Prostate cancer diagnosis among men with isolated high-grade intraepithelial neoplasia enrolled onto a 3-year prospective phase III clinical trial of oral toremifene.

PURPOSE: Prostate cancer (PCa) prevention remains an appealing strategy for the reduction of overtreatment and secondary adverse effects. We evaluated the efficacy of toremifene citrate 20 mg in PCa prevention among men with isolated high-grade prostatic intraepithelial neoplasia (HGPIN) on biopsy. PATIENTS AND METHODS: One thousand five hundred ninety men with HGPIN, or HGPIN and atypia, and no PCa on prostate biopsy were randomly assigned 1:1 to receive toremifene citrate 20 mg or placebo in a 3-year phase III, double-blind, multicenter trial. Men underwent annual biopsy until cancer detection or study end. Efficacy analysis was performed in 1,467 men who underwent at least one on-study biopsy. Baseline risk factors were evaluated to determine influence on cancer detection. RESULTS: Cancer was detected in 34.7% and 32.3% of men in the placebo and treatment groups, respectively, with no observed difference (P = .39, log-rank test) in PCa-free survival. The 3-year Kaplan-Meier PCa-free survival estimate was 54.9% (99% CI, 43.3% to 66.5%) in the placebo group and 59.5% (99% CI, 48.1% to 70.9%) in the treatment group. Exploration of baseline risk factors demonstrated no subset in which a risk reduction was observed. In the placebo group, 17.9%, 12.9%, and 13.6% of men at risk at the beginning of years 1, 2, and 3, respectively, were diagnosed with PCa. CONCLUSION: Although toremifene 20 mg did not lower the PCa detection rate, men with isolated HGPIN have a high likelihood of eventual PCa diagnosis, demonstrating they are ideal candidates for inclusion in chemoprevention trials and require surveillance by periodic prostate biopsy.

Toremifene--a promising therapy for the prevention of prostate cancer and complications of androgen deprivation therapy.

Deregulation of the estrogen axis in humans prompts a series of tissue-specific events. In the breast and prostate, alterations in estrogen signalling lead to genotypic and phenotypic molecular alterations that result in dysplastic cellular appearance, deregulated cell growth and carcinoma. In bone, decreased estrogen leads to increased osteoclastogenesis and bone resorption, decreased bone mineral density and a significant fracture risk. Toremifene is a selective estrogen receptor modulator that exerts pharmacological activity in the breast, bone and prostate. An intense interest in developing this agent for prostate cancer chemoprevention is based on the reduction of premalignant and malignant prostate lesions in a transgenic model of prostate cancer. Biological and clinical activity was demonstrated in Phase II trials by the prevention of progression to prostate cancer in men with high-grade prostate intraepithelial neoplasia and through suppression of bone turnover biomarkers and increased bone mineral density in men on androgen deprivation therapy for prostate cancer.