[Lymphatic mapping and sentinel lymph node biopsy in gastric cancer]

Lymphatic mapping and the sentinel lymph node (SLN) concept has been validated in malignant melanoma and breast cancer.However, the application for other solid tumors is still controversial. One of the most promising approaches is selective lymph node staging in gastric cancer.The presented pilot study evaluated the feasibility of the radiocolloid technique in gastric cancer patients and its value in predicting a positive nodal status.

Fifteen patients with gastric cancer (u T(1-3)) underwent endoscopic submucosal injection of 0.4 ml 60 MBq (99m)Tc-Nanocis around the tumor 17 (+/-3) h prior to surgery. After laparotomy the activity of all 16 (JGCA) lymph node stations was measured by a handheld probe. All patients underwent standard gastrectomy with systematic D2 lymphadenectomy. After resection the site was scanned for residual activity. All sentinel lymph nodes (SLN's) were removed ex vivo from the resected specimen and processed for intensified histopathologic assessment including serial sections and immunohistochemistry.

In 14 of 15 patients at least one or more SLN's were obtained (93%), the median number of SLN's was 3 (1-5). Of the 14 patients, 9 revealed lymph node metastases. In eight of the nine patients the sentinel node(s) correctly predicted metastatic lymph node invasion. In five cases the lymph node station with positive sentinel node(s) was the only positive node station resulting in a sensitivity of 8/9 (89%). In one case immunohistochemical staining revealed micrometastases leading to an upstaging in 1/6 of the initially nodal-negative patients.

Lymphatic mapping and sentinel node biopsy using the radiocolloid technique is feasible in gastric cancer. Limited results indicate a correct prediction of the nodal status and the potential of upstaging.Further studies seem to be justified to evaluate the clinical impact of the method.