Future studies in localized prostate cancer. What should we think? What can we do?

The role of cyclooxygenase-2 inhibition for the prevention and treatment of prostate carcinoma

Experimental and epidemiologic studies have demonstrated that nonsteroidal antiinflammatory drugs (NSAIDs) are effective in the prevention of human cancers. Nonsteroidal antiinflammatory drugs inhibit the cyclooxygenase (COX) enzyme that functions to convert arachidonic acid to prostaglandins (PGs). Cyclooxygenase-2, a key COX isoenzyme, is rapidly induced in response to inflammatory stimuli, growth factors, cytokines, and promoters of neoplastic growth. Cyclooxygenase-2-catalyzed reactions may be involved in carcinogenesis via 2 distinct mechanisms: (1). DNA damage and (2). PG-mediated effects. Reactions mediated by COX-2 form reactive oxygen species that can directly induce the oxidation of DNA or instigate the bioactivation of carcinogens. Prostaglandin E2, a byproduct of COX-2-mediated arachidonic acid metabolism, exhibits several biologic actions that have been shown to promote tumorigenesis and tumor progression. These actions include increased cell proliferation, promotion of angiogenesis, and the elevated expression of the antiapoptotic protein Bcl-2. In addition, PGE2 decreases natural killer cell activity and alters immune surveillance. In vitro experimental studies find that COX-2 inhibitors decrease cellular proliferation, increase apoptosis, and modulate genes involved in cell cycle regulation. Evidence from animal studies supports a role for NSAIDs in prostate cancer (CaP) prevention. Population-based studies have observed a reduced incidence of CaP among men using NSAIDs. Because CaP evolves slowly and rarely strikes men before the sixth or seventh decade of life, any strategy to delay or lengthen the time to development of clinically evident CaP, such as chemoprevention strategies, would greatly impact the natural history of this disease. Recent progress and critical analyses in the roles of COX-2 inhibition on prostate carcinogenesis and CaP prevention will be presented.

Improving appropriate selection of radical prostatectomy for prostate cancer

Men 70 and older should usually not have radical prostatectomies to treat prostate cancer. Using Medicare claims data, 10 hospitals were identified that performed 29% of the radical prostatectomies in men 70 and older in Kentucky and Indiana. A quality improvement project was conducted with the purpose of decreasing the performance of radical prostatectomy in men 70 and older. On the advice of an expert committee, the peer review organization and the 10 hospitals collaborated in developing and implementing improvement plans that included institutional review of practices and informed consent policies. The project was associated with significant improvement in the use of radical prostatectomy. In addition, substantial savings in Medicare payments were observed, and improvement in the quality of life for Medicare men was anticipated.

Detection of latent prostate cancer from routine screening: comparison with breast cancer screening

OBJECTIVES

One criticism of routine prostate cancer screening is the possibility that latent prostate cancer would be detected and treated in men who would otherwise never need treatment for their prostate cancer. This increase in latent cancer detection with screening could lead to overtreatment, with its resulting increases in morbidity, mortality, and health care costs. In contrast, breast cancer screening is widely accepted, and there is little concern about latent breast cancer detection and overtreatment of breast cancer due to screening. This study compares the detection of latent prostate cancer from screening with the detection of latent cancer in an established cancer screening program (breast cancer screening) and examines the risk that screening leads to an increase in detection of latent cancer over traditional methods of detection for both breast and prostate cancer.

METHODS

The present study reviews outcomes data from several large prostate and breast cancer screening trials. The natural history of latent prostate and breast cancer is then reviewed. By applying this information, the rate of latent prostate cancer detection and latent breast cancer detection with screening is compared.

RESULTS

Recent large-scale prostate cancer screening studies have reported a latent cancer detection rate of 2.9% to 8.0%. This rate of detection is virtually the same as that found by traditional methods of detection. Ductal carcinoma in situ (DCIS) is a noninvasive breast cancer that accounts for 16.2% to 23.7% of breast cancers detected in screening programs using mammography. The literature estimates that DCIS will remain latent in 50% to 66% of patients. These data suggest that the latent breast cancer detection rate in screening programs is 8.1% to 15.6%, which is a threefold to fivefold increase compared with the detection rate of latent breast cancer prior to screening with mammography.

CONCLUSIONS

These results suggest that the latent prostate cancer detection rate from screening is similar to or less than the latent breast cancer detection rate from screening. Furthermore, prostate cancer screening does not appear to increase the detection rate of latent cancer over traditional methods of detection. This should eliminate concern that prostate cancer screening will lead to overtreatment of prostate cancer.