title: Predicting pathological complete response to neoadjuvant chemoradiotherapy in locally advanced rectal cancer: a systematic review.
abstract: OBJECTIVE
  Approximately 20% of patients treated with neoadjuvant chemoradiotherapy (nCRT) for locally advanced rectal cancer achieve a pathological complete response (pCR) while the remainder derive the benefit of improved local control and downstaging and a small proportion show a minimal response. The ability to predict which patients will benefit would allow for improved patient stratification directing therapy to those who are likely to achieve a good response, thereby avoiding ineffective treatment in those unlikely to benefit.
  
  
  METHODS
  A systematic review of the English language literature was conducted to identify pathological factors, imaging modalities and molecular factors that predict pCR following chemoradiotherapy. PubMed, MEDLINE and Cochrane Database searches were conducted with the following keywords and MeSH search terms: 'rectal neoplasm', 'response', 'neoadjuvant', 'preoperative chemoradiation', 'tumor response'. After review of title and abstracts, 85 articles addressing the prediction of pCR were selected.
  
  
  RESULTS
  Clear methods to predict pCR before chemoradiotherapy have not been defined. Clinical and radiological features of the primary cancer have limited ability to predict response. Molecular profiling holds the greatest potential to predict pCR but adoption of this technology will require greater concordance between cohorts for the biomarkers currently under investigation.
  
  
  CONCLUSIONS
  At present no robust markers of the prediction of pCR have been identified and the topic remains an area for future research. This review critically evaluates existing literature providing an overview of the methods currently available to predict pCR to nCRT for locally advanced rectal cancer. The review also provides a comprehensive comparison of the accuracy of each modality.
authors.affiliation: Division of Cancer Surgery, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia.|Epworth Healthcare, Melbourne, Victoria, Australia.|Austin Academic Centre, University of Melbourne, Parkville, Victoria, Australia.
authors.forename: J E
authors.initials: JE
authors.lastname: Ryan
authors.affiliation: Division of Cancer Surgery, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia.
authors.forename: S K
authors.initials: SK
authors.lastname: Warrier
authors.affiliation: Division of Cancer Surgery, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia.
authors.forename: A C
authors.initials: AC
authors.lastname: Lynch
authors.affiliation: Differentiation and Transcription Laboratory, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia.|Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, Victoria, Australia.
authors.forename: R G
authors.initials: RG
authors.lastname: Ramsay
authors.affiliation: Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, Victoria, Australia.|Cancer Biology and Surgical Oncology Laboratory, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia.
authors.forename: W A
authors.initials: WA
authors.lastname: Phillips
authors.affiliation: Division of Cancer Surgery, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia.
authors.forename: A G
authors.initials: AG
authors.lastname: Heriot
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis; D059248:Chemoradiotherapy; D006801:Humans; D020360:Neoadjuvant Therapy; D009364:Neoplasm Recurrence, Local / Q000209:etiology* / Q000473:pathology; D012004:Rectal Neoplasms / Q000473:pathology* / Q000628:therapy; D018570:Risk Assessment / Q000379:methods; D016896:Treatment Outcome
chemical_list: D014408:Biomarkers, Tumor
keywords: Rectal cancer; pathologic complete response; prediction