Area of nodal metastasis and radioisotope uptake in sentinel nodes of upper gastrointestinal cancer

Sentinel node navigation surgery has been introduced for the treatment of gastrointestinal tumor. As few studies have examined relationships between metastatic area and radioisotope uptake in sentinel nodes, the present study examined this relationship for gastric and esophageal cancers.

Subjects comprised 43 patients (esophageal cancer, n = 19; gastric cancer, n = 24) with < or =3 lymph node metastases in whom sentinel node mapping with radio-guided methods was performed. Radioisotope uptake was measured after surgery for all dissected lymph nodes. Metastatic area was calculated using the following formula: metastatic area (%) = (area of metastasis/total area of lymph node) x 100. Based on radioisotope uptake, lymph nodes were divided into RI(-) and RI(+) groups.

In 35 patients, > or =1 metastatic node was present among the sentinel nodes. In 1 patient, no sentinel nodes were detected. No lymph node metastasis was found in sentinel nodes in the remaining seven patients. Lymph nodes were diagnosed as metastatic using preoperative imaging. Mean (+/-SD) metastatic area was significantly higher for RI(-) (68.3 +/- 20.5%) than for RI(+) (15.1 +/- 20.8%; P < 0.0001). Radioisotope uptake was decreased in lymph nodes with >60% metastatic area.

The fact that radioisotope uptake is not detectable in some lymph nodes with >60% metastatic area must be considered when planning sentinel node navigation surgery.