Sentinel lymph nodes

In his recent editorial, Covens1 discussed the issues and the limitations of the reported sentinel lymph node (SN) procedure for patients with cervical carcinoma.2 The first issue involved the technical aspects, including the depth and the number of injection sites. In contrast to the procedure for breast carcinoma, there are only a few variations in potentially useful injection sites.3 Pericervical, intracervical, and peritumoral injections yielded similar SN detection and false-negative rates. Pericervical injections, which were used in our study, appeared to be easy to perform, reproducible, and feasible, even after previous conization.2 The volume of blue dye injected may be a factor influencing SN detection and may explain the variability in reported results.4 In contrast, the use of a combined technique offers a higher detection rate with a low variability.2 Whatever method of detection is used, the SN procedure is not ideal for detecting parametrial SNs. However, parametrial lymph node involvement is low, and the lymph nodes are removed systematically during radical hysterectomy.

Although preliminary results have shown limited validity due to the small sample size, our actual results on 25 consecutive patients confirmed the relevance of the SN procedure; we observed a 95% confidence interval for SN identification and false-negative rates of 80–100% and 0–14%, respectively.

In our protocol, patients underwent only external iliac lymphadenectomy, which explains the relatively small number of lymph nodes removed. After systematic intraoperative examination, the lymphadenectomy was extended to common iliac and paraaortic areas only in patients with positive SNs. Moreover, our mean number of lymph nodes per pelvic side was in line with that of a French multicenter study that used the same protocol.5 This surgical strategy is justified by studies demonstrating the following three facts: 1) lymphatic channels draining laterally to the obturator and external iliac lymph nodes are the most important route for cervical drainage; 2) there is a low incidence of skip metastasis; and 3) overall survival and disease-free survival are similar compared with extensive lymphadenectomy.

The relevance of the SN technique lies in its ability not only to decrease the morbidity of systematic pelvic lymphadenectomy but also to improve the staging of the disease. We agree that reoperating to complete lymphadenectomy in 15% of patients with positive SN diagnosed by IHC and serial sectioning probably leads to a higher morbidity rate compared with primary lymphadenectomy. However, as shown in patients with breast carcinoma,3 frozen section or imprint cytology of SN potentially increases the accuracy of lymph node metastasis diagnosis compared with intraoperative histology based on macroscopic features. Histology with IHC and serial sectioning increase the detection rate of positive lymph node involvement due to better detection of occult metastases, which probably account for disease recurrence. Further studies are required to document the clinical implications of occult metastases.

A laparoscopic approach associated with lymphatic mapping allows a reduction in the aggressiveness of surgical management. The SN procedure, which was introduced as an element of treatment planning, is a promising technique for use in patients with cervical carcinoma.

Emmanuel Barranger M.D.*, Emile Darai M.D. Ph.D.*, * Department of Gynecology and Obstetrics, Hopital Tenon, Paris, France.