The Cancer of the Prostate Risk Assessment (CAPRA) in patients treated with external beam radiation therapy: Evaluation and optimization in patients at higher risk of relapse

Validation of the Combination Gleason Score as an Independent Favorable Prognostic Factor in Prostate Cancer Treated With Dose-Escalated Radiation Therapy

PURPOSE

Prognostic factors for prostate cancer include tumor, node, metastases stage, pretreatment prostate-specific antigen, and pathology (via Gleason score [GS] or grade group). Of these, GS yields the largest effect on prostate cancer specific mortality. It was previously determined that those with cores with a mix of higher and lower GS at biopsy (which was termed a "ComboGS") had decreased risk for prostate cancer specific mortality after either surgical or radiation treatment. We validate the effect of ComboGS in an independent cohort of patients with prostate cancer treated with definitive dose-escalated radiation therapy (DE-RT) at 2 institutions.

METHODS AND MATERIALS

DE-RT was administered to 2539 men, of which 687 men had a ComboGS. To further ascertain the ComboGS effect we employed the modified Cancer of the Prostate Risk Assessment (mCAPRA) score. Rates of biochemical event-free survival and distant metastasis-free survival were compared across CAPRA scores, with and without modification, and the prognostic value of the CAPRA scores was compared using Harrel's concordance index.

RESULTS

On univariate analysis in Gleason 7 to 10 patients the presence of ComboGS improved 10-year biochemical event-free survival from 76.6% to 82.4% (hazard ratio [HR], 0.75; confidence interval [CI], 0.59-0.96; P = .021), 10-year distant metastasis-free survival from 89.3% to 93.2% (HR, 0.57; CI, 0.39-0.85; P = .005), 10-year prostate cancer specific survival from 93.9% to 97.4% (HR, 0.39; CI, 0.21-0.7; P = .001), and 10-year overall survival from 65.7% to 75.6% (HR, 0.69; CI, 0.57-0.83; P < .001). Multivariable analysis also supported that ComboGS is protective for biochemical failure (HR, 0.64; CI, 0.50-0.83; P < .001), distant metastasis (HR, 0.42; CI, 0.28-0.63; P < .001), death from prostate cancer (HR, 0.32; CI, 0.17-0.58; P < .001), and overall mortality (HR, 0.65; CI, 0.54-0.79; P < .001). Additionally, adjusting the mCAPRA score for ComboGS decreased the risk of biochemical failure by nearly 30% (HR, 0.70; 95% CI, 0.55-0.88; P = .003) and by 50% (HR, 0.54; 95% CI, 0.37-0.80; P = .002) for distant metastasis.

CONCLUSIONS

ComboGS is a useful and readily available independent prognostic factor for all clinical endpoints evaluated. Moreover, the ComboGS can be used in conjunction with the extensively validated CAPRA scoring to better risk stratify patients being treated with definitive DE-RT for GS 7 to 10 disease.

External beam radiation therapy treatment factors prognostic of biochemical failure free survival: a multi-institutional retrospective study for prostate cancer

BACKGROUND AND PURPOSE

The goal of this work is to identify specific treatment planning and delivery features that are prognostic of biochemical failure-free survival (BFFS) for prostate cancer patients treated with external beam radiotherapy (EBRT).

MATERIALS AND METHODS

This study reviewed patients diagnosed with localized prostate adenocarcinoma between 2005 and 2016, and treated with EBRT on a Varian linear accelerator at one of the four cancer centers in Alberta, Canada. BFFS was calculated using the Kaplan-Meier estimator. Patient demographics, tumor characteristics, and EBRT treatment planning and delivery factors, were collected for each patient. The patient cohort was split into a training dataset with patients from two centers and a validation dataset with patients from another two centers. A random survival forest was used to identify features associated with BFFS.

