Urine excretion of 5-S-cysteinyldopa and serum sialic acid as tumor markers in human melanomas.

This study examines 5-S-cysteinyldopa, which is a melanoma-associated marker, and sialic acid whose increase appears to be a common feature of numerous cancers. In spite of some interferences due to sun exposure, 5-S-cysteinyldopa seems a significant indicator of metastases; the difference between 46 metastasis-negative and 34 metastasis-positive melanomas is significant at P less than 0.001.