1. Predicting the 5-Year Risk of Biochemical Relapse After Postprostatectomy Radiation Therapy in ≥PT2, pN0 Patients With a Comprehensive Tumor Control Probability Model.
- Author
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Fiorino C, Broggi S, Fossati N, Cozzarini C, Goldner G, Wiegel T, Hinkelbein W, Karnes RJ, Boorjian SA, Haustermans K, Joniau S, Palorini F, Shariat S, Montorsi F, Van Poppel H, Di Muzio N, Calandrino R, and Briganti A
- Subjects
- Adult, Aged, Biomarkers, Tumor blood, Disease-Free Survival, Female, Humans, Italy epidemiology, Longitudinal Studies, Male, Middle Aged, Neoplasm Recurrence, Local blood, Neoplasm Staging, Prevalence, Prognosis, Proportional Hazards Models, Prostatectomy, Prostatic Neoplasms blood, Radiotherapy, Adjuvant, Radiotherapy, Conformal, Reproducibility of Results, Risk Assessment methods, Sensitivity and Specificity, Models, Statistical, Neoplasm Recurrence, Local epidemiology, Neoplasm Recurrence, Local prevention & control, Prostate-Specific Antigen blood, Prostatic Neoplasms epidemiology, Prostatic Neoplasms therapy
- Abstract
Purpose: To fit the individual biochemical recurrence-free survival (bRFS) data from patients treated with postprostatectomy radiation therapy (RT) with a comprehensive tumor control probability (TCP) model., Methods and Materials: Considering pre-RT prostate-specific antigen (PSA) as a surrogate of the number of clonogens, bRFS may be expressed as a function of dose-per-fraction-dependent radiosensitivity (αeff), the number of clonogens for pre-RT PSA = 1 ng/mL (C), and the fraction of patients who relapse because of clonogens outside the treated volume (K), assumed to depend (linearly or exponentially) on pre-RT PSA and Gleason score (GS). Data from 894 node-negative, ≥pT2, pN0 hormone-naive patients treated with adjuvant (n=331) or salvage (n=563) intent were available: 5-year bRFS data were fitted grouping patients according to GS (<7:392, =7:383, >7:119)., Results: The median follow-up time, pre-RT PSA, and dose were 72 months, 0.25 ng/mL, and 66.6 Gy (range 59.4-77.4 Gy), respectively. The best-fit values were 0.23 to 0.26 Gy(-1) and 10(7) for αeff and C for the model considering a linear dependence between K and PSA. Calibration plots showed good agreement between expected and observed incidences (slope: 0.90-0.93) and moderately high discriminative power (area under the curve [AUC]: 0.68-0.69). Cross-validation showed satisfactory results (average AUCs in the training/validation groups: 0.66-0.70). The resulting dose-effect curves strongly depend on pre-RT PSA and GS. bRFS rapidly decreases with PSA: the maximum obtainable bRFS (defined as 95% of the maximum) declined by about 2.7% and 4.5% for each increment of 0.1 ng/mL for GS <7 and ≥7, respectively., Conclusions: Individual data were fitted by a TCP model, and the resulting best-fit parameters were radiobiologically consistent. The model suggests that relapses frequently result from clonogens outside the irradiated volume, supporting the choice of lymph-node irradiation, systemic therapy, or both for specific subgroups (GS <7: PSA >0.8-1.0 ng/mL; GS ≥7: PSA >0.3 ng/mL). Early RT should be preferred over delayed RT; the detrimental effect of PSA increase can never be fully compensated by increasing the dose, especially for patients with GS ≥7., (Copyright © 2016 Elsevier Inc. All rights reserved.)
- Published
- 2016
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