title: Small bowel toxicity in pelvic radiotherapy for postoperative gynecological cancer: comparison between conformal radiotherapy and intensity modulated radiotherapy.
abstract: OBJECTIVE
  To compare the dosimetric advantages of pelvic intensity modulated radiotherapy (IMRT) with three-dimensional conformal radiotherapy (3D CRT) in small bowel dose reduction and dosimetrically correlate the clinical benefit, if any.
  
  
  METHODS
  This retrospective study included 60 patients with gynecological cancers treated postoperatively with radiotherapy to the whole pelvis. Radiation Therapy Oncology Group (RTOG) contouring guidelines were used for contouring the pelvic nodal stations. All plans were generated using Plato Sunrise treatment planning system. The RTOG acute morbidity scoring criteria were used to define acute small bowel toxicity in our patients. Treatment was delivered using the Elekta Precise system. Patients were followed up twice weekly while on treatment. Statistical analyses (Spearman's rho and Kruskal-Wallis test) were performed using SPSS software (vers. 15).
  
  
  RESULTS
  In all, 65% were postoperative endometrium carcinoma and 35% were postoperative cervix carcinoma patients; 34 patients were treated with IMRT and 26 patients underwent 3D CRT. In all, 28 patients experienced ≥ grade 2 small bowel toxicity (eight in the IMRT group). IMRT was able to significantly reduce the dose to bowel for doses above 30 Gy. Small bowel toxicity showed no correlation with doses below 30 Gy. The volume of the small bowel receiving more than 35 Gy of radiation was a significant predictor of the need for medication to control diarrhea during radiotherapy.
  
  
  CONCLUSIONS
  Use of IMRT resulted in lower doses to the small bowel, resulting in lesser toxicity, and translated to the better tolerability of pelvic radiotherapy.
authors.affiliation: Radiotherapy Department, Nilratan Sircar Medical College Medical College, Kolkata, India. dramitabhray@gmail.com
authors.forename: Amitabh
authors.initials: A
authors.lastname: Ray
authors.forename: Biplab
authors.initials: B
authors.lastname: Sarkar
mesh_terms: D016889:Endometrial Neoplasms / Q000532:radiotherapy*; D005260:Female; D006801:Humans; D007410:Intestinal Diseases / Q000209:etiology*; D007421:Intestine, Small / Q000528:radiation effects*; D008875:Middle Aged; D011832:Radiation Injuries / Q000209:etiology*; D020266:Radiotherapy, Conformal / Q000009:adverse effects; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects; D012189:Retrospective Studies; D002583:Uterine Cervical Neoplasms / Q000532:radiotherapy*
keywords: IMRT; bowel toxicity; pelvic radiotherapy