Tumor markers in the laboratory: closing the guideline-practice gap

Increasing interest in the use of tumor markers in the clinical management of cancer patients has encouraged development of guidelines by local, national and international groups. Such guidelines generally include recommendations about which markers are likely to be most helpful in given circumstances. Particular requirements and pitfalls in the preanalytical, analytical and postanalytical phases are highlighted. Establishing whether such guidelines are followed in routine practice is difficult, but some indication can be obtained through carefully designed local and national audit projects. Surveys through external quality assessment (proficiency testing) schemes provide a unique means of assessing practice and confirming trends. Such surveys suggest that although increasing numbers of laboratories in the United Kingdom now measure tumor markers, the quality of the service provided over the last ten years has been maintained or improved. While much has already been accomplished, further narrowing of the gap between theory and practice remains a challenge.