The role of imaging studies and molecular markers for selecting candidates for radical prostatectomy

Optimal cost-effective staging evaluations in prostate cancer

A new diagnosis of prostate cancer presents to both the patient and physician questions regarding the best approach for further assessing the extent of disease prior to selecting a treatment strategy. In addition to the initial clinical data such as serum prostate-specific antigen level, findings on digital rectal examination, and core biopsy Gleason score, several procedures and imaging modalities are available to further stage newly diagnosed prostate cancer. A substantial percentage of the cost of managing prostate cancer is directly related to staging evaluations. Often, staging evaluations are performed that have limited test performance characteristics, subject the patient to unnecessary morbidity, or simply do not provide additional useful clinical information. It is important that the physician be familiar with the indications for the available staging modalities as well as the test performance characteristics in order to proceed appropriately and in an economically judicious fashion. This paper reviews the literature on this topic and summarizes previous experiences with procedures and imaging modalities for staging newly diagnosed prostate cancer.

[Prostate cancer: Diagnosis and staging]

The discovery and the use of serum prostate specific antigen (PSA) has considerably improved the diagnosis of prostate cancer during the past 20 years. Before PSA era, early diagnosis was only based on the digital rectal examination (DRE) of which the Limitations have been evidenced; over half of the tumours diagnosed by such means had already spread out of the prostate and were incurable. Assessment of serum PSA has allowed the diagnosis to be made at an earlier stage of the disease, curable by current treatments. Whichever the diagnostic tools, transrectal ultrasound (TRUS) prostatic biopsies remain necessary for diagnosis ascertainment, taking into account the low specificity of PSA assessment. The feasibility of a diagnosis at an early and curable stage of the disease has logically resulted in screening procedures aimed at reducing the high mortality related to prostate cancer. The numerous publications on prostate cancer screening provide precise information on the accuracy of available diagnostic means (PSA, DRE, TRUS, combined PSA and DRE), on the characteristics of screened tumours (stage and differentiation), and also on the population of men likely to benefit from the screening (age at beginning and end of the screening, frequency of PSA testing, identification of the men with ethnic and/or genetic predisposition). In those early diagnosed prostate cancers, the assessment of loco-regional cancer extension (extracapsular and/or, microscopic nodal involvement), remains unsatisfactory because no imaging technique (ultrasonography, CT scan, MRI,...) allows visualising the tumour itself or microscopic metastases. Nevertheless, the combination of multiple parameters such as DRE data, PSA level, biopsy data and tumour differentiation helps approaching with an increasing precision (nomograms) the true pathologic stage of the disease. Such advances allow distinguishing, among the very heterogeneous group of prostate cancers, tumours that differ from one to another in terms of disease stage, progression and prognosis, which is helpful for the determination of an adapted therapeutic strategy.

Diagnosis and treatment of prostate cancer

Many controversies surround the management of prostate cancer to include screening practices, diagnosis, and treatment options. The lack of randomized prospective studies comparing the various definitive treatment modalities currently available occasionally can make the decision process challenging for patients and their providers. In this setting of controversy, the cost of treating clinically localized prostate cancer is significant. In the face of these unanswered questions, this article summarizes some important principles regarding the diagnosis and treatment of prostate cancer. This review is limited to the diagnosis and management of clinically localized disease.

Eligibility and outcomes reporting guidelines for clinical trials for patients in the state of a rising prostate-specific antigen: recommendations from the Prostate-Specific Antigen Working Group

PURPOSE

To define methodology to show clinical benefit for patients in the state of a rising prostate-specific antigen (PSA).

RESULTS

HYPOTHESIS

A clinical states framework was used to address the hypothesis that definitive phase III trials could not be conducted in this patient population.

PATIENT POPULATION

The Group focused on men with systemic (nonlocalized) recurrence and a defined risk of developing clinically detectable metastases. Models to define systemic versus local recurrence, and risk of metastatic progression were discussed.

INTERVENTION

Therapies that have shown favorable effects in more advanced clinical states; meaningful biologic surrogates of activity linked with efficacy in other tumor types; and/or effects on a target or pathway known to contribute to prostate cancer progression in this state can be considered for evaluation.

OUTCOMES

An intervention-specific posttherapy PSA-based outcome definition that would justify further testing should be described at the outset. Reporting: Trial reports should include a table showing the number of patients who achieve a specific PSA-based outcome, the number who remain enrolled onto the trial, and the number who came off study at different time points. The term PSA response should be abandoned.