RESULTS

This study included 2827 patients with a median follow-up of 6.4 years. The BFFS for this cohort collectively was 84.9% at 5 years and 69.3% at 10 years. 2519 patients from two centers were used for model training and 308 patients from two different centers were used for model validation. The prognostic features were Gleason score, prostate-specific antigen (PSA) at diagnosis, clinical T stage, CTV D99, pelvic irradiation, IGRT frequency, and PTV V98. Variables including bladder volume, dose calculation algorithm, PTV D99, age at diagnosis, hip prosthesis, number of malignancies, fiducial marker usage, PTV volume, RT modality, PTV HI, rectal volume, hormone treatment, PTV D1cc, equivalent PTV margin, IGRT type, and EQD2_1.5 were unlikely to be prognostic. A random survival forest using only the seven prognostic variables was built. The Harrell's concordance index for the model was 0.65 for the whole training dataset, 0.62 for out-of-bag samples of the training dataset, and 0.62 for the validation dataset.

CONCLUSION

EBRT features prognostic of BFFS were identified and a random survival forest was developed for predicting prostate cancer patients' BFFS after EBRT.

The CAPRA score versus sub-types of minimal residual disease to predict biochemical failure after external beam radiotherapy

Introduction

External beam radiotherapy is a treatment option for clinically localised prostate cancer; however, some 15% of patients will undergo treatment failure within 5 years. The objective was to compare the Cancer of the Prostate Risk Assessment (CAPRA) score (based on the clinical-pathological findings) and the sub-types of minimal residual disease (MRD) (based on the biological properties of the cancer cells) risk classifications to predict biochemical failure (BF) after external beam radiotherapy.

Methods and Patients

Clinical-pathological findings were obtained from the prostate biopsy to determine the CAPRA score and used to define low-, intermediate- and high-risk patients. Blood and bone marrow were obtained 3 months after radiotherapy; circulating prostate cells (CPCs) and micro-metastasis were detected using immunocytochemistry with anti-prostate specific antigen. CPCs and micro-metastasis were classified as positive if at least one cell was detected in the sample. Three subgroups were formed Group A (MRD negative), Group B (micro-metastasis positive, CPC negative) and Group C (CPC positive)Patients were followed up for 10 years or until biochemical failure. Biochemical failure free survival (BFFS) curves were constructed using Kaplan-Meier (observed), a flexible parameter model (predicted survival) and the restricted mean survival time (RMST) was calculated for each sub-group.

Results

309 men participated with a median follow-up of 8 years. The risk of biochemical failure increased proportionally with increasing CAPRA score, hazard ratio 1.18 for intermediate and 1.69 for high risk patients. After 10 years, the percentage BFFS and RMST to failure were 74%, 49%, 16% and 9, 7 and 6 years, respectively. The agreement between observed and predicted BFFS was acceptable (Harrell´s C 0.62). The BFFS curves for MRD were different and not proportional, survival curves for men MRD negative and only micro-metastasis were similar up to 5 years, and then there was increasing failure in the micro-metastasis only group. After 10 years, the percentage BFFS and RMST to failure were 95%, 59%, 28% and 10, 9 and 6 years, respectively. The CAPRA score failed to distinguish between Groups A and B, one third of high risk Group C had low risk CAPRA scores. The agreement between observed and predicted BFFS was very good (Harrell´s C 0.92). Minimal residual disease hazard ratios were Group B 1.84 and Group C 4.51.

Conclusions

The MRD prognostic classification is based on the biological characteristics of the tumour cell-microenvironment interaction, to give three groups, MRD negative, only bone marrow micro-metastasis and CPC positive prostate cancer. Differing from the CAPRA score classification the risk of treatment failure changes with time, differentiating between early and late treatment failures and incorporates the concept of dormancy. It proved to be superior to the CAPRA score in predicting biochemical failure and the results need to be confirmed in larger studies.

Whom to Treat: Postdiagnostic Risk Assessment with Gleason Score, Risk Models, and Genomic Classifier

Management of prostate cancer presents unique challenges because of the disease's variable natural history. Accurate risk stratification at the time of diagnosis in clinically localized disease is crucial in providing optimal counseling about management options. To accurately distinguish pathologically indolent tumors from aggressive disease, risk groups are no longer sufficient. Rather, multivariable prognostic models reflecting the complete information known at time of diagnosis offer improved accuracy and interpretability. After diagnosis, further testing with genomic assays or other biomarkers improves risk classification. These postdiagnostic risk assessment tools should not supplant shared decision making, but rather facilitate risk classification and enable more individualized care.

