Page 5 - CUA2018 Abstracts - Oncology-Prostate

Poster session 1: Prostate Cancer I

MP–1.3 was supplemented by expert consensus opinion in areas where evidence
A quantitative assessment of residual confounding in the was lacking. This led to the development of an algorithm (Fig. 1; available
comparison between surgery and radiotherapy in the treatment at https://cua.guide/) that provides practice guidance on the definition
of non–metastatic prostate cancer of biochemical failure, when to refer for local salvage options, recom-
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Christopher Wallis , Raj Satkunasivam , Sender Herschorn , Calvin Law , mended prostate–specific antigen (PSA) thresholds for use of intermittent
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Arun Seth , Ronald Kodama , Girish Kulkarni , Robert Nam 1 and continuous androgen–deprivation therapy (ADT), and the use of PSA
1 Urology, University of Toronto, Toronto, ON, Canada; Urology, Houston doubling time to guide frequency of laboratory and imaging investigations
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Methodist Hospital, Houston, TX, United States; General Surgery, once patients have developed castrate–resistant prostate cancer.
University of Toronto, Toronto, ON, Canada; Anatomic Pathology, Conclusions: With the ever–changing prostate cancer treatment land-
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Sunnybrook Health Sciences Centre, Toronto, ON, Canada scape and the trend to earlier use of systemic therapy, physicians are
Introduction: Observational comparisons of surgery and radiotherapy as continually challenged to adopt emerging clinical evidence into prac-
prostate cancer treatments may be affected by residual confounding. We tice. Management algorithms are one of the key clinical practice tools that
sought to quantify the degree of this bias in men treated for non–meta- can enable physicians to provide evidence–based and consensus–based
static prostate cancer, both between treatment modalities and compared care to patients with non–metastatic prostate cancer .
to men without prostate cancer.
Methods: We performed a population–based, retrospective cohort study MP–1.5
of men treated for non–metastatic prostate cancer in Ontario, Canada Efficacy and tolerability of first–line abiraterone + prednisone vs.
from 2002–2009. Patients treated with surgery and radiotherapy were enzalutamide for metastatic castration–resistant prostate cancer
matched on demographics, comorbidity, and cardiovascular risk factors. in men ≥80 years: A retrospective study
The primary outcome was non–prostate cancer mortality. The Fine & Daniel Khalaf , Kevin Zou , Werner Struss , Bernhard Eigl , Christian
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Gray subdistribution method with generalized estimating equations was Kollmannsberger , Daygen Finch , Krista Noonan , Joanna Vergidis ,
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used to compare outcomes. Additionally, we compared these patients Muhammad Zulfiqar , Kim Chi 1
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with prostate cancer to the general population. We used a previously 1 Department of Medical Oncology, BC Cancer Agency – Vancouver
published technique to quantify the prevalence and strength of residual Centre, Vancouver, BC, Canada; Faculty of Medicine, University of British
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confounding necessary to account for observed results. Columbia, Vancouver, BC, Canada; Department of Urology, University
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Results: Of 20 651 eligible men, 10 786 (5393 pairs) were matched. of British Columbia, Vancouver, BC, Canada; Department of Medical
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The 10–year cumulative incidence of non–prostate cancer mortality was Oncology , BC Cancer Agency – CSI, Kelowna, BC, Canada; Department
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higher among patients who underwent radiotherapy (12%) than surgery of Medical Oncology, BC Cancer Agency – Surrey, Surrey, BC, Canada;
(8%; adjusted subdistribution hazard ratio 1.57; 95% confidence inetrval 6 Department of Medical Oncology, BC Cancer Agency – Victoria, Victoria,
[CI] 1.35–1.83). Both groups had significantly lower rates of non–pros- BC, Canada; Department of Medical Oncology, BC Cancer Agency –
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tate cancer mortality than matched men without prostate cancer (18%; Abbotsford, Abbotsford, BC, Canada
p<0.001). Hypothetical residual confounders would have to be both Introduction: Abiraterone + prednisone (ABI) and enzalutamide (ENZA)
strongly associated with non–prostate cancer mortality (HRs in excess are both first–line treatment options for metastatic castration–resistant
of 2.5) and have highly differential prevalence in order to nullify the prostate cancer (mCRPC) with comparable efficacy. In men ≥75 years,
observed effect. ABI and ENZA are associated with higher rates of adverse events. For
Conclusions: Patients treated for non–metastatic prostate cancer have very elderly patients, the efficacy and tolerability of ABI and ENZA have
significantly lower non–prostate cancer mortality than men in the general not been directly compared.
population. We identified the magnitude of potential residual confounders Methods: We conducted a retrospective analysis in patients ≥80 years of
to account for differences in treatment effects for prostate cancer. age who received ABI or ENZA for first–line treatment of mCRPC between
July 2009 and September 2016 at the BC Cancer Agency. Medical records
MP–1.4 were reviewed for clinical characteristics and outcomes including pros-
Development of a management algorithm for prostate cancer tate–specific antigen (PSA) response rate (PSA50) (decrease of ≥50% from
patients with a biochemical recurrence after radical therapy baseline), time to first progression (TTP) (PSA [PCWG3 criteria], radio-
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Brita Danielson , Scott Morgan , Fred Saad , Robert Hamilton , Shawn graphic or clinical progression), and overall survival (OS).
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Malone , Anousheh Zardan , Laura Park–Wyllie , Bobby Shayegan 6 Results: There were 106 patients in the ABI cohort and 104 in the ENZA
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1 Cross Cancer Institute, University of Alberta, Edmonton, AB, Canada; cohort. Baseline age, Eastern Cooperative Oncology Group performance
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2 The Ottawa Hospital, University of Ottawa, Ottawa, ON, Canada; Centre score (ECOG PS), Charlson Comorbidity Index, serum alkaline phos-
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Hospitalier de l’Université de Montréal, Montreal, QC, Canada; Princess phatase (ALP) and lactate dehydrogenase (LDH), and sites of metastasis
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Margaret Hospital, University of Toronto, Toronto, ON, Canada; Medical were similar between cohorts, but a higher proportion of patients in the
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Affairs, Janssen Inc., Toronto, ON, Canada; Juravinski Cancer Centre & ENZA cohort had a time to castration resistance <12 months (Table 1;
St. Joseph’s Healthcare, McMaster University, Hamilton, ON, Canada available at https://cua.guide/). The PSA50was 43.4 % for ABI vs. 77.9 %