TRIAL DESIGN

The phases of drug development for this state are optimizing dose and schedule, demonstration of a treatment effect, and clinical benefit. To move a drug forward should require a high bar that includes no rise in PSA in a defined proportion of patients for a specified period of time at a minimum. Agents that do not produce this effect can only be tested in combination. The preferred end point of clinical benefit is prostate cancer-specific survival; the time to development of metastatic disease is an alternative.

CONCLUSION

Methodology to show that an intervention alters the natural history of prostate cancer is described. At each stage of development, only agents with sufficient activity should be moved forward.

The percentage of prostate needle biopsy cores with carcinoma from the more involved side of the biopsy as a predictor of prostate specific antigen recurrence after radical prostatectomy

BACKGROUND

The authors previously found that, although the total percentage of prostate needle biopsy cores with carcinoma was a significant predictor of prostate specific antigen (PSA) failure among men undergoing radical prostatectomy (RP), there was a trend toward a lower risk of recurrence in patients with positive bilateral biopsies, suggesting that high-volume, unilateral disease was a worse predictor of outcome than an equivalent number of positive cores distributed over two lobes. In the current study, the authors sought to compare the total percentage of cores with carcinoma directly with the percentage of cores from the more involved or dominant side of the prostate with carcinoma for their ability to predict outcome among men who underwent RP.

METHODS

A retrospective survey of 535 patients from the Shared Equal Access Regional Cancer Hospital database who underwent RP at 4 different equal-access medical centers between 1988 and 2002 was undertaken. The total percentage of cores positive was compared with the percentage of cores positive from the dominant and nondominant sides for their ability to predict biochemical recurrence after RP. The best predictor then was compared with the standard clinical variables PSA, biopsy Gleason score, and clinical stage in terms of ability to predict time to PSA recurrence after RP using multivariate analysis.

RESULTS

The adverse pathologic features of positive surgical margins and extracapsular extension were significantly more likely to be ipsilateral to the dominant side on the prostate biopsy. The percentage of cores positive from the dominant side provided slightly better prediction (concordance index [C] = 0.636) for PSA failure than the total percentage of cores positive (C = 0.596) and markedly better than the percentage of cores from the nondominant side (C = 0.509). Cutoff points for percentage of cores positive from the dominant side were identified (< 34%, 34-67%, and > 67%) that provided significant risk stratification for PSA failure (P < 0.001). On multivariate analysis, the percentage of cores positive from the dominant side was the strongest independent predictor of PSA recurrence (P < 0.001). Biopsy Gleason score (P = 0.017) also was a significant, independent predictor of recurrence. There was a trend, which did not reach statistical significance, toward an association between greater PSA values and biochemical failure (P = 0.052). Combining the PSA level, biopsy Gleason score, and percentage of cores positive from the dominant side of the prostate resulted in a model that provided a high degree of prediction for PSA failure (C = 0.671).

CONCLUSIONS

The percentage of cores positive from the dominant side of the prostate was a slightly better predictor of PSA recurrence than was the total percentage of cores positive. Using the percentage of cores from the dominant side along with the PSA level and the biopsy Gleason score provided significant risk stratification for PSA failure.

Prostate cancer: radical prostatectomy

Today, more men than ever before are being followed after radical prostatectomy. Prognosis and follow-up should be based on the pathologic specimen. Measurable prostate-specific antigen (PSA) after surgery defines failure, with time to detectable PSA and rate of PSA rise being useful prognostic factors. The natural history of untreated biochemical failure is protracted, a fact to be considered in discussions of adjuvant treatment. Early in disease recurrence, imaging studies to locate residual disease rarely are useful clinically. Both adjuvant and salvage radiation to the prostate bed have benefits and risks, but neither is superior in overall prostate cancer survival. The timing of hormone therapy remains largely empiric. The promise of effective cytotoxic chemotherapy still is greater than its actual benefits, although novel cytostatic agents are being developed. The future management of this disease will improve with better molecular definition of risk and therapeutic response.

Predicting biochemical recurrence after radical prostatectomy for patients with organ-confined disease using p27 expression

OBJECTIVES

It is unclear why men who undergo radical prostatectomy (RP) and are found to have pathologically organ-confined disease develop prostate-specific antigen (PSA) recurrences. We previously found that patients with less than 45% of cells in the prostate needle biopsy specimen (PNBx) staining positive for the cell cycle regulator p27 had a significantly increased risk of biochemical recurrence after RP. We sought to determine whether p27 staining in the PNBx specimen might serve as a molecular marker for PSA failure in the subset of patients who develop PSA recurrence despite organ-confined disease at RP.