An appraisal of analytical tools used in predicting clinical outcomes following radiation therapy treatment of men with prostate cancer: a systematic review

Background

Prostate cancer can be treated with several different modalities, including radiation treatment. Various prognostic tools have been developed to aid decision making by providing estimates of the probability of different outcomes. Such tools have been demonstrated to have better prognostic accuracy than clinical judgment alone.

Methods

A systematic review was undertaken to identify papers relating to the prediction of clinical outcomes (biochemical failure, metastasis, survival) in patients with prostate cancer who received radiation treatment, with the particular aim of identifying whether published tools are adequately developed, validated, and provide accurate predictions. PubMed and EMBASE were searched from July 2007. Title and abstract screening, full text review, and critical appraisal were conducted by two reviewers. A review protocol was published in advance of commencing literature searches.

Results

The search strategy resulted in 165 potential articles, of which 72 were selected for full text review and 47 ultimately included. These papers described 66 models which were newly developed and 31 which were external validations of already published predictive tools. The included studies represented a total of 60,457 patients, recruited between 1984 and 2009. Sixty five percent of models were not externally validated, 57% did not report accuracy and 31% included variables which are not readily accessible in existing datasets. Most models (72, 74%) related to external beam radiation therapy with the remainder relating to brachytherapy (alone or in combination with external beam radiation therapy).

Conclusions

A large number of prognostic models (97) have been described in the recent literature, representing a rapid increase since previous reviews (17 papers, 1966–2007). Most models described were not validated and a third utilised variables which are not readily accessible in existing data collections. Where validation had occurred, it was often limited to data taken from single institutes in the US. While validated and accurate models are available to predict prostate cancer specific mortality following external beam radiation therapy, there is a scarcity of such tools relating to brachytherapy. This review provides an accessible catalogue of predictive tools for current use and which should be prioritised for future validation.

Electronic supplementary material

The online version of this article (doi:10.1186/s13014-017-0786-z) contains supplementary material, which is available to authorized users.

Limitations of the Cancer of the Prostate Risk Assessment (CAPRA) Prognostic Tool for Prediction of Metastases and Prostate Cancer-specific Mortality in Patients Treated With External Beam Radiation Therapy

OBJECTIVES

To assess the performance of the Cancer of the Prostate Risk Assessment (CAPRA) prognostic tool for freedom-from-metastases (FFM) and cause-specific survival (CSS) in patients with localized prostate cancer treated with definitive external beam radiotherapy (EBRT), and to determine whether the performance of CAPRA is influenced by androgen deprivation therapy (ADT) use or the presence of Gleason pattern 5 (GP-5).

MATERIALS AND METHODS

A total of 612 patients from a prospective database of 718 patients treated with dose-escalated EBRT from 1998 to 2008 who met CAPRA scoring criteria were included in the study. Performance of CAPRA and association of CAPRA score, GP-5 and short-term or long-term ADT use (STAD or LTAD, respectively) with FFM and CSS were evaluated using Cox models. The impact of ADT use on accuracy of the CAPRA-based CaPSURE model for CSS was assessed. The discriminatory ability of the CAPRA model and modified models incorporating GP-5 and ADT use were compared using the C-index.

RESULTS

Increasing CAPRA score correlated with worse FFM and CSS, and was prognostic for FFM and CSS for the overall cohort. CAPRA showed poorer discrimination for FFM and CSS in patients treated with EBRT+LTAD than those who received EBRT alone or EBRT+STAD. The addition of GP-5 and ADT use to CAPRA score increased the predictive accuracy of the CAPRA model for both FFM (C-index 0.809 vs. 0.779, P<0.001) and CSS (C-index 0.864 vs. 0.796, P=0.003).

CONCLUSIONS

The CAPRA score should be modified to incorporate GP-5 and ADT use for risk adjustment and risk prediction in prostate cancer patients who receive EBRT.

