title: Retrospective assessment of patterns of recurrence relative to radiotherapy volumes for adjuvant conformal chemoradiotherapy in gastric cancer.
abstract: BACKGROUND
  Since the Intergroup 0116 study was published in 2000, adjuvant postoperative chemoradiotherapy using CT-planned and 3D conformal/intensity-modulated radiotherapy has been offered routinely to fit patients with resected gastric cancer at Princess Margaret Hospital .The objective of this study was to analyze patterns of disease recurrence with respect to the radiotherapy volumes.
  
  
  METHODS
  For the date and site (local, locoregional, or distant) of the first recurrence, medical records were reviewed for all patients treated at Princess Margaret Hospital with adjuvant chemoradiotherapy for resected gastric adenocarcinoma (January 1, 2000 to November 30, 2009). Patients whose recurrences were limited to local and/or regional sites were selected for further analysis. Available diagnostic imaging of the recurrence site was registered to the original planning radiotherapy dataset for contouring. If necessary to respect changes in anatomy, the contour was translocated on the basis of anatomic descriptors. The center of mass for each recurrence was identified as a point and its location was categorized according to the isodose encompassing it; in field (90 % or more), marginal (50-89 %), or out of field (less than 50 %).
  
  
  RESULTS
  Of all 197 patients, 14 (7 %) had isolated locoregional failure, constituting 20 % of all 71 patients with a recurrence. Successful fusions were feasible in five cases. Of these recurrences, four were in field and one was marginal. In a further four cases, visual inspection was used, showing one in-field recurrence, one marginal recurrence, and two out-of-field recurrences. In five patients, either a useable original dataset or diagnostic imaging of the recurrence was not available.
  
  
  CONCLUSIONS
  The rates of isolated local/locoregional tumor recurrence in this study were low. Of the small number of recurrences available for analysis, most (five of nine) were in field. Further studies involving a larger cohort of patients might allow a more meaningful analysis of trends in the recurrence site with evolving radiotherapy techniques.
authors.affiliation: Department of Radiation Oncology, Princess Margaret Cancer Centre, 610 University Avenue, 5th Floor, Toronto, ON, M5G 2M9, Canada. tatiana.conrad@rmp.uhn.on.ca.
authors.forename: Tatiana
authors.initials: T
authors.lastname: Conrad
authors.affiliation: Department of Surgery, University Health Network, Toronto, Canada.
authors.forename: Steve
authors.initials: S
authors.lastname: MacLellan
authors.affiliation: Department of Radiation Oncology, Princess Margaret Cancer Centre, 610 University Avenue, 5th Floor, Toronto, ON, M5G 2M9, Canada.
authors.forename: Zahra
authors.initials: Z
authors.lastname: Kassam
authors.affiliation: Department of Medical Oncology, Princess Margaret Cancer Centre, Toronto, Canada.
authors.forename: Helen
authors.initials: H
authors.lastname: Mackay
authors.affiliation: Department of Radiology, University Health Network, Toronto, Canada.
authors.forename: Ida
authors.initials: I
authors.lastname: Khalili
authors.affiliation: Department of Statistics, Princess Margaret Cancer Centre, Toronto, Canada.
authors.forename: Jenna
authors.initials: J
authors.lastname: Sykes
authors.affiliation: Department of Radiation Oncology, Princess Margaret Cancer Centre, 610 University Avenue, 5th Floor, Toronto, ON, M5G 2M9, Canada.
authors.forename: Tom
authors.initials: T
authors.lastname: Purdie
authors.affiliation: Department of Surgery, University Health Network, Toronto, Canada.
authors.forename: Allan
authors.initials: A
authors.lastname: Okrainec
authors.affiliation: Department of Radiation Oncology, Princess Margaret Cancer Centre, 610 University Avenue, 5th Floor, Toronto, ON, M5G 2M9, Canada.
authors.forename: Jolie
authors.initials: J
authors.lastname: Ringash
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D059186:Chemoradiotherapy, Adjuvant; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000453:epidemiology* / Q000473:pathology; D009367:Neoplasm Staging; D011379:Prognosis; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D020266:Radiotherapy, Conformal; D012189:Retrospective Studies; D013274:Stomach Neoplasms / Q000473:pathology / Q000628:therapy*; D055815:Young Adult
keywords: Chemoradiotherapy; Conformal radiotherapy; Gastric cancer; Patterns of failure; Radiotherapy volumes