METHODS

The PNBx specimens of 161 men treated with RP between 1991 and 2000 were examined for p27 expression using immunohistochemistry. The p27 cutpoint of less than 45% expression was used to define the high and low-risk categories. Patients were separated into two groups for analysis: organ-confined (pT2 and negative surgical margins) and non-organ-confined (pT2 with positive surgical margins, pT3, pT4, or lymph node involvement). The mean and median follow-up for patients with organ-confined and non-organ-confined disease was 47 and 43 months and 42 and 38 months, respectively. Multivariate Cox proportional hazards analysis was used to examine the preoperative clinical variables that were the strongest predictors of biochemical recurrence after RP among each group.

RESULTS

Among organ-confined patients, p27 expression was the only significant independent predictor of the time to biochemical recurrence after RP (hazard ratio 5.15, 95% confidence interval 1.41 to 18.83, P = 0.013). Among patients with non-organ-confined disease, the percentage of biopsy tissue with cancer, biopsy Gleason score, and PSA level were independent predictors of PSA recurrence. p27 expression was not a significant independent predictor of PSA recurrence among men with non-organ-confined disease.

CONCLUSIONS

p27 expression in the PNBx was a significant independent predictor of PSA failure for patients with pathologically organ-confined disease, but not for those with non-organ-confined disease. Patients with organ-confined disease but low p27 expression had a greater than fivefold risk of developing PSA recurrence than were men with high p27 expression, suggesting that p27 may be a molecular marker associated with micrometastatic disease at the time of RP.

Practical considerations in radical retropubic prostatectomy

Overall, in the hands of an experienced surgeon, the outcomes following radical prostatectomy are excellent. Attention to patient selection, preoperative management, surgical technique, and postoperative management are essential factors contributing to favorable outcomes for men with a biologically significant cancer and 10-year life expectancy. For these men, radical prostatectomy represents the optimal management based on cure, morbidity, and quality of life.

An artificial neural network for prostate cancer staging when serum prostate specific antigen is 10 ng./ml. or less

PURPOSE

An artificial neural network was developed to improve the prediction of pathological stage before radical prostatectomy based on variables available at biopsy and clinical parameters.

MATERIALS AND METHODS

We used the prospectively accrued European prostate cancer detection data base to train an artificial neural network to predict pathological stage in 200 men with serum prostate specific antigen (PSA) 10 ng./ml. or less who underwent radical prostatectomy. Variables included in the artificial neural network were patient age, serum PSA, free-to-total PSA ratio, PSA velocity, transrectal ultrasound calculated total and transition zone volumes with their associated PSA parameters (transition zone PSA density and PSA density), digital rectal examination and Gleason score on biopsy. Two multilayer perceptron neural networks were trained on the remaining variables. Data on the 200 patients were divided randomly into a training set, a test set and a validation or prospective set.

RESULTS

Overall classification accuracy of the artificial neural network was 92.7% and 84.2% for organ confined and advanced prostate cancer staging, respectively. For preoperatively predicting local versus advanced stage the area under the ROC curve for the artificial neural network was significantly larger (0.91) compared with logistic regression analysis (0.83), Gleason score (0.69), PSA density (0.68), prostate transition zone volume (0.63) and serum PSA (0.62) (all p <0.01).

CONCLUSIONS

The artificial neural network outperformed logistic regression analysis and correctly predicted pathological stage in more than 90% of the validation patients with serum PSA 10 ng./ml. or less based on clinical, biochemical and biopsy data. In the future artificial neural networks may represent a significant step for improved staging of prostate cancer when counseling patients referred for radical prostatectomy or other curative treatments.

Preoperative p27 status is an independent predictor of prostate specific antigen failure following radical prostatectomy

PURPOSE

p27 is an important cell cycle regulator, and decreased expression in radical prostatectomy specimens is associated with an increased risk of prostate specific antigen (PSA) failure. To our knowledge no prior study has shown that preoperative p27 status independently predicts recurrence after radical prostatectomy.

MATERIALS AND METHODS

The prostate needle biopsy specimens of 161 men treated with radical prostatectomy were examined for p27 expression using immunohistochemistry. Various p27 cut points were examined for their ability to separate patients into groups with different risk for time to biochemical recurrence following radical prostatectomy. The best p27 cut point was compared to other clinical variables (PSA, clinical stage, age, biopsy Gleason score and percent of prostate needle biopsy with cancer) on multivariate analysis to determine which variables independently predicted biochemical failure.

