sentinel lymph node biopsy using methylene blue dye for early breast cancer

Methylene blue is the most commonly used tracer for sentinel lymph node (SLN) biopsy (SLNB) in China. This study aimed to investigate the feasibility of clinical application of SLNB using methylene blue dye (MBD) for early breast cancer and the prognosis of patients with different SLN and non-SLN statuses.

We retrospectively analyzed the clinicopathological data of patients with early breast cancer treated at the Peking University First Hospital between 2013 and 2018. We calculated the SLN identification rate (IR) in SLNB with MBD and the false-negative rate (FNR), and analyzed the prognosis of patients with different SLN and non-SLN statuses using Kaplan-Meier curves.

Between January 2013 and December 2018, 1603 patients with early breast cancer underwent SLNB with MBD. The SLN IR was 95.8% (1536/1603). Two SLNs (median) were detected per patient. There were significant differences in FNR between patients with SLN micrometastasis and macrometastasis (19.0% vs. 4.5%, χ2 = 12.771, P < 0.001). Chi-square test showed that there were significant differences in SLN successful detection rates among patients with different vascular tumor embolism status (96.3% vs. 90.8%, χ2 = 9.013, P = 0.003) and tumor (T) stages (96.6% vs. 94.1%, χ2 = 5.189, P = 0.023). Multivariate analysis showed that vascular tumor embolism was the only independent factor for SLN successful detection (odds ratio: 0.440, 95% confidence interval: 0.224-0.862, P = 0.017). Survival analysis showed a significant difference in disease-free survival (DFS) between patients with non-SLN metastasis and patients without non-SLN metastasis (P = 0.006).

Our single-center data show that, as a commonly used tracer in SLNB in China, MBD has an acceptable SLN IR and a low FNR in frozen sections. This finding is consistent with reports of dual tracer-guided SLNB. Positive SLNs with non-SLN metastasis are associated with DFS.