There is no question that elevated levels of PSA can serve as an indicator of poor prognosis, and a warning of advancing or recurrent disease. However, a number of recent studies have extended use patterns to make the marker a surrogate measure of response by the tumor to therapy. The authors who studied hormone-refractory disease found that although any reduction in PSA may be associated with improved survival, PSA was not in itself a reliable measure of the degree of response to suramin therapy.
Further evaluation is indicated.