title: Review on adjuvant chemotherapy for rectal cancer - why do treatment guidelines differ so much?
abstract: BACKGROUND
  The use of postoperative adjuvant chemotherapy is controversial for rectal adenocarcinoma. Both international and national guidelines display a great span varying from recommending no adjuvant chemotherapy at all, over single drug 5-fluororuacil (5-FU), to combinations of 5-FU/oxaliplatin.
  
  
  METHODS
  A review of the literature was made identifying 24 randomized controlled trials on adjuvant treatment of rectal cancer based on about 10 000 patients. The trials were subdivided into a number of clinically relevant subgroups.
  
  
  RESULTS
  As regards patients treated with preoperative (chemo) radiotherapy, four randomized studies were found where use of adjuvant chemotherapy showed no benefit in survival. Three trials were found in which a subset of patients received preoperative (chemo) radiotherapy. Two of these trials showed a statistically significant benefit of adjuvant chemotherapy. Twenty trials were identified in which the patients did not receive preoperative (chemo) radiotherapy, including five Asian studies in which a statistically significant benefit from adjuvant chemotherapy was reported.
  
  
  CONCLUSIONS
  Most of the data found did not support the use of postoperative adjuvant chemotherapy for patients already treated with preoperative (chemo) radiotherapy. For patients not treated preoperatively, several studies support the use of single agent 5-FU chemotherapy. Treatment guidelines seem to differ according to if preoperative chemoradiation is considered of importance for use of adjuvant chemotherapy and if adjuvant colon cancer studies are considered transferrable to rectal cancer patients regardless of the molecular differences.
authors.affiliation: Department of Oncology, Aalborg University Hospital , Aalborg , Denmark.
authors.forename: Laurids Ø
authors.initials: LØ
authors.lastname: Poulsen
authors.forename: Camilla
authors.initials: C
authors.lastname: Qvortrup
authors.forename: Per
authors.initials: P
authors.lastname: Pfeiffer
authors.forename: Mette
authors.initials: M
authors.lastname: Yilmaz
authors.forename: Ursula
authors.initials: U
authors.lastname: Falkmer
authors.forename: Halfdan
authors.initials: H
authors.lastname: Sorbye
mesh_terms: D000230:Adenocarcinoma / Q000401:mortality / Q000628:therapy*; D000964:Antimetabolites, Antineoplastic / Q000008:administration & dosage; D059248:Chemoradiotherapy; D017024:Chemotherapy, Adjuvant; D018572:Disease-Free Survival; D005472:Fluorouracil / Q000008:administration & dosage; D006801:Humans; D011182:Postoperative Care; D017410:Practice Guidelines as Topic; D011300:Preoperative Care; D016032:Randomized Controlled Trials as Topic; D012004:Rectal Neoplasms / Q000401:mortality / Q000628:therapy*
chemical_list: D000964:Antimetabolites, Antineoplastic; D005472:Fluorouracil