Image-Guided Sentinel Lymph Node Navigation in Colon Cancer: a Pilot Study
Julio M. Mayol*1,3, Rocio Anula1,3, Roberto Delgado-Bolton2,3, Iris Sanchez-Egido1, Jose Luis Carreras-Delgado2,3, Jesus a. Fernandez-Represa1,3
1Servicio de Cirugia I, Hospital Clinico San Carlos, Madrid, Spain; 2Servicio de Medicina Nuclear, Hospital Clinico San Carlos, Madrid, Spain; 3Unidad de Cirugia Guiada por Imagen, Hospital Clinico San Carlos, Madrid, Spain
Introduction: Over the last two decades, the concept of sentinel lymph node (SLN) biopssy has emerged as a minimally invasive staging tool for melanoma and breast cancer. There is no consensus on its indication for colon cancer because technical issues limit its validity for staging and prognosis. We present our initial experience with intraoperative lymphascintigraphic scanning/mapping for SLN navigation using a portable gamma camera in patients with non-metastasic colon cancer. Patients and
Methods: Between March and October 2007, patients over 18 years of age with histologically proven colorectal adenocarcinoma and non-metastasic disease, scheduled to undergo curative resection by the same group of surgical oncologists were included in this pilot study. Although the group of surgeons had extensive experience with SLN biopsy in melanoma patients, they had not done any colon cancer SLN biopsies previously. The in vivo technique required open exploration of the abdomen to exclude metastasic disease, after location of the primary tumor, a peritumoral subserosal injection of 4 doses (0.5 mCi in 2 ml each) of 99mTc- nanocolloid (diameter < 80 nm) was performed. The intraoperative portable miniature gamma camera (Sentinella 102TM, GEM Imaging SA Valencia, Spain) was intraoperatively used to monitor radiocolloid migration via lymphatic vessels. Once the SLN had been located as a “hot spot” in situ, the specimen was removed as the standard resection, and the node isolated ex vivo for histophatological examination. H&E and immunohistochemical staining were used.
Results: Five women and 4 men with a mean age of 71 years (39-87), all of them had resectable adenocarcinomas without metastasic disease, were included. In three cases the primary tumor was in the right colon, two in the transverse colon and 4 in the left colon. Migration of the radiocolloid to the first lymph node took between 5 and 15 minutes. One SLN was identified and isolated in 8 of 9 patients. The only failure occurred in a patient with a bulky tumor located in the cecum (failure rate: 12%). TNM pathologic staging showed 7 tumours were T3 and 3 were T4. Seven tumours were N0, one were N1 and two N2. In those 3 N-positive patients, the sentinel lymph node was also positive with H&E staining.
Conclusions: Our pilot study suggests that intraoperative image-guided SLN mapping with a portable gammacamera is technically feasible and may be useful for SLN identification in colon cancer patients. Further research will be necessary to determine if image-guided SLN detection and biopsy provides additional prognostic information, improves staging and modifies patient management.