1136: Which Definition of Biochemical Failure after Post-Operative Radiotherapy Predicts Best for Clinical Failure? A Multi-Institutional Analysis

80 Background: To assess the prognostic value of percentage of positive biopsy cores (PPC) and perineural invasion (PNI) in predicting clinical outcome following radiotherapy (RT) for prostate cancer. Methods: One thousand and fifty-six patients with clinical stage T1-T3 N0 M0 prostate cancer, who had ≥ 4 biopsy cores sampled and complete biopsy core data available, were treated with either adaptive image-guided RT (median 75.6 Gy, n=387), low-dose EBRT (median 66.6 Gy, n=393), or EBRT and high-dose rate brachytherapy boost (n=276) at William Beaumont Hospital (1993-2004). Neoadjuvant and/or adjuvant androgen deprivation (AD) were given to 253 patients (24%). Multivariate cox regression analysis included PPC, gleason score, PSA, T stage, PNI, RT dose, androgen deprivation, and age. Biochemical failure (BF) was scored according to the Phoenix definition. Clinical failure (CF) was defined as any locoregional recurrence (LRR) or distant metastasis (DM). Median follow-up was 7.6 years. Results: Median cores sampled was 7, median PPC was 33%, and 18% had PNI. On univariate Cox regression, both PPC and PNI were predicators of biochemical failure and clinical failure (all P<0.05). On multivariate Cox regression, PPC, either as continuous or categorical variable, remained an independent predicator of BF, CF, DM, cause-specific survival, and overall survival (all P<0.05). PPC of >50% was associated with significantly higher DM (HR 4.01, 95% CI 1.86-8.61), and its independent predicative value remained significant whether AD was given or not (all P<0.05). Combining ≤50% vs ≥50% PPC with NCCN risk group stratification demonstrated added prognostic value of DM for intermediate-risk (HR 5.44, 95% CI 1.78-16.6) and high-risk groups (HR 4.39, 95% CI 1.70-2.84), with or without AD (all P<0.05). On multivariate Cox regression, PNI was an independent predicator of LRR only (HR 2.51, 95% CI 1.18-5.33). Conclusions: PPC is an independent and powerful predicator of DM for intermediate- and high-risk prostate cancer, regardless the use of AD. It should be considered for risk stratification and when designing for future trials testing adjuvant treatment after definitive RT for prostate cancer. No significant financial relationships to disclose.

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Impact of timing of biochemical failure on the eventual development of clinical failure after definitive treatment with brachytherapy or external beam radiotherapy for prostate cancer.

Journal of Clinical Oncology ◽

10.1200/jco.2015.33.7_suppl.53 ◽

2015 ◽

Vol 33 (7_suppl) ◽

pp. 53-53

Author(s):

Jay P. Ciezki ◽

Chandana A. Reddy ◽

Eric A. Klein ◽

James Ulchaker ◽

Kenneth Angermeier ◽

...

Keyword(s):

Prostate Cancer ◽

External Beam Radiotherapy ◽

Biochemical Failure ◽

Definitive Treatment ◽

External Beam ◽

Clinical Failure ◽

Psa Testing ◽

Testing Frequency ◽

Definitive Therapy

53 Background: Late treatment failure is often considered to be a rare event. We will assess the influence of the timing of biochemical failure (bF) after definitive brachytherapy (BT) or external beam radiotherapy (EBRT) for prostate cancer on its frequency and association with clinical failure (cF). Methods: Patients with prostate cancer treated between 1996 and 2009 with at least 5 years of follow-up (N= 2,293; 1,060 EBRT, 1,233 BT) were studied in the context of an IRB-approved inception cohort study. Those with a bF were reviewed to determine the timing of bF [< 5 years after treatment (bF<5) vs. > 5 years after treatment (bF>5)] and occurrence of cF post-bF. The bF definition used was the nadir + 2.0 ng/mL version. Results: Of the total patient population, 477 (21%) were noted to have bF- 244 (11%) bF<5 vs. 233 (10%) bF>5. The median follow-up after bF for the bF< 5 group is 41 months while in the bF> 5 group it is 22 months. In the BT group, 94 (8%) failed < 5 years and 87 (7%) failed > 5 years. In the EBRT group, 150 (14%) failed < 5 years and 146 (14%) failed > 5 years. The median PSA value (ng/mL) at the time of bF for all patients, EBRT, and BT in the bF<5 group was 3.70, 3.65, and 3.80, respectively (p=not significant). The median PSA value (ng/mL) at the time of bF for all patients, EBRT, and BT in the bF>5 group was 3.01, 3.01, and 3.04, respectively (p=not significant). Overall, 53.3% of patients in the bF<5 group developed cF while 27% of patients in the bF>5 group developed a cF. The actuarial five year rate of cF for the bF <5 group was 50% vs. 38% for the bF>5 group (p= 0.028). The detection of bF and cF was closely linked to PSA testing frequency ( p < 0.0001). Conclusions: The risk of bF does not appear to decrease >5 years post treatment. Late bF (i.e. >5 years after treatment) may still result in eventual cF. While cF is less common after bF > 5 years post definitive therapy, it still affects 27% of those with bF and is strongly associated with PSA testing frequency. The lower rate of cF after 5 years may relate to the shorter follow-up time for this group.

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Coasean method: lessons from the farm

Journal of Institutional Economics ◽

10.1017/s1744137414000320 ◽

2014 ◽

Vol 11 (1) ◽

pp. 93-110 ◽

Cited By ~ 2

Author(s):

DOUGLAS W. ALLEN

Keyword(s):

Transaction Costs ◽

Hypothesis Testing ◽

Subject Matter ◽

Institutional Analysis ◽

Level Of Detail ◽

Transaction Level ◽

The Rich ◽

Definition Of ◽

Farm Economics

AbstractRonald Coase detested ‘blackboard economics’ and as a result was often criticized for being ‘against theory’. Coase has also been criticized for being overly descriptive in his institutional analysis. Here, I claim that Coase was both theoretical and interested in hypothesis testing. In order to do Coasean analysis, however, it is necessary to analyse a subject matter at the deep transaction level, given the definition of transaction costs. The rich level of detail required may give the impression of an absence of theory or testing. Here, I provide a number of real farm examples and contrast them with blackboard farm economics to make this point.

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