Axillary intranodal pressure measurement: A complementary technique for detection of lymph node metastasis in breast cancer patients

Background: There is growing evidence that intranodal pressure (INP) can predict metastatic sentinel lymph nodes (SLNs). The objective of this study was to measure and utilize INP to evaluate the metastatic involvement of axillary SLNs in breast cancer patients. Materials and Methods: INP was measured in 73 clinically node-negative (cN0) breast cancer patients who were candidate for SLN biopsy. Clinical evaluation of the lymph node, coupled with frozen section analysis of the same excised SLN, was conducted. The level of suspicion (LOS) was used to assess the likelihood of metastases in the SLNs by the surgeons. Then, the miniature catheter tip pressure transducer was used to measure INP in the operation room. Finally, excised SLN was sent for permanent pathologic analysis as a gold standard for the evaluation of SLNs metastatic.Results: We identified the statistically significant increase in INP in nodes containing tumor metastasis in comparison with tumor-free SLNs (19.17 ± 13.63 vs. 8.82 ± 4.23) (P = 0.003). We considered the cutoff value for INP at 16 mmHg, which resulted in sensitivity of 80% and specificity of 87%. When the combination of INP above 16 mmHg and the LOS were taken into account for determining the likelihood of metastatic involvement of the LNs, the sensitivity and specificity were 87.5% and 91.7%, respectively. Conclusion: Our data suggest that INP measurement has the potential to help surgeons differentiate metastatic and nonmetastatic SLNs in combination with LOS. Meanwhile, it can be used along with frozen analysis to decrease false-negative rate.