Detection and clinical significance of occult tumour cells in colorectal cancer.
BACKGROUND
A variety of techniques have been employed for the detection of occult tumour cells in the blood, bone marrow and lymph nodes of patients with colorectal cancer. This review examines the methods used, results obtained and the clinical significance of studies in this field.


METHODS
A Medline literature search was performed using the terms colorectal cancer, minimal residual disease, micrometastasis, polymerase chain reaction, reverse transcriptase polymerase chain reaction and immunocytochemistry; further references were obtained from key articles.


RESULTS
Immunocytochemical examination of bone marrow is the benchmark for detecting clinically significant occult disease. Larger standardized studies are required to confirm the prognostic significance of molecular assays for the detection of tumour cells in blood and bone marrow. The prognostic significance of lymph node tumour cells detected by either immunohistochemical or molecular methods awaits further affirmation.


CONCLUSIONS
Standardization of terminology and techniques used, combined with large prospective clinical studies, is required if detection of occult residual disease is to become a prognostic marker for recurrence in colorectal cancer.
Tsavellas
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Department of Surgery, Imperial College School of Medicine, Chelsea and Westminster Hospital, 369 Fulham Road, London SW10 9NH, UK.
Patel
H
H
Allen-Mersh
T G
TG
D014408:Biomarkers, Tumor / Q000032:analysis*; D001853:Bone Marrow; D015179:Colorectal Neoplasms / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D008207:Lymphatic Metastasis / Q000473:pathology; D008208:Lymphatic System; D009362:Neoplasm Metastasis / Q000473:pathology; D018365:Neoplasm, Residual / Q000473:pathology; D009360:Neoplastic Cells, Circulating / Q000473:pathology*; D016133:Polymerase Chain Reaction / Q000379:methods; D011379:Prognosis; D021701:Sentinel Lymph Node Biopsy / Q000379:methods
D014408:Biomarkers, Tumor