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.
OBJECTIVE
To investigate predictors for gastrointestinal (GI) and genitourinary (GU) acute toxicity after a short-course hypofractionated radiotherapy regimen for prostate cancer.


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 (V(53)) 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.
Stefano
S
Arcangeli
Lidia
L
Strigari
Guy
G
Soete
Gert
G
De Meerleer
Sara
S
Gomellini
Valerie
V
Fonteyne
Guy
G
Storme
Giorgio
G
Arcangeli
D000368:Aged; D000369:Aged, 80 and over; D001530:Belgium; D019583:Dose Fractionation, Radiation; D004307:Dose-Response Relationship, Radiation; D005767:Gastrointestinal Diseases / Q000175:diagnosis* / Q000209:etiology*; D006801:Humans; D007558:Italy; D008297:Male; D008875:Middle Aged; D011471:Prostatic Neoplasms / Q000150:complications* / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000175:diagnosis / Q000209:etiology*; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal / Q000009:adverse effects*; D018570:Risk Assessment / Q000379:methods; D012307:Risk Factors; D016896:Treatment Outcome