title: Timing of adjuvant chemotherapy in colorectal cancer.
abstract: OBJECTIVE
  Delay in commencing adjuvant therapy for colorectal cancer seems to impair survival in some retrospective studies. This study was planned to evaluate its impact on survival.
  
  
  METHODS
  This was a retrospective study enrolling patients registered from 2000 to 2012 in two large cancer-dedicated institutions in Brazil. The primary outcome was overall survival according to early vs late chemotherapy initiation. The interval between the primary surgery and the start of adjuvant chemotherapy was calculated. Survival was estimated using the Kaplan-Meier method and the impact of multiple prognostic factors on survival by Cox regression analysis.
  
  
  RESULTS
  By the end of 2012, a total of 1963 Stage II and III colorectal patients were identified and 1318 patients received adjuvant chemotherapy, with 22% and 46% of those starting adjuvant chemotherapy within 6 weeks and 8 weeks of surgery. The median period of follow-up was 41 months. Patients starting chemotherapy within 6-8 weeks of surgery had longer overall survival compared with those who started after (6 weeks vs later, hazard ratio 0.76, 95% CI 0.57-0.99, P = 0.046; 8 weeks vs later, hazard ratio 0.74, 95% CI 0.59-0.93, P = 0.011). In the multivariate analysis, age, stage, histological grade, angiolymphatic invasion, emergency surgery and preoperative therapy were independent prognostic factors, but the interval between surgery and start of adjuvant therapy was not.
  
  
  CONCLUSIONS
  In this large retrospective study, the standard prognostic factors impacted on survival whereas the timing of adjuvant therapy did not. Patients with delayed adjuvant chemotherapy may have worse prognostic factors which could play a major role in their poor outcome.
authors.affiliation: Instituto de Ensino e Pesquisa São Lucas, São Paulo, Brazil.|Internal Medicine Department, University of Campinas, São Paulo, Brazil.
authors.forename: L V
authors.initials: LV
authors.lastname: Dos Santos
authors.affiliation: Hospital do Câncer, Barretos, Brazil.
authors.forename: T M V
authors.initials: TM
authors.lastname: Faria
authors.affiliation: Núcleo de Oncologia da Bahia - Oncoclínicas do Brasil, Salvador, Brazil.
authors.forename: A B C
authors.initials: AB
authors.lastname: Lima
authors.affiliation: Hospital do Câncer, Barretos, Brazil.
authors.forename: K C
authors.initials: KC
authors.lastname: Abdalla
authors.affiliation: Núcleo de Oncologia da Bahia - Oncoclínicas do Brasil, Salvador, Brazil.
authors.forename: E D
authors.initials: ED
authors.lastname: de Moraes
authors.affiliation: Centro Oncológico Antônio Ermírio de Moraes, São Paulo, Brazil.
authors.forename: M R
authors.initials: MR
authors.lastname: Cruz
authors.affiliation: Institute of Cancer Research, Royal Marsden Hospital, London, UK.
authors.forename: J P
authors.initials: JP
authors.lastname: Lima
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000627:therapeutic use; D001938:Brazil; D017024:Chemotherapy, Adjuvant / Q000379:methods*; D015179:Colorectal Neoplasms / Q000188:drug therapy* / Q000473:pathology; D013505:Digestive System Surgical Procedures; D005260:Female; D005472:Fluorouracil / Q000627:therapeutic use; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging; D009944:Organoplatinum Compounds / Q000627:therapeutic use; D000077150:Oxaliplatin; D011379:Prognosis; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D015996:Survival Rate; D013997:Time Factors; D055815:Young Adult
chemical_list: D000970:Antineoplastic Agents; D009944:Organoplatinum Compounds; D000077150:Oxaliplatin; D005472:Fluorouracil
keywords: Chemotherapy; adjuvant; colorectal cancer