Active surveillance for prostate cancer: current evidence and contemporary state of practice

Development and External Validation of the Korean Prostate Cancer Risk Calculator for High-Grade Prostate Cancer: Comparison with Two Western Risk Calculators in an Asian Cohort

PURPOSE

We developed the Korean Prostate Cancer Risk Calculator for High-Grade Prostate Cancer (KPCRC-HG) that predicts the probability of prostate cancer (PC) of Gleason score 7 or higher at the initial prostate biopsy in a Korean cohort (http://acl.snu.ac.kr/PCRC/RISC/). In addition, KPCRC-HG was validated and compared with internet-based Western risk calculators in a validation cohort.

MATERIALS AND METHODS

Using a logistic regression model, KPCRC-HG was developed based on the data from 602 previously unscreened Korean men who underwent initial prostate biopsies. Using 2,313 cases in a validation cohort, KPCRC-HG was compared with the European Randomized Study of Screening for PC Risk Calculator for high-grade cancer (ERSPCRC-HG) and the Prostate Cancer Prevention Trial Risk Calculator 2.0 for high-grade cancer (PCPTRC-HG). The predictive accuracy was assessed using the area under the receiver operating characteristic curve (AUC) and calibration plots.

RESULTS

PC was detected in 172 (28.6%) men, 120 (19.9%) of whom had PC of Gleason score 7 or higher. Independent predictors included prostate-specific antigen levels, digital rectal examination findings, transrectal ultrasound findings, and prostate volume. The AUC of the KPCRC-HG (0.84) was higher than that of the PCPTRC-HG (0.79, p<0.001) but not different from that of the ERSPCRC-HG (0.83) on external validation. Calibration plots also revealed better performance of KPCRC-HG and ERSPCRC-HG than that of PCPTRC-HG on external validation. At a cut-off of 5% for KPCRC-HG, 253 of the 2,313 men (11%) would not have been biopsied, and 14 of the 614 PC cases with Gleason score 7 or higher (2%) would not have been diagnosed.

CONCLUSIONS

KPCRC-HG is the first web-based high-grade prostate cancer prediction model in Korea. It had higher predictive accuracy than PCPTRC-HG in a Korean population and showed similar performance with ERSPCRC-HG in a Korean population. This prediction model could help avoid unnecessary biopsy and reduce overdiagnosis and overtreatment in clinical settings.

Active Surveillance for Favorable Risk Prostate Cancer in African Caribbean Men: Results of a Prospective Study

PURPOSE

Active surveillance is a treatment option for favorable risk prostate cancer. However, data are missing on populations of African descent. We evaluated the safety and benefit of active surveillance in an African Caribbean cohort with favorable risk prostate cancer.

MATERIALS AND METHODS

Between 2005 and 2016, a single center, prospective cohort study was performed in Guadeloupe, French West Indies, including patients on active surveillance who had low risk prostate cancer (prostate specific antigen 10 ng/ml or less and Gleason score 6 or less) or favorable intermediate risk prostate cancer (prostate specific antigen 10 to 20 ng/ml, Gleason score 3 + 4 or less and life expectancy less than 10 years). Treatment was recommended in case of grade progression, increased tumor volume, prostate cancer doubling time less than 36 months or patient wish. Overall survival, disease specific survival and duration of active surveillance were calculated with the Kaplan-Meier method. Multivariate analysis was performed using the Cox proportional hazards model to identify predictors of active surveillance termination.

RESULTS

A total of 234 patients with a median age of 64 years were enrolled in study. Median followup was 4 years (IQR 2.3-5.5). Overall survival at 30 months, 5 years and 10 years was 99.5%, 98.5% and 90.7%, respectively. Disease specific survival at 30 months, and 5 and 10 years was 100%. At 30 months, 5 years and 10 years 72.7%, 52.6% and 40.4% of patients, respectively, remained untreated and on active surveillance. Age (HR 0.96 per additional year, 95% CI 0.93-0.99) and prostate specific antigen density (HR 1.52 per additional 0.1 ng/ml, 95% CI 1.20-1.89) were found to be independent predictors of active surveillance termination.

