5-S-cysteinyldopa in urine and tumors.

1. The urinary 5-S-CD contents in malignant melanoma subjects (n = 135) and non-melanoma subjects (n = 204) were measured by HPLC. These results suggest that, as a biochemical marker, periodic measurement of urinary 5-S-CD is quite useful for evaluating the determinations of stage classification (UICC, 1987), and the detection of metastases, the therapeutic efficacy of operation or immunochemotherapy against malignant melanoma. 2) Quantitative analyses of 5-S-CD values in tissues from primary malignant melanoma lesions (n = 24) and pigmentary tumors other than melanomas (n = 136) showed 80.6-821.4 ng/mg and N.D.-55.0 ng/mg respectively. In view of the above findings, it was suggested that the pigmentary tumors can be diagnosed as malignant melanoma if the 5-S-CD value in the tissues is higher than 100 ng/mg.