Tissue polypeptide-specific antigen (TPS) determinations before and during intermittent maximal androgen blockade in patients with metastatic prostatic carcinoma

Objective: To evaluate the prognostic significance of serially measured tissue polypeptide-specific antigen (TPS) levels in patients with metastatic prostatic carcinoma treated with intermittent maximal androgen blockade (MAB). To determine its value with respect to predicting response to treatment and time to clinical progression. Finally to compare TPS with prostate-specific antigen (PSA) measurements in terms of prognostic impact in patients with metastatic prostatic carcinoma. Methods and Patients: TPS and PSA measurements were performed before start of and monthly during intermittent MAB in 68 patients participating in EORTC protocol 30954. Both TPS and PSA were measured in serum. Fifty-six patients from eight centers were included in the final analysis because at least three TPS values were available. TPS and PSA values were correlated with clinical course of the disease. Median follow-up was 21.3 months. Three patient groups were defined on clinical grounds: (a) clinically progressive disease (n = 18); (b) clinically stable disease (n = 33); and (c) patients who did not reach a predefined nadir PSA value following 9 months of treatment (n = 5). Results: Pretreatment TPS was significantly higher in the clinically progressive patients than in the other patient groups (p = 0.0041). When grouping patients according to their pretreatment TPS values (cut-off value of 100 U/l) the pretreatment TPS value (>100 U/l) proved to be a statistically significant prognostic factor with respect to time to progression: elevated TPS was associated with a 3.8 increased risk for progressive disease (p = 0.0055). Pretreatment PSA (>100 ng/ml) was of no prognostic value for time to progression. In five patients increase of TPS coincided with or preceded clinical progression during treatment, whereas PSA remained normal. Conclusion: Additional value of pretreatment TPS measurements in metastatic prostate cancer patients is found in defining the patients with rapid clinical progression. Following MAB an increase in TPS signifies clinical progression even if PSA is found to remain normal. (C) 2002 Elsevier Science B.V. All rights reserved.