Is SP-1 a marker for testicular cancer?

We measured the serum levels of the pregnancy-associated protein SP-1 by radioimmunoassay in 91 patients with a diagnosis of germ cell testicular cancer. Sixty-seven of the men had active disease, and of these, 52 per cent had elevated levels of SP-1. In contrast, all 24 patients with inactive disease had normal levels. Elevations of SP-1 were associated more often with elevated levels of human chorionic gonadotropin than with elevated levels of alpha-fetoprotein, but elevated SP-1 levels also occurred in patients with normal levels of both of these established tumor markers. We studied serial samples from 21 patients, and in 5 the SP-1 level provided clinically valuable information not provided by the other two markers. SP-1 is a clinically useful marker in germ cell testicular cancer. Further studies are needed to determine the role of the two forms of protein, alpha and beta, and to define the conditions under which the SP-1 level is elevated.