Results of a surgically derived nomogram to predict Gleason score upgrading applied to a cohort of patients with "favorable-risk" prostate cancer treated with permanent seed brachytherapy

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.

Gleason group concordance between biopsy and radical prostatectomy specimens: A cohort study from Prostate Cancer Outcome Registry - Victoria

Background

A new prostate cancer (PCa) prognostic grading system [Gleason groups (GGs)] has been proposed based on the contemporary Gleason scores (GSs), which has five simplified prognostic categories. The objective of this study was to evaluate the agreement between the GGs of prostate biopsy and radical prostatectomy specimens and to identify predictive factors for upgrading GGs.

Methods

A total of 5339 cases of RP notified to the Prostate Cancer Outcomes Registry, Victoria, Australia over 6 years (2009–2014) from 46 hospitals, were included. The upgrading was evaluated using the new PCa prognostic grading system, the International Society of Urologic Pathology grade groups, which has five prognostic categories. GG 1 is GS ≤ 6, GG 2 is GS 3 + 4 = 7, GG 3 is GS 4 + 3 = 7, GG 4 is GS 8, and GG 5 is GS 9 and 10. Predictors of upgrading were assessed using univariate and multivariate models.

Results

The GG of prostate biopsies and RP specimens were concordant in 54.5% of cases, while 31.1% were upgraded and 14.3% were downgraded. Longer time interval between biopsy and RP [44–99 days: odds ratio (OR) = 1.3, 95% confidence interval (CI) = 1.1–1.6; > 99 days: OR = 3.0, 95% CI = 2.4–3.8), and RP performed in a metropolitan hospital (biopsy in a regional hospital: OR = 2.2, 95% CI = 1.6–3.2, biopsy in a metropolitan hospital: OR = 1.7, 95% CI = 1.2–2.2) were significant predictors of GG upgrading. Patients who were diagnosed by transperineal biopsy compared to transrectal ultrasound (OR = 0.6, 95% CI = 0.5–0.8) and higher percentage of positive biopsy cassettes (25–62.5%: OR = 0.7, 95% CI = 0.6–0.8, > 62.5: OR = 0.6, 95% CI = 0.5–0.8) were significantly associated with less likelihood of upgrade.

Conclusion

The lack of concordance among hospitals may be attributable to the specialist expertise of the pathologist. Expert review of specimens may help to overcome this discordance. Clinicians should consider clinical parameters and potential limitations of the GG at biopsy when making treatment decisions with regard to PCa.

Development of ProCaRS Clinical Nomograms for Biochemical Failure-free Survival Following Either Low-Dose Rate Brachytherapy or Conventionally Fractionated External Beam Radiation Therapy for Localized Prostate Cancer

Purpose: Although several clinical nomograms predictive of biochemical failure-free survival (BFFS) for localized prostate cancer exist in the medical literature, making valid comparisons can be challenging due to variable definitions of biochemical failure, the disparate distribution of prognostic factors, and received treatments in patient populations. The aim of this investigation was to develop and validate clinically-based nomograms for 5-year BFFS using the ASTRO II “Phoenix” definition for two patient cohorts receiving low-dose rate (LDR) brachytherapy or conventionally fractionated external beam radiation therapy (EBRT) from a large Canadian multi-institutional database.

Methods and Materials: Patients were selected from the GUROC (Genitourinary Radiation Oncologists of Canada) Prostate Cancer Risk Stratification (ProCaRS) database if they received (1) LDR brachytherapy ≥ 144 Gy (n=4208) or (2) EBRT ≥ 70 Gy  (n=822). Multivariable Cox regression analysis for BFFS was performed separately for each cohort and used to generate clinical nomograms predictive of 5-year BFFS. Nomograms were validated using calibration plots of nomogram predicted probability versus observed probability via Kaplan-Meier estimates.

Results: Patients receiving LDR brachytherapy had a mean age of 64 ± 7 years, a mean baseline PSA of 6.3 ± 3.0 ng/mL, 75% had a Gleason 6, and 15% had a Gleason 7, whereas patients receiving EBRT had a mean age of 70 ± 6 years, a mean baseline PSA of 11.6 ± 10.7 ng/mL, 30% had a Gleason 6, 55% had a Gleason 7, and 14% had a Gleason 8-10. Nomograms for 5-year BFFS included age, use and duration of androgen deprivation therapy (ADT), baseline PSA, T stage, and Gleason score for LDR brachytherapy and an ADT (months), baseline PSA, Gleason score, and biological effective dose (Gy) for EBRT.

Conclusions: Clinical nomograms examining 5-year BFFS were developed for patients receiving either LDR brachytherapy or conventionally fractionated EBRT and may assist clinicians in predicting an outcome. Future work should be directed at examining the role of additional prognostic factors, comorbidities, and toxicity in predicting survival outcomes.

