SELECT:: THE NEXT PROSTATE CANCER PREVENTION TRIAL

Can we prevent prostate cancer? Rationale and current status of prostate cancer chemoprevention

Prostate cancer has been one of the most frequent cancers among men in Western countries for the past decade. Investigation of prostate cancer prevention is very attractive, because prostate cancer has a high incidence, long-term natural history, regional difference in incidence, and is effected by sex steroids. Chemoprevention is defined as the use of specific agents to suppress or reverse carcinogenesis and to prevent the development of cancer. The development of chemoprevention strategies against prostate cancer would be of medical and economic importance. Basic and clinical research of chemoprevention of prostate cancer are under active investigation. This article aims to summarize and review the basic evidence and clinical trials on prostate cancer chemoprevention. Recent research has demonstrated that many agents, such as agents altering sex steroid signaling, drugs inducing antiproliferation/differentiation, retinoids, anti-inflammatory drugs, and antioxidants, could be potential preventatives for prostate cancer. Large-scale clinical trials have suggested that 5alpha-reductase inhibitor finasteride, selenium, and vitamin E can function as a chemopreventive agent. Although no definitely effective strategies of prostate cancer prevention have been identified yet, increasing evidence will provide effective and safe strategies that bring clinical benefits.

Localized prostate cancer

Much controversy still surrounds the diagnosis and treatment of localized prostate cancer. Urologists generally believe that early detection and aggressive surgical therapy saves lives despite the absence of confirmatory randomized trials. Furthermore, a recent survey of radiation oncologists and urologists revealed marked polarization toward their own specialties when asked how they would counsel patients on therapy for newly diagnosed localized disease. Some issues are not controversial, however. There is general agreement that pretreatment tumor characteristics, including serum prostate-specific antigen level at diagnosis, tumor grade, and clinical stage as judged by digital rectal examination, are important prognosticators for treatment outcomes independent of the type of treatment. Also, there is sufficient experience with standard therapies (radical prostatectomy and external beam radiotherapy) to counsel patients on the chance for cure and the expected incidence of acute and chronic toxicities. A comparative evaluation of various therapies for prostate cancer should include consideration of cancer control, acute toxicity, treatment-related quality of life issues, salvage of treatment failures, and cost. Within this context, we believe that newly diagnosed patients should be counseled on all available treatment options before embarking on a course of therapy.