Molecular detection of low-level disease in patients with cancer

The accurate detection of low-level disease in patients with cancer is esse ntial to improve the staging of disease and consequently to define appropri ate treatment strategies. Most methods currently used for staging are based on imaging studies and histological and immunocytochemical analysis of tis sues such as bone marrow aspirates, or antibody assays for marker proteins secreted into the circulation. These methods have limited sensitivity. Howe ver, assays for nucleic acid-based markers mag. be valuable tools for the s ensitive detection, assessment, and monitoring of disease status in asympto matic cancer patients. Application of these methods may allow the early det ection of cancer, when the tumour burden is smaller and the disease potenti ally more curable. The last decade has seen the application of polymerase c hain reaction (PCR)-based methods to the detection of tumour in a nide vari ety of compartments, including peripheral blood, bone marrow, lymph nodes, urine, sputum, faeces, pancreatic juice, and more recently plasma. Molecula r detection of disease bg PCR has targeted DNA and RNA markers, including m utations, microsatellites, and tissue-specific gene expression. It is likel y that these molecular methods will provide important clinical information, though their current clinical utility remains unclear. The current status of nucleic acid-based assays for the detection and assessment of disease st atus in the management of patients with solid tumours is reviewed. Copyrigh t (C) 2000 John Wiley & Sons, Ltd.