Interstitial biodegradable balloon for reduced rectal dose during prostate radiotherapy: results of a virtual planning investigation based on the pre- and post-implant imaging data of an international multicenter study.

PURPOSE: To evaluate dose reduction caused by the implantation of an interstitial inflatable and biodegradable balloon device aiming to achieve lower rectal doses with virtual 3D conformal external beam radiation treatment. MATERIALS AND METHODS: An inflatable balloon device was placed, interstitially and under transrectal ultrasound guidance, into the rectal-prostate interspace prior treatment initiation of 26 patients with localized prostate cancer, who elected to be treated with radiotherapy (3D CRT or IMRT). The pre- and post-implant CT imaging data of twenty two patients were collected (44 images) for the purpose of the 3D conformal virtual planning presented herein. RESULTS: The dorsal prostate-ventral rectal wall separation resulted in an average reduction of the rectal V70% by 55.3% (± 16.8%), V80% by 64.0% (± 17.7%), V90% by 72.0% (± 17.1%), and V100% by 82.3% (± 24.1%). In parallel, rectal D2 ml and D0.1 ml were reduced by 15.8% (± 11.4%) and 3.9% (± 6.4%), respectively. CONCLUSIONS: Insertion of the biodegradable balloon into the prostate-rectum interspace is similar to other published invasive procedures. In this virtual dose distribution analysis, the balloon insertion resulted in a remarkable reduction of rectal volume exposed to high radiation doses. This effect has the potential to keep the rectal dose lower especially when higher than usual prostate dose escalation protocols or hypo-fractionated regimes are used. Further prospective clinical investigations on larger cohorts and more conformal radiation techniques will be necessary to define the clinical advantage of the biodegradable interstitial tissue separation device.

PCA3 molecular urine test as a predictor of repeat prostate biopsy outcome in men with previous negative biopsies: a prospective multicenter clinical study.

PURPOSE: We evaluated the clinical usefulness of the PROGENSA® PCA3 Assay for predicting repeat prostate biopsy outcome. MATERIALS AND METHODS: Men with at least 1 prior negative prostate biopsy who were scheduled for repeat prostate biopsy based on best clinical judgment were enrolled at 14 centers. Whole blood and post-digital rectal examination urine samples were collected before extended template transrectal biopsy with 12 or more cores. Urinary PCA3 scores and biopsy outcomes were assessed by logistic regression analysis, which also included age, race, serum prostate specific antigen, clinical stage, family history of prostate cancer and the number of previous negative biopsy sessions. RESULTS: A total of 466 men were included in study and prostate cancer was identified in 21.9%. A PCA3 score cutoff of 25 yielded 77.5% sensitivity, 57.1% specificity, and negative and positive predictive values of 90% and 33.6%, respectively. On multivariable logistic regression men with a PCA3 score of less than 25 were 4.56 times as likely to have a negative repeat biopsy as men with a score of 25 or greater. PCA3 score significantly increased the predictive accuracy of the logistic regression model. At 90% sensitivity adding the PCA3 score to the model increased specificity, and positive and negative predictive values by 22.6%, 6.4% and 7.1%, respectively, relative to the model without the PCA3 score. CONCLUSIONS: The PCA3 score supplements serum prostate specific antigen and other clinical information to provide more accurate prediction of repeat biopsy outcome. Thus, it provides clinicians and patients with independent, clinically useful information to make more informed repeat biopsy decisions.