Tissue polypeptide-specific antigen in renal cell carcinoma.

OBJECTIVES

The usefulness of serum tissue polypeptide-specific antigen (TPS), a cytokeratin 18-associated marker, in renal cell carcinoma (RCC) was assessed in vitro and in vivo.

METHODS

Indirect immunoperoxidase staining for TPS expression was performed on frozen sections of normal renal tissue and RCC specimens. By using a monoclonal TPS immunoradiometric assay, serum TPS concentrations were analyzed in 82 healthy controls, in 20 patients with locoregional RCC before and after surgery and in 18 patients with advanced disease following surgery receiving immunotherapy with interferon-gamma.

RESULTS

Using immunohistochemistry, TPS was found to be expressed by both normal and cancerous renal epithelial cells. The mean TPS concentrations in 82 healthy controls was 56 +/- 49 U/1 with a 95% percentile of 78.5 U/1. Out of 20 patients with locoregional RCC, 8 presented with elevated values (mean 168 +/- 82 U/1) above the cut-off level (78.5 U/1, sensitivity 40%) which dropped to normal within 2 weeks after surgery. During a follow-up period of 1 year, none of the patients presented with tumor recurrence and TPS concentrations remained low (mean 52 +/- 36 U/1). In 18 patients receiving interferon-gamma therapy, serum TPS concentrations were monitored over a period of 12 months. In 5/18 patients, baseline levels were within the normal range (mean 37 +/- 21 U/1); interestingly, these at the same time were the only responders to immunotherapy (n = 2) or at least showed stable disease (n = 3). Response to therapy was reflected by low serum TPS levels (mean 28 +/- 23 U/1) over the entire observation period. Thirteen patients suffered progressive disease during therapy, all of them exhibiting significantly elevated (p < 0.005) pretherapeutic TPS concentrations (mean 186 +/- 124 U/1) that remained equally elevated throughout therapy (mean 192 +/- 102 U/1), reflecting tumor progression.

CONCLUSIONS

TPS might have some clinical value as prognostic marker in RCC, possibly by reflecting the proliferative tendency of the tumor.