title: Acute toxicity with intensity modulated radiotherapy versus 3-dimensional conformal radiotherapy during preoperative chemoradiation for locally advanced rectal cancer.
abstract: We examined acute toxicity profiles and outcomes among rectal cancer patients treated with pre-operative chemoradiation using intensity modulated radiotherapy (IMRT) or 3-dimensional conformal radiotherapy (3DCRT) to identify predictive clinical factors associated with increased acute toxicity.
  
  
  
  We retrospectively reviewed records of 301 consecutive rectal cancer patients treated with pre-operative chemotherapy and radiotherapy (median dose 5000cGy) at our institution between 2007 and 2014.
  
  
  
  Of the 301 patients, 203 (67.4%) were treated with IMRT and 98 (32.6%) with 3DCRT. Significantly more patients experienced ⩾grade 2 diarrhea in the 3DCRT group compared to the IMRT group (22% vs 10%, p=0.004), and those who received 3DCRT had 2.7 times greater odds of a higher diarrhea score than those on IMRT, even after adjusting for patient characteristics and chemotherapy (OR 2.71, p=0.01) Fewer patients experienced grade 2 genitourinary toxicity in the IMRT group (6% vs 13% 3DCRT, p=0.04) and there was a trend toward decreased grade 2 proctitis in the IMRT group (22% vs 32% 3DCRT, p=0.07). Patients over the age of 55 had 45% lower odds of proctitis than patients younger than 55.
  
  
  
  The use of IMRT significantly reduced grade ⩾2 diarrhea and GU toxicity during chemoradiation. Younger patients were more likely to report grade 2 or higher proctitis.
authors.affiliation: Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, USA.
authors.forename: Shu Y
authors.initials: SY
authors.lastname: Ng
authors.affiliation: Division of Health Care Policy and Research, Adult and Child Consortium for Health Outcomes Research and Delivery Science, University of Colorado Denver School of Medicine, USA.
authors.forename: Kathryn L
authors.initials: KL
authors.lastname: Colborn
authors.affiliation: Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, USA.
authors.forename: Lajhem
authors.initials: L
authors.lastname: Cambridge
authors.affiliation: Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, USA.
authors.forename: Carla
authors.initials: C
authors.lastname: Hajj
authors.affiliation: Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, USA.
authors.forename: T Jonathan
authors.initials: TJ
authors.lastname: Yang
authors.affiliation: Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, USA.
authors.forename: Abraham J
authors.initials: AJ
authors.lastname: Wu
authors.affiliation: Department of Radiation Oncology, University of Colorado Denver School of Medicine, USA. Electronic address: karyn.goodman@ucdenver.edu.
authors.forename: Karyn A
authors.initials: KA
authors.lastname: Goodman
mesh_terms: D000208:Acute Disease; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D059186:Chemoradiotherapy, Adjuvant / Q000009:adverse effects / Q000379:methods; D003967:Diarrhea / Q000209:etiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011349:Proctitis / Q000209:etiology; D011832:Radiation Injuries / Q000209:etiology; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal / Q000009:adverse effects* / Q000379:methods; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects* / Q000379:methods; D012004:Rectal Neoplasms / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D012189:Retrospective Studies; D012307:Risk Factors; D014566:Urogenital System / Q000528:radiation effects; D055815:Young Adult
keywords: Intensity modulated radiotherapy; Locally advanced rectal cancer; Pelvic radiotherapy; Pre-operative chemoradiation; Toxicity