title: Reduced radiation tolerance of penile structures associated with dose-escalated hypofractionated prostate radiotherapy.
abstract: OBJECTIVE
  To investigate the effect of hypofractionated external beam radiation therapy (RT) on sexual function in patients treated for localized prostate cancer, and also to determine the effect of radiation dose to the penile bulb or crura of the corpus cavernosum on sexual function outcome.
  
  
  METHODS
  Forty-one patients treated with hypofractionated RT without androgen deprivation were prescribed 67.6-70.2 Gy to the prostate, delivered in 26-28 fractions. The primary endpoint was erectile dysfunction (ED) category based on the Sexual Health Inventory for Men (SHIM) score closest to 2 years from RT. The penile bulb and crura were contoured and mean radiation dose calculated for each structure.
  
  
  RESULTS
  The mean pretreatment SHIM score was 19.8, and the mean posttreatment SHIM score was 15.1. The ED category was decreased by ≥ 2 in 50% of patients with a mean penile bulb of >20 Gy compared with that in 9% of patients with a mean penile bulb dose of ≤ 20 Gy (P = .003). Mean dose to the crura was highly correlated with mean dose to the penile bulb (Pearson correlation = 0.842; P <.001) but did not reach statistical significance as a predictor of ED after radiation.
  
  
  CONCLUSIONS
  Radiation dose to the penile bulb is predictive of posttreatment ED in patients treated with dose-escalated hypofractionated prostate RT. The cutpoint at which this effect was observed with this treatment is substantially lower than the previous reports.
authors.affiliation: Department of Radiation Oncology, University of Alabama at Birmingham, Birmingham, AL. Electronic address: ammcdonald@uabmc.edu.
authors.forename: Andrew M
authors.initials: AM
authors.lastname: McDonald
authors.affiliation: University of Alabama School of Medicine, Birmingham, AL.
authors.forename: Christopher B
authors.initials: CB
authors.lastname: Baker
authors.affiliation: University of Alabama at Birmingham Center for Clinical and Translational Science, Birmingham, AL.
authors.forename: Kiran
authors.initials: K
authors.lastname: Shekar
authors.affiliation: Department of Radiation Oncology, University of Alabama at Birmingham, Birmingham, AL.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Popple
authors.affiliation: Department of Radiation Oncology, University of Alabama at Birmingham, Birmingham, AL.
authors.forename: Grant M
authors.initials: GM
authors.lastname: Clark
authors.affiliation: Department of Radiation Oncology, University of Alabama at Birmingham, Birmingham, AL.
authors.forename: Eddy S
authors.initials: ES
authors.lastname: Yang
authors.affiliation: Department of Radiation Oncology, University of Alabama at Birmingham, Birmingham, AL.
authors.forename: Rojymon
authors.initials: R
authors.lastname: Jacob
authors.affiliation: Department of Radiation Oncology, University of Alabama at Birmingham, Birmingham, AL.
authors.forename: Robert Y
authors.initials: RY
authors.lastname: Kim
authors.affiliation: Department of Radiation Oncology, University of Alabama at Birmingham, Birmingham, AL.
authors.forename: John B
authors.initials: JB
authors.lastname: Fiveash
mesh_terms: D000368:Aged; D015331:Cohort Studies; D019583:Dose Fractionation, Radiation; D004307:Dose-Response Relationship, Radiation; D007172:Erectile Dysfunction / Q000209:etiology* / Q000503:physiopathology; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D010413:Penis / Q000528:radiation effects*; D011471:Prostatic Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal / Q000009:adverse effects* / Q000379:methods; D012189:Retrospective Studies; D018570:Risk Assessment; D016896:Treatment Outcome