CYFRA 21-1--clinical applications and analytical requirements.

CYFRA 21-1 has proved to be a useful marker for non-small-cell lung cancer (NSCLC), which is the major form of lung cancer. Its most effective application is in monitoring. CYFRA 21-1 provides diagnostic information about the success of primary surgery, the response to chemotherapy and the detection of relapse. It is also an independent prognostic factor. The diagnostic potential may not be fully used because decision-making is currently based on group reference ranges. It seems useful to carry out systematic studies to investigate if the application can be improved and extended by using individual reference ranges for decision-making. In contrast to most of the other tumour markers the comparability of the commercial CYFRA 21-1- assays currently available on the market is good. The high degree of comparability should be maintained by international standardization. The analytical performance of the currently available commercial CYFRA 21-1 tests meets requirements derived from its current clinical applications. However, there are no data available about the analytical performance under field conditions. CYFRA 21-1, an established tumour marker for lung cancer, should be included in external quality assurance schemes.