Background: Breast cancer sentinel lymph nodes (SLNs) with metastases (mets) are often palpably enlarged. We hypothesized that the volume of the SLN and the size of mets are directly related. SLNs harboring mets are often firm, with increased intra-nodal pressure (INP), and we hypothesized that SLN volume, as well as INP, would correlate directly with SLN metastasis size.
Methods: The SLN volume, INP and met size were measured in 296 SLNs and compared using linear regression analysis. The SLNs were subsequently grouped based upon pN stage. SLN INP and volume were compared between these resultant groups.
Results: Increased SLN volume significantly predicted increased SLN met size on univariate and multivariate analysis (p = 0.001 and p = 0.011, respectively). SLN met size predicted increased SLN INP on both univariate and multivariate analysis (both p = 0.001). SLN volume only significantly correlated with increased SLN INP on univariate analysis (p = 0.001). On subgroup analysis of nodal disease, pN1/2/3 nodes (SLN met sizes >2 mm) were significantly larger (p = 0.039 and p = 0.003, respectively) than pN0 and pN1(mi) nodes, and had significantly increased INP (all p = 0.001) as compared to pN0, pN0(i+), and pN1(mi) nodes.
Conclusions: SLN volume and INP increased with increasing SLN met size. The threshold met size for this increase was >2 mm (pN1 disease).
Keywords: Breast cancer; Metastasis; Pressure; Sentinel lymph node; Volume.
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