Background: Although the antiproliferative activity of interferon gamma has been reported in various tumours, this has not been studied in bladder cancer. Proliferative cell nuclear antigen and Ki67 growth fractions were estimated in this study in superficial bladder cancer, as a measure of the antiproliferative effect of interferon gamma.
Materials and methods: Superficial bladder cancer samples before and after four weekly intravesical instillations of 0.7 mg IFN gamma were studied immunohistochemically for proliferative cell nuclear (PCNA) and Ki67 antigens in 25 evaluable patients.
Results: Ki67 growth fraction decreased from median 5% preoperatively to 1% postoperatively (p = 0.0015) and proliferating cell nuclear antigen from 20% to 5% respectively (p = 0.0001). Net reductions of both indices after the interferon instillations were significantly higher in T1 than in Ta tumours (p = 0.0431 for Ki67, and p = 0.0350 for PCNA).
Conclusions: The intravesical instillations of the present dose of interferon gamma have a significant cytostatic effect on superficial bladder cancer cells as this is evidenced by the significant decrease of the growth fractions measured by means of the proliferating cell nuclear and the Ki67 antigens.