Value of sentinel node mapping in cancer of the cervix

ObjectivesTo compare the relative value of two methods of detection for the sentinel lymphatic nodes (SLNs): colorimetric with Isosulfan blue (ISB) and radio-isotopic with Technetium-99 (Tc99), and to evaluate the concept of the SLN mapping applied to cervical cancer.MethodsFrom October 2000 to December 2006, radical surgery was planned in 211 patients who presented early-stage cancer of the cervix. Both ISB and Tc99 were used to detect the SLNs. In all cases, we proceeded with laparoscopy for the identification and removal of the SLNs, followed by a complete pelvic lymphadenectomy with or without para-aortic node sampling. The SLNs were sent for frozen section (1 level) and were ultra-staged (6 levels) for final pathology. Detection rate, sensitivity and negative predictive value (NPV) were calculated.ResultsAmong the 211 patients, ISB (n = 152) identified at least 1 SLN in 92.8% of the cases. With Tc99 (n = 166), the detection rate of SLN increased to 96.9%. When both techniques were used together (n = 107), Tc99 was significantly better than ISB by 7.8% (p = 0.0094) and at least 1 SLN (hot and/or blue) was found in 99.1% of the cases. In 16.7% of patients, a SLN was located in aberrant sites, including 3.8% in the para-aortic area. Thirty-three out of the 211 patients (15.6%) had lymph node metastases. When considering only the 181 patients with bilateral SLNs identified, the NPV of SLN is 100% after ultra staging on final pathology and 94.2% on frozen section (FS).ConclusionSentinel node mapping is feasible using laparoscopy. The radio-isotopic technique adds significantly to the rate of detection. The main benefits of SLN mapping in cervical cancer are the detection of micro-metastases on ultra staging which might be missed on routine pathological evaluation, and identification of aberrant drainage sites. However, the current frozen section techniques lack sensitivity to identify very small metastases and need refinement. SLN mapping should become the standard of care in the modern management of cervical cancer and complete pelvic lymphadenectomy could be avoided when bilateral SLNs are detected in patients with lesions less than 2 cm.

Research highlights
► With ISB and/or Tc99, bilateral SLNs were identified in 85% of patients.
► In 16%, a SLN was found outside the usual field of pelvic lymphadenectomy.
► Ultrastaging identified micrometastases in 10 patients with negative FS.