title: Extent of field change in colorectal cancers with BRAF mutation.
abstract: Sporadic colorectal cancers with BRAF mutations constitute two distinct subgroups of colorectal cancers. Recent studies have linked the presence of the BRAF mutation to a familial inheritance pattern. This was a proof-of-concept study that aimed to examine: (a) the extent of field change in sporadic colorectal cancers with BRAF mutation; and (b) the extent of resection margins required and the pattern of DNA mismatch repair protein loss in these tumours.
  
  
  
  Eight microsatellite instability-high tumours with positive BRAF mutation from an existing histopathological database were selected for BRAF mutation and mismatch repair protein analysis.
  
  
  
  All the resection margins were negative for BRAF mutation. Three tumours had loss of MLH1 and PMS2 expressions, and five tumours had no protein loss. Six peritumoral tissues were negative and one was positive for BRAF mutation.
  
  
  
  The results suggest that any early field change effect is restricted to the immediate vicinity of the tumour and is not a pan-colonic phenomenon. Current guidelines on resection margins are adequate for BRAF mutation-positive colorectal cancers. Any suggestion of a hereditary link to these tumours is likely not related to germline BRAF gene mutations. The pattern of protein loss reinforces previous findings for the two subgroups of BRAF mutation-positive colorectal cancers.
authors.affiliation: Department of General Surgery, Khoo Teck Puat Hospital, Singapore.
authors.forename: Aaron
authors.initials: A
authors.lastname: Poh
authors.affiliation: University Surgical Cluster, National University Hospital, Singapore.
authors.forename: Heidi Sian Ying
authors.initials: HS
authors.lastname: Chang
authors.affiliation: Department of General Surgery, Khoo Teck Puat Hospital, Singapore.
authors.forename: Kok Yang
authors.initials: KY
authors.lastname: Tan
authors.affiliation: Histopathology Translational Research Group, Department of Pathology, Singapore General Hospital, Singapore.
authors.forename: Xin Xiu
authors.initials: XX
authors.lastname: Sam
authors.affiliation: Histopathology Translational Research Group, Department of Pathology, Singapore General Hospital, Singapore.
authors.forename: Avery
authors.initials: A
authors.lastname: Khoo
authors.affiliation: Department of Pathology, National University Hospital, Singapore.
authors.forename: Shoa Nian
authors.initials: SN
authors.lastname: Choo
authors.affiliation: Department of Pathology, National University Hospital, Singapore.
authors.forename: Min En
authors.initials: ME
authors.lastname: Nga
authors.affiliation: Department of Pathology, Singapore General Hospital, Singapore.
authors.forename: Wei Keat
authors.initials: WK
authors.lastname: Wan
mesh_terms: D015179:Colorectal Neoplasms / Q000235:genetics* / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D053842:Microsatellite Instability; D009154:Mutation; D009362:Neoplasm Metastasis; D010534:Peritoneal Neoplasms / Q000473:pathology / Q000556:secondary; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics*; D013274:Stomach Neoplasms / Q000473:pathology / Q000556:secondary
chemical_list: C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf
keywords: BRAF mutation; colorectal cancer