Lymphatic mapping and sentinel node biopsy using 99mTc tin colloid in gastric cancer

Abstract

Objective: The aim of this study was to determine the feasibility of sentinel lymph node (SLN) biopsy in patients with gastric cancer for the assessment of regional lymph node status.

Summary background data: SLN is the first draining node from the primary lesion, and it is the first site of lymph node metastasis in malignancy. SLN mapping and biopsy are of great significance in the determination of the extent of lymphadenectomy, allowing patients with gastric cancer to have a better quality of life without jeopardizing survival.

Methods: The SLN biopsy was performed in 46 consecutive patients having gastric cancer with a preoperative imaging stage of T1/T2, N0, or M0. Three hours prior to each operation, Tc tin colloid (2.0 mL, 1.0 mCi) was endoscopically injected into the gastric submucosa around the primary tumor. Subsequently, serial lymphoscintigraphy was performed using a dual-head gamma camera. After the SLN biopsy had been performed using a gamma probe, all patients underwent radical gastrectomy (D2 or D2+alpha). The SLN was cut and immediately frozen-sectioned. A paraffin block was then produced for permanent hematoxylin-eosin staining and immunohistochemistry (IHC).

Results: SLNs were successfully identified in 43 of 46 patients (success rate, 93.5%). On average, 2 (range, 1-8) SLNs were identified per patient. The positive predictive value, negative predictive value, sensitivity, and specificity of SLN biopsy were 100% (11 of 11), 93.8% (30 of 32), 84.6% (11 of 13), and 100% (30 of 30), respectively. SLNs were located at the level I lymph nodes in 38 (88.4%), the level I+II nodes in 2 (4.7%), and the level II nodes in 3 (7.0%). No micrometastases of SLNs was found on IHC for cytokeratin.

Conclusions: SLN biopsy using a radioisotope in patients with gastric cancer is a technically feasible and accurate technique, and it is a minimally invasive approach in the assessment of patient nodal status.

FIGURE 1. Results of SLN biopsy in 46 patients with gastric cancer. The detection rate was 93.5% (43 of 46), and the false negative rate 6.3% (2 of 32). In 6 patients, SLN was the only site of lymph node metastasis.

FIGURE 2. (A) Intraoperative findings of SLNs biopsy in a patient with gastric cancer: The SLN is shown along the left gastric artery (LN #7). (B) The ex vivo sentinel lymph node is placed on the tip of the gamma probe.

FIGURE 3. Distribution of the locations of SLNs in 43 patients with gastric cancer. Most SLNs were located at the perigastric lymph nodes (level I). SLNs were located along the left gastric artery (level II) in 3 patients (7.0%, 3 of 43); in another 2 patients (4.7%, 2 of 43), SLNs were located at levels II and I.