Analysis of potential markers for detection of submicroscopic lymph node metastases in breast cancer

We have developed sensitive assays for cytokeratin (K) 8, 16, 19, stromelys in 3 (ST3), MUC1 and maspin mRNAs using reverse transcription polymerase ch ain reaction (RT-PCR) and used these to assess lymph node status in patient s undergoing surgery for breast cancer. In addition the RT-PCR assays were tested against lymph nodes from non-cancer patients to determine their spec ificity. Despite high sensitivity RT-PCR assays for K8, K16, K19, ST3 and m aspin were not found to be useful as markers of submicroscopic disease as t ranscripts of these genes were detected in the great majority of control ly mph nodes tested. Expression of MUC1 was also not found to be useful as it was both insensitive and non-specific. The importance of assessing potentia l markers against an adequately sized control population is demonstrated, a s failure to do so can lead to erroneous conclusions.