title: Intraoperative radiation therapy reduces local recurrence rates in patients with microscopically involved circumferential resection margins after resection of locally advanced rectal cancer.
abstract: OBJECTIVE
  Intraoperative radiation therapy (IORT) is advocated by some for patients with locally advanced rectal cancer (LARC) who have involved or narrow circumferential resection margins (CRM) after rectal surgery. This study evaluates the potentially beneficial effect of IORT on local control.
  
  
  METHODS
  All surgically treated patients with LARC treated in a tertiary referral center between 1996 and 2012 were analyzed retrospectively. The outcome in patients treated with IORT with a clear but narrow CRM (≤2 mm) or a microscopically involved CRM was compared with the outcome in patients who were not treated with IORT.
  
  
  RESULTS
  A total of 409 patients underwent resection of LARC, and 95 patients (23%) had a CRM ≤ 2 mm. Four patients were excluded from further analysis because of a macroscopically involved resection margin. In 43 patients with clear but narrow CRMs, there was no difference in the cumulative 5-year local recurrence-free survival of patients treated with (n=21) or without (n=22) IORT (70% vs 79%, P=.63). In 48 patients with a microscopically involved CRM, there was a significant difference in the cumulative 5-year local recurrence-free survival in favor of the patients treated with IORT (n=31) compared with patients treated without IORT (n=17) (84 vs 41%, P=.01). Multivariable analysis confirmed that IORT was independently associated with a decreased local recurrence rate (hazard ratio 0.24, 95% confidence interval 0.07-0.86). There was no significant difference in complication rate of patients treated with or without IORT (65% vs 52%, P=.18) CONCLUSION: The current study suggests that IORT reduces local recurrence rates in patients with LARC with a microscopically involved CRM.
authors.affiliation: Department of Surgery, Division of Surgical Oncology, Erasmus MC Cancer Institute, Rotterdam, the Netherlands.
authors.forename: Wijnand J
authors.initials: WJ
authors.lastname: Alberda
authors.affiliation: Department of Surgery, Division of Surgical Oncology, Erasmus MC Cancer Institute, Rotterdam, the Netherlands.
authors.forename: Cornelis
authors.initials: C
authors.lastname: Verhoef
authors.affiliation: Department of Radiotherapy, Erasmus MC Cancer Institute, Rotterdam, the Netherlands.
authors.forename: Joost J
authors.initials: JJ
authors.lastname: Nuyttens
authors.affiliation: Department of Medical Oncology, Erasmus MC Cancer Institute, Rotterdam, the Netherlands.
authors.forename: Esther
authors.initials: E
authors.lastname: van Meerten
authors.affiliation: Department of Surgery, Division of Surgical Oncology, Erasmus MC Cancer Institute, Rotterdam, the Netherlands.
authors.forename: Joost
authors.initials: J
authors.lastname: Rothbarth
authors.affiliation: Department of Surgery, Division of Surgical Oncology, Radboud University Nijmegen Medical Center, Nijmegen, the Netherlands.
authors.forename: Johannes H W
authors.initials: JH
authors.lastname: de Wilt
authors.affiliation: Department of Surgery, Division of Surgical Oncology, Erasmus MC Cancer Institute, Rotterdam, the Netherlands. Electronic address: j.burger@erasmusmc.nl.
authors.forename: Jacobus W A
authors.initials: JW
authors.lastname: Burger
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D018572:Disease-Free Survival; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007432:Intraoperative Period; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D020360:Neoadjuvant Therapy / Q000379:methods; D009364:Neoplasm Recurrence, Local / Q000517:prevention & control*; D011878:Radiotherapy / Q000379:methods*; D012004:Rectal Neoplasms / Q000532:radiotherapy* / Q000601:surgery*; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D055815:Young Adult