Background: This study aimed to clarify the clinical significance of lymph node micrometastasis in ampullary carcinoma.
Materials and methods: Pancreaticoduodenectomy with regional lymphadenectomy was performed for 50 consecutive patients with ampullary carcinoma. A total of 1,283 regional lymph nodes (median, 25 per patient) were examined histologically for metastases. Overt metastasis was defined as metastasis detected during routine histologic examination with hematoxylin and eosin. Micrometastasis was defined as metastasis first detected by immunohistochemistry with an antibody against cytokeratins 7 and 8. The median follow-up period was 119 months after resection.
Results: Overt metastasis was positive in 90 lymph nodes from 27 patients. Micrometastasis was positive in 33 lymph nodes from 12 patients, all of whom also had overt nodal metastases. Patients with nodal micrometastasis had a larger number of lymph nodes with overt metastasis (median, 3.5) than those without (median, 0; P<0.001). Overt metastasis to distant nodes (superior mesenteric nodes, para-aortic nodes) was more frequent (P=0.001 and P=0.038, respectively) in patients with nodal micrometastasis. Nodal micrometastasis was found to be a strong independent prognostic factor on univariate (P<0.0001) and multivariate (relative risk, 5.085; P=0.007) analyses. From among the 27 patients with overt nodal metastasis, the outcome after resection was significantly worse in the patients with nodal micrometastasis (median survival time of 11 months) than in those without (median survival time of 63 months; P=0.0009).
Conclusions: Immunohistochemically detected lymph node micrometastasis indicates intensive lymphatic spread, and thus adversely affects the survival of patients with ampullary carcinoma.