Abstract
Purpose
To investigate if stereotactic ablative radiotherapy (SABR) dose is associated with
PSA at 3 years (PSA3y) in the treatment of localized prostate cancer and to explore predictors of late
genitourinary (GU) toxicity.
Materials and methods
Three prospective trials of SABR were undertaken at our institution: 1) 35 Gy/5 fractions/29 days; 2) 40 Gy/5 fractions/29 days; 3) 40 Gy/5 fractions/11 or 29 days. PSA3y was analyzed as a continuous variable. Toxicity was defined as the worst new toxicity
and assessed using the radiation therapy oncology group (RTOG) late morbidity scheme.
Univariate and multivariable regression analyses were conducted to assess the association
between dose and PSA3y, and to explore predictors of late grade 2+ GU toxicity.
Results
Median PSA3y was 0.64 (intraquartile range (IQR): 0.41–1.12) and 0.27 (IQR: 0.12–0.55)
ng/mL for patients treated with 35 and 40 Gy respectively. A dose of 40 Gy was an independent predictor of lower PSA3y on multivariable analysis (p < 0.001). Dose of 40 Gy (odds ratio (OR): 16.69, 95%CI: 5.78, 48.20, p < 0.001) and higher International Prostate Symptom Score (OR: 1.01, 95%CI: 1.04, 1.16,
p = 0.001) predicted for late grade 2+ GU toxicity on multivariable logistic regression.
Conclusions
This analysis suggests that higher SABR dose is associated with lower PSA3y. Strategies to allow safe SABR dose escalation should be further investigated.
Keywords
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Article info
Publication history
Published online: April 19, 2017
Accepted:
March 11,
2017
Received in revised form:
March 9,
2017
Received:
October 5,
2016
Identification
Copyright
© 2017 Elsevier B.V. All rights reserved.
