Imaging and prostate cancer chemoprevention: Current diagnosis and future directions

Identifying appropriate patients as targets for prostate cancer chemoprevention is a daunting task due to the multiple known and unknown factors contributing to patients' risk profiles. Confirmation of the extent and location of early prostate cancers, as well as prostatic intraepithelial neoplasia (PIN), also requires improved image guidance of biopsy to contain costs. Prostate-specific antigen (PSA) in conjunction with transrectal ultrasound (TRUS) and digital rectal examination (DRE) have been the front-line tests for early prostate cancer. Although advances in MRI continue to improve its accuracy, limited availability and higher costs preclude its widespread use for chemoprevention trials. Improved biopsy risk assessment has been achieved by categorizing TRUS grayscale and vascular findings for each biopsy region. In addition, concomitant suspicious TRUS findings also improved cancer yield per biopsy, as well as the amount and grade of tumor per core. However, TRUS remains operator dependent despite advancements in grayscale and vascular imaging. Additional risk parameters are needed to better localize small disease foci and improve the overall diagnostic performance while containing costs. Future work may improve the specificity of tissue characterization to produce reliable noninvasive biomarkers for monitoring chemoprevention responses of early prostate cancer or PIN.