title: The impact of adjuvant chemotherapy timing on overall survival following colorectal cancer resection.
abstract: BACKGROUND
  Several studies including two meta-analyses have showed that delay between surgery and adjuvant chemotherapy adversely impacts colorectal cancer survival. This study investigated this impact at a population level over a fifteen year period in England.
  
  
  METHODS
  The Hospital Episode Statistics database was analysed between 1997 and 2012. Colonic cancer and rectal cancer patients were collated and multivariate Cox regression analyses were undertaken to ascertain the relationship between chemotherapy delay and overall survival.
  
  
  RESULTS
  A total of 181 984 patients underwent resection without any reoperation (106 477 (58.5%) having colonic cancer and 75 507 (41.5%) having rectal cancer). In total, 30 836 (16.9%) received adjuvant chemotherapy. 9019 (49.3%), 4573 (25.0%), 2587 (14.1%), 1323 (7.2%) and 804 (4.4%) of 18 306 colonic cancer patients received within 8 weeks, 8-10 weeks, 10-12 weeks, 12-14 weeks and 14-16 weeks, respectively. Sequentially worse overall survival was observed: <8 weeks: Ref; 8-10 wks: Hazard Ratio (HR) 1.09; 10-12 wks: HR 1.13; 12-14 wks HR 1.32 and 14-16 wks: HR 1.32, p < 0.001. 5625 (44.9%), 3087 (24.6%), 1940 (15.5%), 1162 (9.3%) and 716 (5.7%) of 12 530 rectal cancer patients received within 8 weeks, 8-10 weeks, 10-12 weeks, 12-14 weeks and 14-16 weeks, respectively. Sequentially worse overall survival was observed: <8 weeks: Ref; 8-10 wks: HR 1.09; 10-12 wks: HR 1.22; 12-14 wks HR 1.23 and 14-16 wks: HR 1.31, p < 0.001.
  
  
  CONCLUSIONS
  Adjuvant chemotherapy delay adversely impacts colonic and rectal cancer survival. Efforts to prevent complications such as reoperation and to improve access to chemotherapy services, will improve survival in this patient cohort.
authors.affiliation: Surgical Epidemiology, Trials and Outcomes Centre (SETOC), St Mark's Hospital & Academic Institute, Watford Road, Harrow, Middlesex, HA1 3UJ, United Kingdom; Department of Surgery & Cancer, Imperial College London, London SW7 2AZ, United Kingdom. Electronic address: s.nachiappan12@imperial.ac.uk.
authors.forename: S
authors.initials: S
authors.lastname: Nachiappan
authors.affiliation: Surgical Epidemiology, Trials and Outcomes Centre (SETOC), St Mark's Hospital & Academic Institute, Watford Road, Harrow, Middlesex, HA1 3UJ, United Kingdom; Department of Surgery & Cancer, Imperial College London, London SW7 2AZ, United Kingdom.
authors.forename: A
authors.initials: A
authors.lastname: Askari
authors.affiliation: Surgical Epidemiology, Trials and Outcomes Centre (SETOC), St Mark's Hospital & Academic Institute, Watford Road, Harrow, Middlesex, HA1 3UJ, United Kingdom; Department of Surgery & Cancer, Imperial College London, London SW7 2AZ, United Kingdom.
authors.forename: R
authors.initials: R
authors.lastname: Mamidanna
authors.affiliation: Surgical Epidemiology, Trials and Outcomes Centre (SETOC), St Mark's Hospital & Academic Institute, Watford Road, Harrow, Middlesex, HA1 3UJ, United Kingdom; Department of Surgery & Cancer, Imperial College London, London SW7 2AZ, United Kingdom.
authors.forename: A
authors.initials: A
authors.lastname: Munasinghe
authors.affiliation: Surgical Epidemiology, Trials and Outcomes Centre (SETOC), St Mark's Hospital & Academic Institute, Watford Road, Harrow, Middlesex, HA1 3UJ, United Kingdom; Department of Surgery & Cancer, Imperial College London, London SW7 2AZ, United Kingdom.
authors.forename: A
authors.initials: A
authors.lastname: Currie
authors.affiliation: Hammersmith Hospital, 150 Du-Cane Road, London W12 0HS, United Kingdom; Department of Surgery & Cancer, Imperial College London, London SW7 2AZ, United Kingdom.
authors.forename: J
authors.initials: J
authors.lastname: Stebbing
authors.affiliation: Surgical Epidemiology, Trials and Outcomes Centre (SETOC), St Mark's Hospital & Academic Institute, Watford Road, Harrow, Middlesex, HA1 3UJ, United Kingdom; Department of Surgery & Cancer, Imperial College London, London SW7 2AZ, United Kingdom.
authors.forename: O
authors.initials: O
authors.lastname: Faiz
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D017024:Chemotherapy, Adjuvant; D003082:Colectomy; D015179:Colorectal Neoplasms / Q000401:mortality / Q000628:therapy*; D004739:England / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011182:Postoperative Care / Q000379:methods*; D015996:Survival Rate / Q000639:trends; D013997:Time Factors; D055815:Young Adult
chemical_list: D000970:Antineoplastic Agents
keywords: Adjuvant; Chemotherapy; Colorectal neoplasms; Epidemiology; Postoperative period