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Introduction: As new systemic treatments become available earlier in the for ENZA (p<0.001, Χ ). The median TTP was 4.7 months for ABI vs. 8.0
course of recurrent prostate cancer, it will become increasingly impor- months for ENZA (hazard ratio [HR] 1.52; 95% confidence interval [CI
tant for physicians to optimize the management of patients who develop ]1.12–2.08). Treatment was discontinued for toxicity in 8.5% of patients
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a biochemical recurrence post–radical local therapy. The Genitourinary for ABI and 13.5% for ENZA (p=0.276, Χ ). At least one dose reduction
Research Consortium (GURC) Best Practice Working Group identified due to toxicity was required for 7.5% of patients for ABI vs. 29.8% for
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a need to develop a monitoring and treatment algorithm to support the ENZA (p<0.001, Χ ). For patients in the ENZA cohort who had a dose
optimal management of patients with non–metastatic prostate cancer. reduction, the median TTP was 11.8 months vs. 6.2 months for those
Methods: A national working group of uro–oncologists, radiation oncolo- without (HR 0.65; 95% CI 0.40–1.08). Median OS was 13.2 months for
gists, and medical oncologists engaged in a series of best practice consen- ABI vs. 18.7 months for ENZA (HR 1.20; 95% CI 0.89–1.63).
sus discussions to examine the clinical trial evidence (literature review) Conclusions: Despite more dose reductions due to toxicity, the PSA50
and identify additional practice recommendations (expert opinion) that and TTP were superior for the ENZA cohort compared to the ABI cohort.
could be incorporated into an algorithm for the monitoring and treat- Dose reductions in the ENZA cohort did not negatively affect TTP. The
ment of patients with prostate cancer with a biochemical recurrence retrospective nature of the analysis is a limitation of this study.
post–radical local therapy.
Results: Multiple consensus meetings led to the integration of evidence
from randomized controlled trials and key retrospective studies, which
CUAJ • June 2018 • Volume 12(6Suppl2) S63