Sentinel lymph node biopsy in early-stage cervical cancer: utility of intraoperative versus postoperative assessment

To determine the diagnostic accuracy of sentinel lymph node (SLN) detection using lymphoscintigraphy, intraoperative blue dye, and radiocolloid in patients with early-stage cervical cancer.

Intra-cervical injection of technetium-99 sulfur colloid and lymphoscintigraphy were performed preoperatively. Isosulfan blue was injected intra-cervically immediately prior to surgery. SLNs were excised and examined intraoperatively (imprint cytology and frozen section) and postoperatively (H and E histology and immunohistochemistry (IHC) for cytokeratin).

Thirty eight patients were evaluable. Laparoscopy and laparotomy were performed in 28.9% and 71.1%, respectively. Subjects had squamous cell carcinoma (n=26), adenocarcinoma (n=10) or adenosquamous (n=2) histologies. 55.3% had cervical tumors <2 cm. The overall SLN detection rate was 92.1%. The external iliac region just distal to the common iliac bifurcation was the most common SLN location. A mean of 2.1 SLNs were detected per patient with bilateral SLNs observed in 47.4%. On final pathology, metastatic nodal disease was identified in 15.7% of patients. Of these, 83.3% were detected in the SLNs. Sensitivity of SLN detection of metastasis was 100% for patients with cervical tumors <2 cm. However intraoperative evaluation by imprint cytology and frozen section correctly identified lymph node metastasis in only 33.3%.

SLN detection is feasible and accurately reflects pelvic nodal basin status when performed in early-stage cervical cancer patients. However, while current intraoperative pathology techniques for assessing nodal metastases reliably detect metastases larger than 2 mm, they lack sufficient sensitivity to detect micrometastasis and isolated tumor cells.