A single institutional experience of factors affecting successful identification of sentinel lymph node in breast cancer patients.

Background: Sentinel lymph node biopsy (SLNB) has become the standard of care in axillary staging of clinically node-negative breast cancer patients. We hypothesized that certain clinical parameters are associated with failure to identify a SLN.

Methods: We performed an institutional review board-approved, retrospective analysis of 402 consecutive breast cancer patients who underwent SLNB from 2000 to 2007.

Results: Of 402 patients, 399 had lymphoscintigraphy (LSG) performed at the time of radiocolloid injection. No significant differences in successful identification of a SLN were found with respect to patient age, histology, or pathologic status of the SLN. Thirteen of 27 patients with no nodes imaged on LSG failed to have a SLN identified at surgery, whereas only 8 of 372 patients with positive imaging on LSG failed to have a SLN identified at surgery (P < .0001). Patients with a body mass index (BMI) > or =40 had a significantly higher rate of failure to detect a SLN by LSG (5/29 patients) compared with patients with a normal BMI (4/145 patients; P < .01). There was a trend for association with increasing BMI and failure to identify a SLN at surgery. The rate of failure to identify a SLN demonstrated a significant improvement in LSG after 200 patients and in surgical success after 100 patients (P < .001).

Conclusion: Successful identification of a SLN was influenced by BMI, institutional experience, and successful imaging by LSG. After gaining appropriate experience, the probability of successfully identifying a SLN at the time of surgery in a patient with BMI <40 who imaged on LSG was 99.7%.