Contrast Enhanced Transrectal Ultrasonography (TRUS) to Assess Prostatic Vascularity After Radiotherapy (XRT)

Solid tumors, including prostate cancer, commonly exhibit tumor-associated neovascularity (growth of new blood vessels to feed the tumor) with increased microvessel density. Systemic, hormonal, and radiotherapy treatments typically decrease or suppress tumor - associated vascularity through several mechanisms, including apoptosis (process of cell death) and anti-angiogenic pathways (ways to destroy new blood vessel growth). Previously at the investigators' center, they have demonstrated that increased prostatic vascularity (blood vessels defined to prostate) detected ultrasonographically correlated with disease free survival after radical prostatectomy (surgical removal of entire prostate), and may be indicative of higher grade, higher stage disease. The significance of prostate neovascularity in response to treatment with external beam radiotherapy (EBRT) (standard of care) has not been well studied. The investigators hypothesize that prostate cancer that recurs after radiotherapy may exhibit measurable patterns of tumor-associated vascularity, which may represent a minimally invasive marker of cancer stage, grade and response to treatment. The investigators propose a pilot study to assess the feasibility of serial enhanced transrectal ultrasonography (TRUS) examinations during and after radiotherapy for prostate cancer.