Prognostic relevance of occult tumour cells in lymph nodes in colorectal cancer

Aims Presently, in Europe the treatment of node-negative colorectal cancer (CRC) patients consists of surgical resection of the primary tumour without adjuvant systemic therapy. However, up to 30% of these patients will develop disease recurrence. These high-risk patients are possibly identified by occult tumour cell (OTC) assessment in lymph nodes. In this paper, studies on the clinical relevance of OTC in lymph nodes are reviewed. Methods A literature search was conducted in the National Library of Medicine by using the keywords colonic, rectal, colorectal, neoplasm, adenocarcinoma, cancer, lymph node, polymerase chain reaction, mRNA, immunohistochemistry, micrometastases and isolated tumour cells. Additional articles were identified by cross-referencing from papers retrieved in the initial search. Results The upstaging percentages through OTC assessment and the prognostic relevance of OTC in lymph nodes vary among studies, which is related to differences in techniques used to detect OTC. Conclusions We conclude that OTC examination techniques should be standardized to illuminate whether OTC in lymph nodes can reliably identify high-risk node-negative patients.