CONCLUSIONS

Active surveillance is safe and beneficial for highly selected African Caribbean patients. It seems to be feasible for patients at low risk and intermediate favorable risk. Prostate specific antigen density could help better select these patients.

Evaluation of predictors of unfavorable pathological features in men eligible for active surveillance using radical prostatectomy specimens: a multi-institutional study

OBJECTIVE

Active surveillance has emerged as an alternative to immediate treatment in men with favorable-risk prostate cancer; however, consensus about defining the appropriate candidates is still lacking. To examine the factors predicting unfavorable pathology among active surveillance candidates, we assessed low-risk radical prostatectomy specimens.

METHODS

This retrospective study included 1753 men who had undergone radical prostatectomy at six independent institutions in Japan from 2005 to 2011. Patients who met the active surveillance criteria were categorized depending on the pathological features of the radical prostatectomy specimens. 'Reclassification' was defined as upstaging (≥pT3) or upgrading (radical prostatectomy Gleason score ≥7), and 'adverse pathology' was defined as pathological stage ≥pT3 or radical prostatectomy Gleason score ≥4 + 3. Multivariate analysis was used to analyze the preoperative factors for reclassification and adverse pathology. The rates of reclassification and adverse pathology were evaluated by classifying patients according to biopsy core numbers.

RESULTS

The active surveillance criteria were met by 284 cases. Reclassification was identified in 154 (54.2%) cases, while adverse pathology in 60 (21.1%) cases. Prostate-specific antigen density and percentage of positive cores were independently associated with reclassification and adverse pathology. The rates of reclassification and adverse pathology were significantly higher among patients with <10 biopsy cores than among others. Thus, focusing on 149 patients with ≥10 biopsy cores, prostate-specific antigen density was the only independent predictor of unfavorable pathological features. The receiver operating characteristic curve analysis determines an optimal cut-off value of prostate-specific antigen density as 0.15 ng/ml².

CONCLUSIONS

Prostate-specific antigen density is the most important predictor of unfavorable pathological features in active surveillance candidates.

Qualitative study on decision-making by prostate cancer physicians during active surveillance

OBJECTIVE

To explore and identify factors that influence physicians' decisions while monitoring patients with prostate cancer on active surveillance (AS).

SUBJECTS AND METHODS

A purposive sampling strategy was used to identify physicians treating prostate cancer from diverse clinical backgrounds and geographic areas across the USA. We conducted 24 in-depth interviews from July to December 2015, until thematic saturation was reached. The Applied Thematic Analysis framework was used to guide data collection and analysis. Interview transcripts were reviewed and coded independently by two researchers. Matrix analysis and NVivo software were used for organization and further analysis.

RESULTS

Eight key themes emerged to explain variation in AS monitoring: (i) physician comfort with AS; (ii) protocol selection; (iii) beliefs about the utility and quality of testing; (iv) years of experience and exposure to AS during training; (v) concerns about inflicting 'harm'; (vi) patient characteristics; (vii) patient preferences; and (viii) financial incentives.

CONCLUSION

These qualitative data reveal which factors influence physicians who manage patients on AS. There is tension between providing standardized care while also considering individual patients' needs and health status. Additional education on AS is needed during urology training and continuing medical education. Future research is needed to empirically understand whether any specific protocol is superior to tailored, individualized care.

Active Surveillance for Intermediate Risk Prostate Cancer: Survival Outcomes in the Sunnybrook Experience

PURPOSE

To assess the applicability of active surveillance in patients with intermediate risk prostate cancer, we compared the survival outcomes of patients with low risk and intermediate risk disease.

MATERIALS AND METHODS

Active surveillance was offered to all patients with low risk (cT1-T2b and Gleason score 6 and prostate specific antigen 10 ng/ml or less) and select intermediate risk disease (age greater than 70 years with cT2c or prostate specific antigen 15 ng/ml or less, or Gleason score 3+4 or less). Data from November 1995 to May 2013 were extracted from a prospectively collected database. The primary outcome was metastasis-free survival, and secondary outcomes were overall survival, cause specific survival and treatment-free survival.

