Local staging of prostate cancer by tumor volume, prostate-specific antigen, and transrectal ultrasound

Acoustic droplet vaporization for temporal and spatial control of tissue occlusion: a kidney study

Acoustic droplet vaporization (ADV) has been introduced with the potential application of tumor treatment via occlusion and subsequent necrosis. New Zealand White rabbits were anesthetized, and their left kidney was externalized. An imaging array and single-element transducer were positioned in a tank with direct access to the kidney's vasculature and renal artery. Filtered droplet emulsions (diameter <6 microm) were injected intra-arterially (IA) into the left heart during insonification of the renal artery, and the extent of blood flow reduction by ADV was compared to the untreated right kidney. Flow cytometry (using colored microspheres) of kidney tissue samples and reference blood from the femoral artery allowed the quantitative estimation of regional blood flow. A maximum regional blood flow reduction in the treated region of >90% and an average organ perfusion reduction of >70% was achieved using ADV. After treatment of the left kidney, the control kidney on the contralateral side showed a maximum decrease in regional blood flow of 18% relative to the pre-ADV baseline. Image-based hyper-echogenicity from ADV of IA injections was monitored for approximately 90 minutes, and cortex perfusion was reduced by >60% of its original value for more than 1 hour. This could be enough time for the onset of cell death and possible tumor treatment via ischemic necrosis. Moreover, currently used radiofrequency tissue ablation-based tumor treatment could benefit from ADV due to the decreased heat loss via vascular cooling.

Role of systematic ultrasound-guided staging biopsies in predicting extraprostatic extension and seminal vesicle invasion in men with prostate cancer

PURPOSE

To assess the presence of extraprostatic extension and seminal vesicle invasion in men with prostate cancer, we performed systematic staging biopsies targeting neurovascular bundles, seminal vesicles, and other extraprostatic tissues before the men underwent radical prostatectomy. We retrospectively evaluated the clinical efficacy of these systematic staging biopsies compared with digital rectal examination (DRE) and transrectal sonography (TRUS).

METHODS

Two hundred forty-four candidates for prostatectomy who had a diagnostic biopsy Gleason score of 8 or higher and/or indications of extraprostatic extension (eg, seminal vesicle invasion) by DRE or TRUS underwent staging biopsies using an 18-gauge Tru-Cut needle under real-time TRUS guidance between June 1997 and March 2000. We determined the number of staging biopsy cores to be taken based on the Gleason score of the diagnostic biopsy as well as abnormal DRE and/or TRUS findings. The chi-square test was used to evaluate the statistical significance of differences.

RESULTS

There were no complications of staging biopsy. In 75 (31%) of the 244 patients, results of the staging biopsies were positive. The clinical stage was upgraded by staging biopsy in 18 (24%) of these 75 patients. After the staging biopsies, 90 patients underwent radical prostatectomy. Among these 90 patients, staging biopsy specimens were positive for cancer in 20 (47%) of the 43 patients who received neoadjuvant therapy and in 1 (2%) of the 47 patients who did not receive neoadjuvant therapy. There were no false-positive staging biopsies in either group. Among the 90 patients who underwent radical prostatectomy, the false-negative rate for the prediction of organ-confined disease was 43% (30/69) for staging biopsies compared with 29% (10/34) for TRUS. The diagnostic accuracy of staging biopsies (67%; 60/90) was higher than that of DRE (52%; 47/90; p < 0.05) but lower than that of TRUS (79%; 71/90; p = 0.066).

CONCLUSIONS

Staging biopsies can reliably sample extraprostatic tissue, including the seminal vesicles and neurovascular bundles. Positive staging biopsy results can aid in the selection of treatment options and in the prediction of outcome for individual patients by providing definitive histologic confirmation of locally advanced disease. Conventional predictive variables for staging can be applied when the results of staging biopsies are negative.

Prediction of organ-confined disease by prostate-specific antigen nadir after neoadjuvant therapy

BACKGROUND

It is not clear whether or not serum prostate-specific antigen (PSA) levels after androgen deprivation prior to radical prostatectomy (neoadjuvant therapy) have any value in the prediction of the final pathologic stage.

METHODS

We conducted a study on 49 patients who underwent retropubic radical prostatectomy following neoadjuvant therapy for clinical stage T1c, T2, and T3a prostate cancer. We evaluated progression-free survival based on the PSA failure rate and the predictive value of the PSA nadir after neoadjuvant therapy and other clinical factors to determine the most important predictor of organ confinement.

