Diagnostic value of intraoperative examination of sentinel lymph node in early cervical cancer: a prospective, multicenter study

Objectives: Sentinel lymph node (SLN) biopsy is a surgical procedure proposed in early cervical cancer. This technique yields the potential interest to reduce the morbidity of complete lymphadenectomy, which could then be performed only in case of positive SLN. Intraoperative examination has a major per-operative role in predicting nodal involvement and preventing a second step procedure. The aim of this study was to assess the diagnostic value of intraoperative examination with frozen section (FS) or imprint cytology (IC) of SLNs in early cervical cancer.

Methods: Prospective study in 7 centers (01/2005-06/2007) including patients with stage IA1 and lymphovascular space involvement to IB1 cervical cancer (squamous cell carcinoma, adenocarcinoma or adenosquamous carcinoma). SLNs were detected with a combined method (Tc99m+blue dye) and then removed laparoscopically. Intraoperative examination (FS or IC) was not systematically performed but recommended in case of macroscopical nodal enlargement in 5 centers. Results of intraoperative examination were compared with final histology performed by Hematoxylin-Eosin-Safran staining and immunohistochemistry. The diagnostic value of intraoperative examination was calculated.

Results: One hundred and thirty-nine patients were analyzed in the study. The combined detection rate was 97.8% per patient, with 454 detected SLNs. One hundred and two patients (73.4%) had an intraoperative examination (97 patients with FS and 5 with IC). Among patients with intraoperative examination, 5 SLNs were positive (all with macrometastasis at final histology), as compared with 22 metastatic nodes at final result. The 17 false negative SLNs were: 4 macrometastasis, 4 micrometastasis and 9 isolated tumor cells. Sensitivity of the intraoperative examination per node was 20.7% [95%CI: 7.8%-45.4%] and the negative predictive value 93.0% [95%CI: 89.0%-95.9%].

Conclusions: Intraoperative examination of SLNs by FS and IC has a poor diagnostic value. This is mainly related to micrometastasis and isolated tumor cells, which are not detected by intraoperative techniques. Other techniques, like new molecular assays, should be investigated to improve intraoperative assessment of SLNs.