RESULTS

A total of 213 intermediate risk and 732 low risk cases were identified. Median age was 72 years (IQR 67.3, 76.8) in the intermediate risk cohort and 67 years (IQR 60.6, 71.9) in the low risk group. Median followup was comparable (6.7 years for intermediate risk vs 6.5 years for low risk). Gleason 7 disease comprised 60% of the intermediate risk cohort. The 15-year metastasis-free, overall, cause specific and treatment-free survival rates were inferior in the intermediate risk group (metastasis-free survival HR 3.14, 95% CI 1.51-6.53, p=0.001, 82% for intermediate risk vs 95% for low risk). On further evaluation the estimated 15-year metastasis-free survival for cases of Gleason 6 or less with prostate specific antigen less than 10 ng/ml was 94%, Gleason 6 or less with prostate specific antigen 10 to 20 ng/ml was 94%, Gleason 3+4 with prostate specific antigen 20 ng/ml or less was 84% and Gleason 4+3 with prostate specific antigen 20 ng/ml or less was 63%.

CONCLUSIONS

These data support the use of active surveillance in low risk and intermediate risk cases of Gleason 6 but not Gleason 7 prostate cancer. Multiparametric magnetic resonance imaging and novel biomarkers might be vital in detecting favorable Gleason 7 disease.

Prediction of pathological stage based on clinical stage, serum prostate-specific antigen, and biopsy Gleason score: Partin Tables in the contemporary era

OBJECTIVE

To update the Partin Tables for prediction of pathological stage in the contemporary setting and examine trends in patients treated with radical prostatectomy (RP) over the past three decades.

PATIENTS AND METHODS

From January 2010 to October 2015, 4459 men meeting inclusion criteria underwent RP and pelvic lymphadenectomy for histologically confirmed prostate cancer at the Johns Hopkins Hospital. Preoperative clinical stage, serum prostate-specific antigen (PSA) level, and biopsy Gleason score (i.e. prognostic Grade Group) were used in a polychotomous logistic regression model to predict the probability of pathological outcomes categorised as: organ-confined (OC), extraprostatic extension (EPE), seminal vesicle involvement (SV+), or lymph node involvement (LN+). Preoperative characteristics and pathological findings in men treated with RP since 1983 were collected and clinical-pathological trends were described.

RESULTS

The median (range) age at surgery was 60 (34-77) years and the median (range) PSA level was 4.9 (0.1-125.0) ng/mL. The observed probabilities of pathological outcomes were: OC disease in 74%, EPE in 20%, SV+ in 4%, and LN+ in 2%. The probability of EPE increased substantially when biopsy Gleason score increased from 6 (Grade Group 1, GG1) to 3 + 4 (GG2), with smaller increases for higher grades. The probability of LN+ was substantially higher for biopsy Gleason score 9-10 (GG5) as compared to lower Gleason scores. Area under the receiver operating characteristic curves for binary logistic models predicting EPE, SV+, and LN+ vs OC were 0.724, 0.856, and 0.918, respectively. The proportion of men treated with biopsy Gleason score ≤6 cancer (GG1) was 47%, representing a substantial decrease from 63% in the previous cohort and 77% in 2000-2005. The proportion of men with OC cancer has remained similar during that time, equalling 73-74% overall. The proportions of men with SV+ (4.1% from 3.4%) and LN+ (2.3% from 1.4%) increased relative to the preceding era for the first time since the Partin Tables were introduced in 1993.

CONCLUSIONS

The Partin Tables remain a straightforward and accurate approach for projecting pathological outcomes based on readily available clinical data. Acknowledging these data are derived from a tertiary care referral centre, the proportion of men with OC disease has remained stable since 2000, despite a substantial decline in the proportion of men with biopsy Gleason score 6 (GG1). This is consistent with the notion that many men with Gleason score 6 (GG1) disease were over treated in previous eras.

