Clinical and Dosimetric Predictors of Acute Toxicity After a 4-Week Hypofractionated External Beam Radiotherapy Regimen for Prostate Cancer: Results From a Multicentric Prospective Trial
Received 6 February 2008; received in revised form 1 April 2008; accepted 7 April 2008. published online 05 June 2008.
Purpose
To investigate predictors for gastrointestinal (GI) and genitourinary (GU) acute toxicity after a short-course hypofractionated radiotherapy regimen for prostate cancer.
Materials and Methods
Three institutions included 102 patients with T1-T3N0M0 prostate cancer in a Phase II study. Patients were treated with 56 Gy in 16 fractions over 4 weeks. Acute toxicity was scored weekly during treatment and 1 and 2 months after treatment using the Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer criteria extended with additional symptoms and the International Prostate Symptom Index (IPSS). Correlation with a number of clinical and dosimetric parameters was assessed by univariate and multivariate analyses.
Results
No Grade 3 or 4 GI side effects were observed. Grades 1 and 2 rectal GI toxicity occurred in 36%, and 38%, respectively. Corresponding figures for Grades 1 and 2 GU toxicity were 42% and 39%, respectively. Grade 3 or higher GU toxicity was detected in 4% of patients. In multivariate analysis, percent rectal volumes higher than 8% receiving doses ≥53 Gy (V53) were statistically correlated to Grade 2 acute rectal reaction (p = 0.006). For GU morbidity, only the IPSS pretreatment score was independently associated (p = 0.0036) with an increase in GU acute effects.
Conclusions
Acute GU and GI toxicity were comparable with other series. Our data show that increased incidence and intensity of acute toxicity is a transient effect related to shorter overall treatment time rather than a larger effect in biological equivalent dose with respect to a conventional fractionation regime.
∗Departments of Radiotherapy, Regina Elena National Cancer Institute, Rome, Italy
†Laboratory of Medical Physics and Expert Systems, Regina Elena National Cancer Institute, Rome, Italy
‡Department of Radiotherapy Oncology Center, Universitair Ziekenhuis Brussels, Jette, Belgium
§Department of Radiotherapy, Ghent University Hospital, Ghent, Belgium
Reprint requests to: Stefano Arcangeli, M.D., Department of Radiotherapy, Regina Elena National Cancer Institute, via Elio Chianesi, 53, 00144 Rome, Italy. Tel: (+39) 06-52663028; Fax: (+39) 06-52665667
ABSTRACT