Effectiveness of sentinel lymph node intraoperative examination in 753 women with breast cancer: are we overtreating patients?

OBJECTIVE

The goal of our study was to evaluate the sensitivity and specificity of sentinel lymph node biopsy (SLNB) frozen section (FS) examinations to detect metastatic lymph nodes and also its potential role in avoiding unnecessary demolitive axillary surgery.

BACKGROUND

SLNB is the standard of care in surgical oncology of the breast. Intraoperative evaluation of the SLN seems to achieve sufficient sensitivity for macrometastasis (Ma), leading to axillary lymph node dissection (ALND) only when strictly necessary. Is it equally as clear when to perform ALND if micrometastasis (Mi) or isolated tumor cells (ITCs) are detected?

METHODS

All consecutive patients from January 2005 to September 2010 operated on for breast cancer were prospectively enrolled. All patients underwent an FS SLNB. The sensitivity and specificity of SLN FSs in detecting Ma, Mi, and ITCs was calculated. All patients with Ma or Mi at FS underwent ALND. For all patients who underwent ALND, the number of metastatic non-SLNs was recorded and correlated to the size of the SLN metastasis.

RESULTS

A total of 753 patients were enrolled. FS examination had an overall 54% sensitivity and 100% specificity in detecting metastatic disease (Ma/Mi/ITCs). The sensitivity rises to 89% if only Mas were considered and to 64% if Mas and Mis were counted together. All patients with Mas or Mis detected at FS had a completion ALND during the same procedure (156/222). All patients with Mas detected at final pathology (16 false negatives, 2.6%) and 50 women with Mis or ITCs (119 false negatives, 20%) underwent a delayed ALND. When Mis or ITCs were detected in the SLN, only 8 of 73 (10.9%) and none of 4 (0%) patients, respectively, had at least 1 metastatic non-SLN after ALND. Two patients (2/460, 0.43%) who had negative SLNs showed local axillary recurrence. After a mean follow-up of 32 months, none of the 71 patients with Mis or ITCs who did not undergo a second operation showed local recurrence.

CONCLUSIONS

SLNB FS is highly effective in detecting the subgroup of patients who may benefit from completion ALND during the same surgical procedure. The role of Mi/ITCs in the SLN(s) is still unclear, but our data lean toward a less aggressive surgical approach.