title: Cause-specific colostomy rates after radiotherapy for anal cancer: a Danish multicentre cohort study.
abstract: OBJECTIVE
  In anal cancer, colostomy-free survival is a measure of anal sphincter preservation after treatment with radiotherapy or chemoradiotherapy. Failure to control anal cancer and complications of treatment are alternative indications for colostomy. However, no data exist on cause-specific colostomy rates. We examined this in a cohort study.
  
  
  METHODS
  Through national registries and review of medical records, we identified patients with anal cancer diagnosed from 1995 to 2003 who had curative-intent radiotherapy or chemoradiotherapy in four Danish centers. We computed cumulative incidence of tumor-related colostomy and therapy-related colostomy, treating colostomy and death as competing events. Follow-up started at completion of radiotherapy and continued throughout 2008. We used competing risk regression to compute hazard ratios (HRs) to compare the cumulative incidence of cause-specific colostomies between age, sex, tumor size, chemotherapy, and local excision before radiotherapy.
  
  
  RESULTS
  We included 235 patients with anal cancer. The 5-year cumulative incidences of tumor-related and therapy-related colostomy were 26% (95% CI, 21% to 32%) and 8% (95% CI, 5% to 12%), respectively. Tumor size greater than 6 cm versus less than 4 cm was a risk factor for tumor-related colostomy (adjusted HR, 3.8; 95% CI, 1.7 to 8.1), and local excision before radiotherapy was a risk factor for therapy-related colostomy (adjusted HR, 4.5; 95% CI, 1.5 to 13.5).
  
  
  CONCLUSIONS
  After curative-intent radiotherapy or chemoradiotherapy, one third of patients had a colostomy, of which one third were related to therapy. Large tumor size was associated with a higher risk of tumor-related colostomy, whereas history of prior excision was associated with an increased incidence of therapy-related colostomy.
authors.affiliation: Department of Gastrointestinal Surgery A, Aalborg Hospital, Aarhus University Hospital, Hobrovej 18-22, PO Box 365, DK-9100 Aalborg, Denmark. k.sunesen@rn.dk
authors.forename: Kåre G
authors.initials: KG
authors.lastname: Sunesen
authors.forename: Mette
authors.initials: M
authors.lastname: Nørgaard
authors.forename: Lilli
authors.initials: L
authors.lastname: Lundby
authors.forename: Hanne
authors.initials: H
authors.lastname: Havsteen
authors.forename: Steen
authors.initials: S
authors.lastname: Buntzen
authors.forename: Ole
authors.initials: O
authors.lastname: Thorlacius-Ussing
authors.forename: Søren
authors.initials: S
authors.lastname: Laurberg
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000009:adverse effects; D001005:Anus Neoplasms / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery*; D015331:Cohort Studies; D003125:Colostomy / Q000706:statistics & numerical data*; D003131:Combined Modality Therapy / Q000009:adverse effects; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D011878:Radiotherapy / Q000009:adverse effects; D012307:Risk Factors
chemical_list: D000970:Antineoplastic Agents