Relationship between two year PSA nadir and biochemical recurrence in prostate cancer patients treated with iodine-125 brachytherap

Objective

To evaluate the relationship between two year PSA nadir (PSAn) after brachytherapy and biochemical recurrence rates in prostate cancer patients.

Materials and Methods

In the period from January 1998 to August 2007, 120 patients were treated with iodine-125 brachytherapy alone. The results analysis was based on the definition of biochemical recurrence according to the Phoenix Consensus.

Results

Biochemical control was observed in 86 patients (71.7%), and biochemical recurrence, in 34 (28.3%). Mean PSAn was 0.53 ng/ml. The mean follow-up was 98 months. The patients were divided into two groups: group 1, with two year PSAn < 0.5 ng/ml after brachytherapy (74 patients; 61.7%), and group 2, with two year PSAn ≥ 0.5 ng/ml after brachytherapy (46 patients; 38.3%). Group 1 presented biochemical recurrence in 15 patients (20.3%), and group 2, in 19 patients (43.2%) (p < 0.02). The analysis of biochemical disease-free survival at seven years, stratified by the two groups, showed values of 80% and 64% (p < 0.02), respectively.

Conclusion

Levels of two year PSAn ≥ 0.5 ng/ml after brachytherapy are strongly correlated with a poor prognosis. This fact may help to identify patients at risk for disease recurrence.

The effect of differing Gleason scores at biopsy on the odds of upgrading and the risk of death from prostate cancer

INTRODUCTION/BACKGROUND

The GS is an established prostate cancer prognostic factor. Whether the presence of differing GSs at biopsy (eg, 4+3 and 3+3), which we term ComboGS, improves the prognosis that would be predicted based on the highest GS (eg, 4+3) because of decreased upgrading is unknown. Therefore, we evaluated the odds of upgrading at time of radical prostatectomy (RP) and the risk of PCSM when ComboGS was present versus absent.

PATIENTS AND METHODS

Logistic and competing risks regression were performed to assess the effect that ComboGS had on the odds of upgrading at time of RP in the index (n = 134) and validation cohorts (n = 356) and the risk of PCSM after definitive therapy in a long-term cohort (n = 666), adjusting for known predictors of these end points. We calculated and compared the area under the curve using a receiver operating characteristic analysis when ComboGS was included versus excluded from the upgrading models.

RESULTS

ComboGS was associated with decreased odds of upgrading (index: adjusted odds ratio [AOR], 0.14; 95% confidence interval [CI], 0.04-0.50; P = .003; validation: AOR, 0.24; 95% CI, 0.11-0.51; P < .001) and added significantly to the predictive value of upgrading for the in-sample index (P = .02), validation (P = .003), and out-of-sample prediction models (P = .002). ComboGS was also associated with a decreased risk of PCSM (adjusted hazard ratio, 0.40; 95% CI, 0.19-0.85; P = .02).

CONCLUSION

Differing biopsy GSs are associated with a lower odds of upgrading and risk of PCSM. If validated, future randomized noninferiority studies evaluating deescalated treatment approaches in men with ComboGS could be considered.

PSA-nadir at 1 year as a sound contemporary prognostic factor for low-dose-rate iodine-125 seeds brachytherapy

OBJECTIVES

To identify predictors of outcomes in patients with localized prostate cancer treated with iodine-125 brachytherapy in a longitudinal uncontrolled study.

METHODS

Between 2000 and 2011, 560 histologically confirmed patients were treated with brachytherapy of whom 305 with ≥24-month follow-up and localized tumor were evaluated after exclusion of those locally advanced and under androgen ablation.

RESULTS

Patients' mean age was 63.93 years (44-88), mean pretreatment prostate-specific antigen (PSA) was 6.34 ng/mL (0.67-33.09), overall median follow-up was 75.35 months (24-158.37), biochemical recurrence occurred in 17 patients (5.57 %), cancer-specific survival was 100 %, and overall survival was 98.03 %. At multivariate analyses, only PSA-nadir at 1 year and age were related to disease-free survival: To each unit of PSA-nadir, the risk increases 87.3 %-OR 1.87 (p < 0.001; 95 % CI 1.31-2.67), and risk was 4.7 times higher for those under 50 years (vs. >70)-OR 4.69 (p = 0.04; 95 % CI 1.39-18.47). Best cutoff for PSA-nadir at one year was 0.285 (AUC = 0.78; p < 0.001; 95 % CI 0.68-0.89). Kaplan-Meier analysis confirmed PSA-nadir (p < 0.001) as prognostic, while D'Amico's classification failed (p = 0.24). No grade 3 or 4 complication was reported, and only 31.4 % of patients had grade 2 urinary or rectal toxicity. PSA bounce ≥0.4 ng/mL occurred in 18.4 % with no impact on biochemical recurrence.

CONCLUSIONS

Half (50.49 %) of patients in the scenario of localized prostate cancer treated with iodine-125 brachytherapy reach PSA-nadir at 1 year <0.285, recognized as a key independent prognostic factor.