抄録
Background and Objectives : Lymph node metastasis is known as a significant predictor of prognosis in colorectal cancer patients. Recently, reverse transcriptase-polymerase chain reaction (RT-PCR) has been applied to detecting micrometastasis. To assess the risk of recurrence and cumulative disease-free survival (DFS), we examined lymph node micrometastasis in a series of colorectal cancer patients.
Methods : A total of 919 lymph nodes obtained from 65 colorectal cancer patients in the past 5 years starting from 1996 were examined using cDNA primers specific for carcinoembryonic antigen (CEA) and cytokeratin 20 (CK20), and were detected tumor cells by the RT-PCR analysis. Subsequently, the cumulative DFS rates were compared between histopathological (pN) and genetic (gN) metastases in the regional lymph node according to UICC TNM classification.
Results : (1) Ninety-five out of 512 histopathologically tumor-free lymph nodes, pN (-) showed positive expression for CEA and CK-20 (gN (+), 18.6%), and 23 out of 39 pN (-) patients showed positive mRNA expression. (2) All the patients showing gN (-) out of pN (-) could survive without any signs of recurrence (3) DFS showed a positive correlation with the increase in pN and gN stages. (4) Even in the pN (-) group, the gN2 patients showed poor prognosis compared with the gN1 or gN0 patients. (5) Among the combinations of pN and gN groups, the DSF rate was significantly higher in groups in the order gN (-) pN (-), gN (+) pN (-), gN (+) pN1 and gN2pN2 (p=0.0010).
Conclusions : Even in histopathologically negative lymph nodes, there is a considerable possibility of micrometastasis. Molecular detection of both CEA and CK-20 mRNAs in regional lymph nodes may introduce better prognostic values for patients with colorectal carcinoma. Patients showing gN (+) and pN1 might require some kind of postoperative adjuvant therapy.