Risk stratification of prostate cancer: integrating multiparametric MRI, nomograms and biomarkers

Accurate risk stratification of prostate cancer is achieved with a number of existing tools to ensure the identification of at-risk patients, characterization of disease aggressiveness, prediction of cancer burden and extrapolation of treatment outcomes for appropriate management of the disease. Statistical tables and nomograms using classic clinicopathological variables have long been the standard of care. However, the introduction of multiparametric MRI, along with fusion-guided targeted prostate biopsy and novel biomarkers, are being assimilated into clinical practice. The majority of studies to date present the outcomes of each in isolation. The current review offers a critical and objective assessment regarding the integration of multiparametric MRI and fusion-guided prostate biopsy with novel biomarkers and predictive nomograms in contemporary clinical practice.

Comparison of Pathological Outcomes for Men with Low Risk Prostate Cancer from Diverse Practice Settings: Similar Results from Immediate Prostatectomy or Initial Surveillance with Delayed Prostatectomy

PURPOSE

We compared pathological outcomes after radical prostatectomy for a population based sample of men with low risk prostate cancer initially on active surveillance and undergoing delayed prostatectomy vs those treated with immediate surgery in order to better understand this expectant management approach outside of the context of academic cohorts. We hypothesized that delays in surgery due to initial surveillance would not impact surgical pathological outcomes.

MATERIALS AND METHODS

We performed a prospective cohort study of 2 groups of patients with NCCN low risk prostate cancer from practices in the Michigan Urological Surgery Improvement Collaborative, that is 1) men who chose initial active surveillance and went on to delayed prostatectomy and 2) men who chose immediate prostatectomy. Diagnoses occurred from January 2011 through August 2015. For these 2 groups we compared radical prostatectomy Gleason scores, and rates of extraprostatic disease, positive surgical margins, seminal vesicle invasion and lymph node metastases.

RESULTS

During a median followup of 506 days 79 (6%) of 1,359 low risk men choosing initial surveillance transitioned to prostatectomy. Compared to those treated with immediate prostatectomy (778), men undergoing delayed surgery were more likely to have Gleason score 7 or greater disease (69.2% vs 48.8%, respectively, p=0.004), but were no more likely to have positive margins, extraprostatic extension, seminal vesicle invasion or lymph node metastases.

CONCLUSIONS

Patients with low risk prostate cancer who enter active surveillance have higher grade disease at prostatectomy compared to those undergoing immediate surgery. However, the lack of difference in other adverse pathological outcomes suggests preservation of the window of curability.

Active Surveillance of Prostate Cancer: Use, Outcomes, Imaging, and Diagnostic Tools

Active surveillance (AS) has emerged as a standard management option for men with very low-risk and low-risk prostate cancer, and contemporary data indicate that use of AS is increasing in the United States and abroad. In the favorable-risk population, reports from multiple prospective cohorts indicate a less than 1% likelihood of metastatic disease and prostate cancer-specific mortality over intermediate-term follow-up (median 5-6 years). Higher-risk men participating in AS appear to be at increased risk of adverse outcomes, but these populations have not been adequately studied to this point. Although monitoring on AS largely relies on serial prostate biopsy, a procedure associated with considerable morbidity, there is a need for improved diagnostic tools for patient selection and monitoring. Revisions from the 2014 International Society of Urologic Pathology consensus conference have yielded a more intuitive reporting system and detailed reporting of low-intermediate grade tumors, which should facilitate the practice of AS. Meanwhile, emerging modalities such as multiparametric magnetic resonance imaging and tissue-based molecular testing have shown prognostic value in some populations. At this time, however, these instruments have not been sufficiently studied to consider their routine, standardized use in the AS setting. Future studies should seek to identify those platforms most informative in the AS population and propose a strategy by which promising diagnostic tools can be safely and efficiently incorporated into clinical practice.