title: Degree of Rectal Distension Seen on Prostate Radiotherapy Planning CT Scan Is Not a Negative Prognostic Factor in the Modern Era of Image-Guided Radiotherapy.
abstract: BACKGROUND
  Studies have shown that rectal distension has a significant impact on treatment failure in patients receiving radical radiotherapy for prostate cancer. A distended rectum contributes to excessive organ movement during treatment, resulting in significant underdosing of the target volume and higher treatment failure rates. The increasing use of highly conformal, precise radiotherapy techniques places greater importance on reducing this risk. We tested whether imaging during radiotherapy helps minimise the negative impact that rectal distension has on long-term tumour control.
  
  
  RESULTS
  The rectal diameter (anterior/posterior and lateral) was prospectively measured at radiotherapy planning in 172 consecutive patients undergoing radical radiotherapy with three-dimensional conformal radiotherapy. Daily, and then weekly, imaging during radiotherapy ensured that prostate movement remained within predefined tolerances. Patients were followed up for a median of 72 months with regular prostate-specific antigen (PSA) measurements to ascertain biochemical PSA relapse and survival information.
  
  
  CONCLUSIONS
  In this cohort of predominately high-risk localised prostate cancer, rectal distension had no significant impact on PSA relapse. We suggest that regular imaging during radiotherapy negates the risk caused by rectal distension on local treatment failure.
authors.affiliation: Department of Oncology, Nottingham City Hospital, Nottingham University Hospitals, Nottingham, UK.
authors.forename: Rafael
authors.initials: R
authors.lastname: Silverman
authors.forename: Kerstie
authors.initials: K
authors.lastname: Johnson
authors.forename: Christina
authors.initials: C
authors.lastname: Perry
authors.forename: Santhanam
authors.initials: S
authors.lastname: Sundar
mesh_terms: D000368:Aged; D014408:Biomarkers, Tumor / Q000097:blood; D004108:Dilatation, Pathologic / Q000000981:diagnostic imaging; D018450:Disease Progression; D018572:Disease-Free Survival; D005500:Follow-Up Studies; D006801:Humans; D021621:Imaging, Three-Dimensional; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000097:blood; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000097:blood / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D011881:Radiotherapy, Computer-Assisted; D020266:Radiotherapy, Conformal / Q000379:methods*; D061089:Radiotherapy, Image-Guided; D012007:Rectum / Q000000981:diagnostic imaging / Q000473:pathology*; D012307:Risk Factors; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D017211:Treatment Failure
chemical_list: D014408:Biomarkers, Tumor; D017430:Prostate-Specific Antigen