Intensity-modulated radiation therapy from 70Gy to 80Gy in prostate cancer: six- year outcomes and predictors of late toxicity

• Published in: Radiation oncology (London, England) England), 2017-06, Vol.12 (1), p.99-10, Article 99
• Main Authors: Jolnerovski, Maria, Salleron, Julia, Beckendorf, Véronique, Peiffert, Didier, Baumann, Anne-Sophie, Bernier, Valérie, Huger, Sandrine, Marchesi, Vincent, Chira, Ciprian
• Format: Article
• Language: English
• Subjects: Abdominal surgery; Adenocarcinoma - mortality; Adenocarcinoma - radiotherapy; Aged; Biochemistry; Bladder; Cancer; Cancer therapies; Care and treatment; Demographics; Demography; Deprivation; Dosimeters; Dosimetry; Humans; Intensity-modulated radiation therapy; Irradiation; Kaplan-Meier Estimate; Male; Medical prognosis; Metastasis; Methods; Middle Aged; Multivariate analysis; Patient outcomes; Prognostic factors; Proportional Hazards Models; Prostate cancer; Prostatic Neoplasms - mortality; Prostatic Neoplasms - radiotherapy; Quality; Radiation; Radiation Injuries - epidemiology; Radiation Injuries - etiology; Radiation therapy; Radiotherapy; Radiotherapy Dosage; Radiotherapy, Intensity-Modulated - adverse effects; Radiotherapy, Intensity-Modulated - methods; Rectal and urinary toxicity; Rectum; Rectum - radiation effects; Regression analysis; Retrospective Studies; Risk; Risk groups; Statistical methods; Survival; Terminology; Toxicity; Urinary bladder; Urinary Bladder - radiation effects
• ISSN: 1748-717X; 1748-717X
• DOI: 10.1186/s13014-017-0839-3

To report grade ≥2 overall late rectal and urinary toxicities in patients (pts) with prostate cancer treated by intensity-modulated radiotherapy (IMRT) at 3 dose-levels. Identify predictors of radiation toxicity and report biochemical progression free survival (bPFS). A total of 277 pts were treated with 70Gy (10.8%), 74Gy (63.9%) and 80 Gy (25.3%) using IMRT without pelvic irradiation were analyzed. Short or long-course androgen deprivation therapy (ADT) was allowed in 46.1% of pts. The toxicity was described using the Common Terminology Criteria for Adverse Events (CTCAE) v4.0 scale. Cox regression models addressed demographics, disease and dosimetry characteristics as potential predictors of late grade ≥2 toxicity after adjusting for other modifying factors. The median follow-up was 77 months (range 15; 150). There was no grade ≥4 toxicity. The 5-year cumulative rate of grade ≥2 late rectal and urinary toxicities was 6.3% (95% CI = 3.8%; 10.3%) and 25.3% (95% CI = 19.8%; 31.8%) respectively. In multivariate analysis, only the dose (80Gy vs 74 and 70Gy) was found to increase the risk of rectal toxicity (HR = 2.96 [1.07; 8.20]). For pts receiving 74 Gy, International Prostate Symptom Score (IPSS) at baseline ≥8 (HR = 2.40 [1.08; 5.35]) and dose ≥73Gy delivered in more than 2% of bladder (D2%) were found to be predictors of bladder toxicity (HR = 3.29 [1.36; 7.98]). The 5-year biochemical relapse free survival was 81.0% [74.5%; 86.0%] in the entire population, 97.5% [83.5%; 99.6%] in the low risk group, 84.9% [76.7%; 90.3%] in the intermediate risk group and 66.4% [51.8%; 77.4%] in the high-risk group. D'Amico low (HR = 0.09 [0.01; 0.69]) and intermediate risk groups (HR = 0.50 [0.28; 0.88]) as well as PSA nadir ≥0.2 ng/ml (HR = 1.79 [1.01; 3.21]) were predictive of biochemical relapse. The rate of late rectal toxicity increased with higher doses, while Dmax ≥74Gy, D2% ≥ 73Gy for bladder wall and baseline IPSS ≥8 increased late urinary toxicity.