Radioprotective effect of calcium channel blockers against late rectal bleeding in prostate cancer

OBJECTIVE

This study was done to assess the impact of clinical factors and in particular the use of drugs for concomitant illnesses on late radiation-induced rectal bleeding in patients with prostate cancer.

MATERIALS AND METHODS

Patients with histologically proven prostate adenocarcinoma treated with radical radiotherapy and followed up for at least 6 months were selected. The correlation between late rectal bleeding and a number of factors was investigated by univariate and multivariate analysis.

RESULTS

A total of 278 patients who underwent radiotherapy at our institution between October 2002 and May 2011 were selected. At univariate analysis, delivery of radiation doses higher than 70 Gy and use of angiotensin-converting enzyme inhibitors were associated with a higher incidence of rectal bleeding. Conversely, patients who used calcium channel blockers had a lower risk (3-year rectal bleeding-free survival 89.8 versus 66.5 %, p = 0.043). At multivariate analysis, use of calcium channel blockers was found to have a protective effect with a hazard ratio of 0.3 (95 % CI 0.12-0.96). Delivery of higher radiation doses was associated with an increased risk of rectal bleeding (hazard ratio 3.02, 95 % CI 1.23-7.38).

CONCLUSIONS

Use of calcium channel blockers during and after radiotherapy treatment might have a protective effect against late rectal bleeding. If these results are reconfirmed by larger clinical series, calcium channel blockers may be tested as radioprotector agents in clinical trials.

Prognostic value of the CAPRA clinical prediction rule: a systematic review and meta-analysis

WHAT'S KNOWN ON THE SUBJECT? AND WHAT DOES THE STUDY ADD?: Prostate cancer is a significant cause of mortality among men. A number of prognostic instruments exist to predict the risk of recurrence among patients with localised prostate cancer. This systematic review examines the totality of evidence in relation to the predictive value of the CAPRA clinical predication rule by combining all studies that validate the rule.

OBJECTIVES

To perform a systematic review with meta-analysis that assesses the 3- and 5-year predictive value of the CAPRA rule, a clinical prediction rule derived to predict biochemical-recurrence-free survival in men with localized prostate cancer after radical prostatectomy. To examine the predictive value of the CAPRA rule at 3 and 5 years stratified by risk group (0-2 low risk, 3-5 intermediate risk, 6-10 high risk).

PATIENTS AND METHODS

A systematic literature search was performed to retrieve papers that validated the CAPRA score. The original derivation study was used as a predictive model and applied to all validation studies with observed and predicted biochemical-recurrence-free survival at 3 and 5 years stratified by risk group (0-2 low, 3-5 intermediate, 6-10 high). Pooled results are presented as risk ratios (RRs) with 95% confidence intervals, in terms of over-prediction (RR > 1) or under-prediction (RR < 1) of biochemical-recurrence-free survival at 3 and 5 years. A chi-squared test for trend was computed to determine if there was a decreasing trend in survival across the three CAPRA risk categories.

RESULTS

Seven validation studies (n = 12 693) predict recurrence-free survival at 5 years after radical prostatectomy. The CAPRA score significantly under-predicts recurrence-free survival across all three risk strata (low risk, RR 0.94, 95% CI 0.90-0.98; intermediate risk, RR 0.94, 95% CI 0.89-0.99; high risk, RR 0.72, 95% CI 0.60-0.85). Data on six studies (n = 6082) are pooled to predict 3-year recurrence-free survival. The CAPRA score correctly predicts recurrence-free survival in all three groups (low risk, RR 0.98, 95% CI 0.95-1.00; intermediate risk, RR 1.03, 95% CI 0.99-1.08; high risk, RR 0.87, 95% CI 0.73-1.05). The chi-squared trend analysis indicates that, as the trichotomized CAPRA score increases, the probability of survival decreases (P < 0.001).

CONCLUSIONS

The results of this pooled analysis confirm the ability of the CAPRA rule to correctly predict biochemical-recurrence-free survival at 3 years after radical prostatectomy. The rule under-predicts recurrence-free survival 5 years after radical prostatectomy across all three strata of risk.