title: Timing of adjuvant chemotherapy and its relation to survival among patients with stage III colon cancer.
abstract: BACKGROUND
  Currently available data suggest that delaying the start of adjuvant chemotherapy in colon cancer patients has a detrimental effect on survival. We analysed which factors impact on the timing of adjuvant chemotherapy and evaluated the influence on overall survival (OS).
  
  
  METHODS
  Stage III colon cancer patients who underwent resection and received adjuvant chemotherapy between 2008 and 2013 were selected from the Netherlands Cancer Registry. Timing of adjuvant chemotherapy was subdivided into: ⩽ 4, 5-6, 7-8, 9-10, 11-12 and 13-16 weeks post-surgery. Multivariable regressions were performed to assess the influence of several factors on the probability of starting treatment within 8 weeks post-surgery and to evaluate the association of timing of adjuvant chemotherapy with 5-year OS.
  
  
  RESULTS
  6620 patients received adjuvant chemotherapy, 14% commenced after 8 weeks. Factors associated with starting treatment after 8 weeks were older age (Odds ratio (OR) 65-74 versus < 65 years 1.3 (95% confidence interval (CI): 1.14-1.58); OR ⩾ 75 versus < 65 years 1.6 (1.25-1.94)), emergency resection (OR 1.8 (1.41-2.32)), anastomotic leakage (OR 8.1 (6.14-10.62)), referral to another hospital for adjuvant chemotherapy (OR 1.9 (1.36-2.57)) and prolonged postoperative hospital admission (OR 4.7 (3.30-6.68)). Starting 5-8 weeks post-surgery showed no decrease in OS compared to initiation within 4 weeks (Hazard ratio (HR) 5-6 weeks 0.9 (0.79-1.11); HR 7-8 weeks 1.1 (0.91-1.30)). However, commencing beyond 8 weeks was associated with decreased OS compared to initiation within 8 weeks (HR 9-10 weeks 1.4 (1.21-1.68); HR 11-12 weeks 1.3 (1.06-1.59); HR 13-16 weeks 1.7 (1.23-2.23)).
  
  
  CONCLUSIONS
  Our data support initiating adjuvant chemotherapy in stage III colon cancer patients within 8 weeks post-surgery.
authors.affiliation: Department of Research, Netherlands Comprehensive Cancer Organisation (IKNL), Utrecht, The Netherlands. Electronic address: a.bos@iknl.nl.
authors.forename: A C R K
authors.initials: AC
authors.lastname: Bos
authors.affiliation: Department of Research, Netherlands Comprehensive Cancer Organisation (IKNL), Utrecht, The Netherlands; Department of Public Health, Erasmus MC University Medical Centre, Rotterdam, The Netherlands.
authors.forename: F N
authors.initials: FN
authors.lastname: van Erning
authors.affiliation: Department of Research, Netherlands Comprehensive Cancer Organisation (IKNL), Utrecht, The Netherlands.
authors.forename: Y R B M
authors.initials: YR
authors.lastname: van Gestel
authors.affiliation: Department of Internal Medicine, Catharina Hospital, Eindhoven, The Netherlands.
authors.forename: G J M
authors.initials: GJ
authors.lastname: Creemers
authors.affiliation: Department of Medical Oncology, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: C J A
authors.initials: CJ
authors.lastname: Punt
authors.affiliation: Department of Research, Netherlands Comprehensive Cancer Organisation (IKNL), Utrecht, The Netherlands; Department of Medical Oncology, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: M G H
authors.initials: MG
authors.lastname: van Oijen
authors.affiliation: Department of Research, Netherlands Comprehensive Cancer Organisation (IKNL), Utrecht, The Netherlands; Department of Public Health, Erasmus MC University Medical Centre, Rotterdam, The Netherlands.
authors.forename: V E P P
authors.initials: VE
authors.lastname: Lemmens
mesh_terms: D000368:Aged; D017024:Chemotherapy, Adjuvant; D003106:Colon / Q000187:drug effects* / Q000473:pathology / Q000601:surgery; D003110:Colonic Neoplasms / Q000188:drug therapy* / Q000473:pathology / Q000601:surgery; D003131:Combined Modality Therapy; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D016015:Logistic Models; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009367:Neoplasm Staging; D009426:Netherlands; D017063:Outcome Assessment, Health Care / Q000379:methods / Q000706:statistics & numerical data; D011184:Postoperative Period; D016016:Proportional Hazards Models; D012042:Registries / Q000706:statistics & numerical data; D013997:Time Factors
keywords: Adjuvant chemotherapy; Colon cancer; Delays in chemotherapy; Survival; Timing