Detection of disseminated colorectal cancer cells in lymph nodes, blood and bone marrow

Tumor progression after curative resection of colorectal cancer is caused b y tumor cell dissemination, currently undetected by standard clinical stagi ng techniques. The detection of disseminated tumor cells could help to iden tify a patient subgroup at risk for disease relapse who could benefit from adjuvant therapy. In addition, the significance of lymphogenic compared wit h hematogenic colorectal cancer cell dissemination is unknown. However, thi s knowledge would strongly influence the development of future therapeutic regimes. The purpose of this study was to determine the extent of colorecta l cancer cell dissemination in lymph nodes compared with blood and bone mar row. Using a CK 20-reverse transcription (RT)-PCR assay, we examined 279 ly mph nodes, blood, and bone marrow samples from 20 patients with colorectal cancer. Of 16 patients (11 patients stage I, 5 patients stage II) with hist opathologically tumor-free lymph nodes: 14 patients (10 patients stage I, 4 patients stage II) were found to have tumor cells in paracolonic lymph nod es; 12 patients (8 patients stage I, 4 patients stage II) were found to hav e tumor cells in the lymph nodes along the mesentery vessels; and, remarkab ly, 6 patients (4 patients stage I, 2 patients stage II) were found to have tumor cells in the apical lymph nodes. In contrast, tumor cells were detec ted in only two blood and three bone marrow samples of these patients. Thus , lymphogenic tumor cell dissemination is a very common and early event in colorectal cancer, preceding hematogenic tumor cell dissemination. In addit ion, our data strongly suggest that the detection of tumor cells in the api cal lymph node by CK 20-RT-PCR has prognostic relevance. Our results underl ine the therapeutic importance of meticulous lymph node dissection and demo nstrate that the detection of lymphogenic or hematogenic tumor cell dissemi nation by CK 20-RT-PCR will significantly improve current tumor staging pro tocols.