The role of the maximum involvement of biopsy core in predicting outcome for patients treated with dose-escalated radiation therapy for prostate cancer

Jure Murgic,Felix Y Feng,Daniel A Hamstra,Matthew H Stenmark,Kevin Blas,Schuyler Halverson

doi:10.1186/1748-717x-7-127

Abstract

PurposeTo evaluate the influence of the maximum involvement of biopsy core (MIBC) on outcome for prostate cancer patients treated with dose-escalated external beam radiotherapy (EBRT).Methods and materialsThe outcomes of 590 men with localized prostate cancer treated with EBRT (≥75 Gy) at a single institution were retrospectively analyzed. The influence of MIBC on freedom from biochemical failure (FFBF), freedom from metastasis (FFM), cause-specific survival (CSS), and overall survival (OS) was compared to other surrogates for biopsy tumor volume, including the percentage of positive biopsy cores (PPC) and the total percentage of cancer volume (PCV).ResultsMIBC correlated with PSA, T-stage, Gleason score, NCCN risk group, PPC, PCV, and treatment related factors. On univariate analysis, MIBC was prognostic for all endpoints except OS; with greatest impact in those with Gleason scores of 8–10. However, on multivariate analysis, MIBC was only prognostic for FFBF (hazard ratio [HR] 1.9, p = 0.008), but not for FFM (p = 0.19), CSS (p = 0.16), and OS (p = 0.99).ConclusionsIn patients undergoing dose-escalated EBRT, MIBC had the greatest influence in those with Gleason scores of 8–10 but provided no additional prognostic data as compared to PPC and PCV, which remain the preferable prognostic variables in this patient population.

Highlights

Pretreatment prognostic indices predictive of outcome in patients with clinically localized prostate cancer typically rely on risk-factors including: prostate-specific antigen (PSA), clinical T-stage, and biopsy Gleason score (GS) [1,2]
In a recent analysis we demonstrated that in a cohort of patients treated with dose-escalated external beam radiotherapy (EBRT), percentage of cancer volume (PCV) was superior to percentage of positive cores (PPC) as a prognostic variable for prediction of clinical outcomes
This study aimed to assess the prognostic significance of the maximum involvement of biopsy core by cancer (MIBC) as compared to both PPC and PCV in a cohort of patients treated with doseescalated EBRT for prostate cancer

Summary

Introduction

Pretreatment prognostic indices predictive of outcome in patients with clinically localized prostate cancer typically rely on risk-factors including: prostate-specific antigen (PSA), clinical T-stage, and biopsy Gleason score (GS) [1,2]. More recent models have evaluated the prognostic utility of incorporating biopsy tumor volume. Surrogates for cancer volume have included the percentage of positive cores (PPC) at the time of prostate biopsy [3,6] and the total percentage of cancer volume (PCV). The prognostic significance of the maximum involvement of biopsy core by cancer (MIBC) as compared to both PPC and PCV in a cohort of patients treated with doseescalated EBRT for prostate cancer

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