RESULTS

A p27 cut point of less than 45% positive staining cells resulted in significant preoperative risk stratification for time to PSA failure (HR 2.41, p = 0.010). On multivariate analysis serum PSA (HR 1.04, p = 0.011), biopsy Gleason score (HR 1.51, p = 0.011), percent of biopsy tissue with cancer (HR 10.01, p = 0.001) and less than 45% p27 positive cells (HR 2.44, p = 0.014) were all independent predictors of biochemical recurrence.

CONCLUSIONS

Preoperative p27 expression is an independent predictor of time to biochemical recurrence following radical prostatectomy. Patients with less than 45% p27 positive cells in the prostate needle biopsy specimen have almost a 2.5-fold increased risk of biochemical recurrence. To our knowledge this study is the first to show that p27 status of the prostate needle biopsy specimen can be used before radical prostatectomy to predict biochemical failure.

Investigation of the safety and accuracy of intraoperative gamma probe directed biopsy of bone scan detected rib abnormalities in prostatic adenocarcinoma

PURPOSE

We evaluated the technique of intraoperative gamma probe directed rib biopsy in patients with suspected metastatic prostate adenocarcinoma. This technique can be used to identify accurately the rib in question, reliably obtain sufficient tissue for diagnosis, be performed with minimal patient morbidity and potentially alter the course of therapy.

MATERIALS AND METHODS

From 1996 to 2001, 8 patients with biopsy proved adenocarcinoma of the prostate and suspicious rib lesions on radionuclide bone scanning underwent open rib biopsy as part of the evaluation for metastatic disease. Mean prostate specific antigen in the patient population was 17.1 ng/ml (range 6.1 to 36.5) and clinical stage was T1c to T3c. A new technique of intraoperative gamma probe directed biopsy was used to localize and resect the rib in question. At 6 to 12 hours before the operation each patient received an intravenous injection of 28 mCi. (99m)technetium-oxidronate. The hand held, pencil sized gamma probe in a sterile sleeve was used to localize the area of greatest activity in the target bone and 3 cm. of bone were resected.

RESULTS

Of the 8 patients who underwent the procedure 2 had metastatic prostate cancer on final rib pathological findings. Four of the remaining 5 patients had benign rib lesions (an old rib fracture) and 1 had metastatic lung cancer. The hot spot on bone scan was localized with 100% accuracy using our technique and a pathological diagnosis was made in all cases. Mean operative time was 61 minutes and estimated blood loss was less than 20 ml. in all cases. Seven of the 8 patients were discharged home the same day, while 1 required overnight hospitalization. There was 1 intraoperative complication of inadvertent entry into the pleural cavity, resulting in a small pneumothorax, which was treated with small chest catheter drainage and observation.

CONCLUSIONS

Intraoperative gamma probe directed rib biopsy of suspected metastatic lesions in patients with prostate cancer can be safely and accurately performed with minimal patient morbidity. The information obtained using this technique can be used to tailor treatment decisions for this subset of patients with prostate cancer.

Limited value of bone scintigraphy and computed tomography in assessing biochemical failure after radical prostatectomy

OBJECTIVES

To define the utility of bone scan and computed tomography (CT) in the evaluation of patients with biochemical recurrence after radical prostatectomy.

METHODS

A retrospective analysis of the Center for Prostate Disease Research database was undertaken to identify patients who underwent radical prostatectomy between 1989 and 1998. Patients who developed biochemical recurrence (two prostate-specific antigen [PSA] levels greater than 0.2 ng/mL) and underwent either bone scan or CT within 3 years of this recurrence were selected for analysis. The preoperative clinical parameters, pathologic findings, serum PSA levels, follow-up data, and radiographic results were reviewed.

RESULTS

One hundred thirty-two patients with biochemical recurrence and a bone scan or CT scan were identified. Of the 127 bone scans, 12 (9.4%) were positive. The patients with true-positive bone scans had an average PSA at the time of the bone scan of 61.3 +/- 71.2 ng/mL (range 1.3 to 123). Their PSA velocities, calculated from the PSA levels determined immediately before the radiographic studies, averaged 22.1 +/- 24.7 ng/mL/mo (range 0.14 to 60.0). Only 2 patients with a positive bone scan had a PSA velocity of less than 0.5 ng/mL/mo. Of the 86 CT scans, 12 (14.0%) were positive. On logistic regression analysis, PSA and PSA velocity predicted the bone scan result (P <0.001 each) and PSA velocity predicted the CT scan result (P = 0.047).

CONCLUSIONS

Patients with biochemical recurrence after radical prostatectomy have a low probability of a positive bone scan (9.4%) or a positive CT scan (14.0%) within 3 years of biochemical recurrence. Most patients with a positive bone scan have a high PSA level and a high PSA velocity (greater than 0.5 ng/mL/mo).