Faculty Bibliography

Testosterone remains a key target in the treatment of advanced prostate cancer. The relationship of free testosterone to prostate cancer treatment and outcomes remains largely unexplored. A consensus of prostate cancer experts was convened in 2013 to review current knowledge surrounding relationship of total and free testosterone to prostate cancer, discuss the free hormone hypothesis, and highlight future avenues for therapeutics. Free testosterone may better reflect prostate cancer tissue androgen levels than serum total testosterone concentration. Free testosterone deserves more research regarding its relation to clinical outcomes.

PURPOSE: Optimization of prostate biopsy requires addressing the shortcomings of standard systematic transrectal ultrasound guided biopsy including false negative rates, incorrect risk stratification, detection of clinically insignificant disease, and the need for repetitive biopsy. MRI is an evolving noninvasive imaging modality that increases the accurate localization of prostate cancer (PCa) at the time of biopsy, thereby enhancing clinical risk assessment, and improving the ability to appropriately counsel patients regarding therapy. The purpose of this review is to 1) summarize the various sequences that comprise a prostate multiparametric MRI exam along with its performance characteristics in cancer detection, localization and reporting standards, 2) evaluate potential applications of MRI targeting in prostate biopsy among men with no previous biopsy, a negative previous biopsy, and those with low stage cancer and 3) describe the techniques of MRI-targeted biopsy and their comparative study outcomes MATERIALS AND METHODS: A bibliographic search covering the period up to October, 2013 was conducted using MEDLINE(R)/PubMed(R). Articles were reviewed and categorized based on which of the three objectives of this review was addressed. Data was extracted, analyzed, and summarized. RESULTS: Mp-MRI consists of anatomic T2-weighted imaging coupled with at least 2 functional imaging techniques and has demonstrated improved PCa detection sensitivity up to 80% in the peripheral zone and 81% in the transition zone. A PCa MRI suspicion score has been developed and is depicted using the Likert or PI-RADS scale for better standardization of MRI interpretation and reporting. Among men with no previous biopsy, MRI increases the frequency of significant cancer detection to 50% in low risk and 71% in high risk patients. In low risk men, the negative predictive valve of a combination of negative MRI with prostate volume parameters is nearly 98%, suggesting a potential role in avoiding a biopsy and reducing overdetection/overtreatment. Among men with previous negative biopsy, 72-87% of cancers detected by MRI guidance are clinically significant. Among men with known low risk cancer, repeat biopsy by MR-targeting demonstrates a high likelihood of confirming low risk disease in low suspicion score lesions and for upgrading in high suspicion score lesions. Techniques of MRI-targeted biopsy include visual estimation TRUS-guided biopsy, software co-registered MRI-US TRUS-guided biopsy, and in-bore MRI-guided biopsy. Although the improvement in accuracy and efficiency of visual estimation biopsy compared to systematic appears limited, both co-registered MRI-US biopsy and in-bore MRI-guided biopsy appears to increase cancer detection rates in conjunction with increasing suspicion score. CONCLUSIONS: Use of MRI for targeting prostate biopsies has potential to reduce the sampling error associate with conventional biopsy by providing better disease localization and sampling. More accurate risk stratification through improved cancer sampling may impact upon therapeutic decision-making. Optimal clinical application of MRI-targeted biopsy remains under investigation.