Objective: To report the long-term results of the intralesional administration of an immune modifier, interferon-alpha (IFN-alpha) in men with localized prostate cancer, providing a method for drug delivery within the gland under ultrasonographic control.
Patients and methods: Ten men with localized prostate cancer participated in a study involving the intraprostatic injection of IFN-alpha, weekly for 5 weeks. Prostate biopsies were taken and prostate-specific antigen (PSA) levels were measured bi-annually or until the men had an alternative treatment.
Results: The pretreatment mean Gleason score was 7 and the mean PSA level 11 ng/mL. Biopsies after treatment were negative in three patients. Of the remaining seven, six chose to continue watchful waiting. With time, five went on to alternative treatment; one had radical prostatectomy (at 3 months), two had external beam radiotherapy (at 3 and 6 months), and two had androgen suppression (at 3 and 24 months). Of the three men with initial negative biopsies, one died from unrelated causes 13 years later, with an undetectable PSA level; the second remains asymptomatic 13 years later but has an elevated PSA level. The last patient has a low (<4 ng/mL) PSA level, negative biopsies and had 'no cancer' in a resection specimen, 64 months after treatment. These two men remain under active surveillance with no intervention.
Conclusions: After delivery of IFN-alpha directly into the prostate gland, and a long follow-up, it appears that there was some antitumour activity in some patients. The doses used were small and the schedule of administration short. Further evaluation of this, and other agents alone and in combination, might be worthwhile.