RESULTS

Of the 49 patients, 30 had organ-confined disease. Of 31 patients without adjuvant therapy after surgery, the PSA failure-free rates at 2 years were 81.6 and 34.3% in the subset of organ-confined disease and non-organ-confined disease, respectively (P= 0.0031). Of the 18 patients with adjuvant androgen deprivation therapy after surgery, the PSA failure-free rate at 2 years was 100% and 59.7% in patients with organ-confined disease and non-organ-confined disease, respectively. Baseline PSA (P=0.037), PSA nadir (P<0.0001) and PSA density (P=0.003) significantly correlated with organ confinement. Multivariate logistic regression analysis revealed that the PSA nadir was the only independent predictor of organ confinement (P = 0.044).

CONCLUSIONS

There was a trend that the patients with non organ-confined disease had a higher probability of PSA failure than did the patients with organ-confined disease. The PSA nadir after neoadjuvant therapy was the strongest predictor of organ confinement. The predictive value of the serum PSA nadir should be validated in well-designed larger population-based studies.

Evaluation of a decision-support system for preoperative staging of prostate cancer

The usefulness and effectiveness of a decision-support system for preoperative staging of prostate cancers (PCES) were evaluated. The study population consisted of 43 consecutive patients with the preoperative diagnosis of prostate cancer who underwent surgical operation. Results obtained using the PCES were compared with staging by four urology attending physicians and five urology residents. The effect of PCES consultation on the physicians' staging of prostate cancer was also evaluated. To confirm the usefulness of the clinical findings of prostate-specific antigen, prostate-specific antigen density, prostate volume, and abnormal Gleason score in the PCES, their receiver operating characteristic (ROC) curves for diagnosis of advanced prostate cancer were plotted. The values of the areas under the curves were 0.772, 0.800, 0.531, and 0.752. The stage of prostate cancer was correctly determined by the PCES for 38 of the 43 patients, yielding 88.4% preoperative diagnostic accuracy. The PCES was significantly more accurate than two of the attending physicians and all residents. PCES consultation improved the residents' staging accuracy to approximately that of the attending physicians. The effect of PCES consultation on the residents' staging was significantly (p < 0.001) greater than the effect on the physicians' staging. The PCES may be useful in the preoperative staging of prostate cancers, especially during residency. The system's accuracy in determining the stage of advanced prostate cancer may make it possible to avoid unneccesary surgical operations.

Systematic sextant biopsies in the prediction of extracapsular extension at radical prostatectomy

OBJECTIVES

To evaluate the clinical utility of transrectal ultrasound-guided systematic sextant needle biopsies in the prediction of extracapsular extension (ECE) at radical prostatectomy.

METHODS

A retrospective analysis of 104 men who underwent systematic biopsy and radical prostatectomy at our institution was performed. All patients underwent preoperative staging by transrectal ultrasound and transrectal ultrasound-guided systematic sextant biopsy. The presence of pathologic ECE was correlated to the number of positive core biopsies on each side of the prostate by chi-square analysis. Sensitivity, specificity, positive and negative predictive values, and likelihood ratios (LRs) were calculated for both positive (two or three biopsies positive per side) and negative (no or one positive biopsy per side) test results.

RESULTS

Forty-two (20.2%) of 208 sides demonstrated evidence of ECE at radical prostatectomy. Chi-square analysis demonstrated a significant correlation between the number of positive biopsies and the presence of ECE at radical prostatectomy (P = 0.001). Overall, the finding of multiple positive core biopsies (two or three per side) had predictive value with regard to the presence of ECE (sensitivity 62%, specificity 77%, positive predictive value 40%, negative predictive value 89%). The corresponding LRs were 2.5 for a positive and 0.5 for a negative test result.

CONCLUSIONS

The probability of ECE at radical prostatectomy can be more accurately assessed preoperatively by the combined use of transrectal ultrasound and systematic sextant needle biopsies.

Construction and application of hierarchical decision tree for classification of ultrasonographic prostate images

A non-parametric algorithm is described for the construction of a binary decision tree classifier. This tree is used to correlate textural features, computed from ultrasonographic prostate images, with the histopathology of the imaged tissue. The algorithm consists of two parts; growing and pruning. In the growing phase an optimal tree is grown, based on the concept of mutual information. After growing, the tree is pruned by an alternating interaction of two data sets. Moreover, the structure and performance of the constructed tree are compared to the results using a slightly modified corresponding growing and pruning algorithm. The modified algorithm provides better retrospective and prospective classification results than the original algorithm. The use of the tree for automated cancer detection in ultrasonographic prostate images results in retrospective and prospective accuracy of 77.9% and 72.3%, respectively. Using this tissue characterisation, a supporting tool is provided for the interpretation of transrectal ultrasonographic images.