title: High-dose-rate intraoperative radiotherapy for close or positive margins in patients with locally advanced or recurrent rectal cancer.
abstract: OBJECTIVE
  A high-dose-rate intraoperative radiotherapy (HDR-IORT) technique for rectum cancer was developed and the technique, local failure, and survival were analyzed.
  
  
  METHODS
  After the exclusion of metastatic patients, 37 patients were treated with external beam RT, surgery, and HDR-IORT between 1997 and 2000. Primary locally advanced rectum cancer was found in 18 patients and recurrent disease in 19. HDR-IORT was only administered if the resection margins were < or =2 mm. The flexible intraoperative template is a 5-mm-thick pad with 1-cm-spaced parallel catheters. Clips were placed during surgery to define the target area. A dose of 10 Gy was prescribed at a 1 cm depth from the template surface and calculated using standard plans. After treatment, the dose at the clips was calculated using the reconstructed template geometry and the actual treatment dwell times. The median follow-up of surviving patients was 3 years. No patients were lost to follow-up.
  
  
  RESULTS
  Overall, 12 patients (32%) had local recurrence, 5 (14%) of which were in the HDR-IORT field. The 3-year local failure rate for primary tumors and recurrent tumors was 19% and 52%, respectively (p = 0.0042). The 3-year local failure rate was 37% for negative margins and 26% for positive margins (p = 0.51). A high mean dose at the clip (17.3 Gy) was found. The overall survival was significantly different for primary vs. recurrent tumors, stage, and grade.
  
  
  CONCLUSIONS
  Because of the HDR technique, a high dose at the clips was found, with good local control. More out-of-field than in-field failures were seen. The local failure rate was significantly different for primary vs. recurrent disease.
authors.affiliation: Department of Radiation Oncology, Erasmus Medical Center-Daniel Den Hoed, Rotterdam, The Netherlands. j.nuyttens@erasmusmc.nl
authors.forename: Joost J
authors.initials: JJ
authors.lastname: Nuyttens
authors.forename: Inger-Karine K
authors.initials: IK
authors.lastname: Kolkman-Deurloo
authors.forename: Maarten
authors.initials: M
authors.lastname: Vermaas
authors.forename: Floris T
authors.initials: FT
authors.lastname: Ferenschild
authors.forename: Wilfried J
authors.initials: WJ
authors.lastname: Graveland
authors.forename: Johannes H
authors.initials: JH
authors.lastname: De Wilt
authors.forename: Patrick E
authors.initials: PE
authors.lastname: Hanssens
authors.forename: Peter C
authors.initials: PC
authors.lastname: Levendag
mesh_terms: D000328:Adult; D000368:Aged; D003131:Combined Modality Therapy; D005260:Female; D006801:Humans; D007432:Intraoperative Period; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D011878:Radiotherapy / Q000009:adverse effects; D011879:Radiotherapy Dosage; D012004:Rectal Neoplasms / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D016019:Survival Analysis