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Oral agent failed to reduce risk of prostate cancer
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Oral toremifene citrate failed to reduce the risk of prostate cancer in men diagnosed with high-grade prostatic intraepithelial neoplasia, according to results of a phase 3 trial.
High-grade prostatic intraepithelial neoplasia (HGPIN) is a potential precursor to prostate cancer. The long-term risk of prostate cancer among men with HGPIN is not well-known, and optimal clinical management strategies remain controversial.
Toremifene (Fareston, ProStrakan) is an oral selective estrogen receptor modulator approved for the treatment of advanced breast cancer. Previous studies showed that toremifene reduced the progression of premalignant HGPIN to prostate cancer, according to background information in the study.
Samir S. Taneja, MD, director of urologic oncology at the New York University Langone Medical Center, and colleagues evaluated the efficacy of toremifene in prostate cancer prevention for men with biopsy-detected isolated HGPIN.
Researchers randomly assigned 1,590 patients to receive 20 mg of toremifene (n=787) or placebo (n=803) for the 3-year, double-blind, multicenter trial.
The median age of enrolled patients was 64 years. Prostate cancer-free survival served as the primary endpoint.
Taneja and colleagues detected cancer in 34.7% of men assigned to placebo compared with 32.2% of men assigned to toremifene, and researchers observed no difference in prostate cancer-free survival (P=.39).
Estimated 3-year prostate cancer-free survival was 54.9% (99% CI, 43.3%-66.5%) in the placebo group vs. 59.5% (99% CI, 48.1%-70.9%) in the treatment group, a difference that was not statistically significant.
Among patients in the placebo arm, 17.9% were diagnosed with prostate cancer within 1 year, 12.9% were diagnosed in the second year and 13.2% were diagnosed in the third year.
“This is distinct from screening cohorts in which a serial decline in cancer detection rate is typically noted on sequential sampling of men with elevated prostate-specific antigen and benign biopsy,” Taneja and colleagues wrote.
Although toremifene demonstrated no effect on the likelihood of prostate cancer diagnosis in men with isolated HGPIN on baseline biopsy, patients with isolated HGPIN seem to represent an ideal group for consideration of prevention strategies, Taneja and colleagues wrote.
In an accompanying editorial, Ian M. Thompson Jr., MD, chairman of the department of urology at the University of Texas Health Science Center, and Robin J. Leach, MD, director of research for the department of urology at the University of Texas Health Science Center, noted that the overwhelming majority of cancers detected after a diagnosis of prostatic intraepithelial neoplasia are low-grade.
“This is perhaps the greater concern, given that it is becoming clear that most of these patients who are ultimately found to have low-grade tumors will not die as a result of their disease,” Thompson and Leach wrote. “Instead of [prostatic intraepithelial neoplasia] as a target of prevention therapies, we would strongly encourage development of biomarkers that predict the development of high-grade tumors, the tumors that are most likely to lead to morbidity and mortality.”
Disclosure: Taneja reports receiving research finding from GTx. Additional researchers report consultant or advisory roles with, research and honoraria from, stock ownership in and employment relationships with GTx. Thompson and Leach report no relevant financial disclosures.
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