The impact of pretreatment prostate volume on severe acute genitourinary toxicity in prostate cancer patients treated with intensity-modulated radiation therapy.
OBJECTIVE
To assess the impact of pretreatment prostate volume on the development of severe acute genitourinary toxicity in patients undergoing intensity-modulated radiation therapy (IMRT) for prostate cancer.


METHODS
Between 2004 and 2007, a consecutive sample of 214 patients who underwent IMRT (75.6 Gy) for prostate cancer at two referral centers was analyzed. Prostate volumes were obtained from computed tomography scans taken during treatment simulation. Genitourinary toxicity was defined using the National Cancer Institute Common Terminology Criteria for Adverse Events Version 3.0 guidelines. Acute toxicity was defined as any toxicity originating within 90 days of the completion of radiation therapy. Patients were characterized as having a small or large prostate depending on whether their prostate volume was less than or greater than 50 cm(3), respectively. Genitourinary toxicity was compared in these groups using the chi-square or Fisher's exact test, as appropriate. Bivariate and multivariate logistic regression analysis was performed to further assess the impact of prostate volume on severe (Grade 3) acute genitourinary toxicity.


RESULTS
Patients with large prostates (>50 cm(3)) had a higher rate of acute Grade 3 genitourinary toxicity (p = .02). Prostate volume was predictive of the likelihood of developing acute Grade 3 genitourinary toxicity on bivariate (p = .004) and multivariate (p = .006) logistic regression. Every 27.0 cm(3) increase in prostate volume doubled the likelihood of acute Grade 3 genitourinary toxicity.


CONCLUSIONS
Patients with larger prostates are at higher risk for the development of severe acute genitourinary toxicity when treated with IMRT for prostate cancer.
Aizer
Ayal A
AA
Department of Therapeutic Radiology, Yale School of Medicine, New Haven, CT, USA. Ayal.Aizer@yale.edu
Anderson
Nicole S
NS
Oh
Steven C
SC
Yu
James B
JB
McKeon
Anne M
AM
Decker
Roy H
RH
Peschel
Richard E
RE
D000368:Aged; D000726:Androgen Antagonists / Q000627:therapeutic use; D016009:Chi-Square Distribution; D006801:Humans; D008297:Male; D009929:Organ Size; D010146:Pain / Q000209:etiology; D011467:Prostate / Q000473:pathology*; D011471:Prostatic Neoplasms / Q000188:drug therapy / Q000473:pathology* / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000150:complications; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects* / Q000379:methods; D012007:Rectum / Q000528:radiation effects; D012044:Regression Analysis; D012189:Retrospective Studies; D047368:Tumor Burden; D014522:Urethral Diseases / Q000209:etiology; D014555:Urination Disorders / Q000209:etiology; D014566:Urogenital System / Q000528:radiation effects*
D000726:Androgen Antagonists