Abstracts
2001 Digestive Disease Week

# 2461 Genetic Lymph Node Staging for Pancreatic Cancer
Shoji Nakamori, Terumasa Yamada, Ken Shiozaki, Jiro Okami, Nobuyasu Hayashi, Masanori Tsujie, Hiroaki Nagano, Keizo Dono, Koji Umeshita, Masato Sakon, Morito Monden, Suita, Japan

BACKGROUND: The value of surgical treatment for patients who are thought to have potentially resectable pancreatic cancer still remains to be questioned. Even in the patients who underwent pathologically curative resection, we often encounter local recurrences or distant metastasis soon after surgery. This uncertainty could be due to the routine pathological staging that often fails to detect micro-metastasis and results in falsely optimistic tumor staging. Reliable and sensitive method for the more accurate evaluation of the extent of local and distant spread of pancreatic cancer could improve prognosis and hence provide a better planning and optimal management strategies. The presence or absence of tumor cells in the regional lymph nodes is one of the most important prognostic factors in pancreatic cancer. To improve the accuracy of lymph node staging, we prospectively assessed clinical value of genetic staging of lymph node metastases using K-ras gene mutations as a molecular marker in patients with pancreatic cancer who underwent curative surgery.

METHODS: We examined the presence of K-ras gene mutations in lymph nodes from 25 tumors by mutant-allele-specific-amplification method.

RESULTS: Mutated K-ras genes were found in lymph nodes of 13 patients. Seven of these patients had no evidence of pathological nodal involvement. Overall survival of the patients without nodes containing mutated K-ras gene were significantly better than that of the patients with them (p< 0.001). Furthermore, overall survival of six patients with genetically metastasis-positive nodes limited to peripancreatic area was significantly better than that of seven patients with genetical metastasis in lymph nodes beyond the peripancreatic areas (p=0.018).

CONCLUSIONS: These findings suggest that detection of K-ras mutations in lymph nodes may be clinically useful to assess accurate lymph node staging and to stratify the patient with pancreatic cancer who are at high or low risk for recurrence after curative surgery.