title: Analysis of circulating tumour DNA to monitor disease burden following colorectal cancer surgery.
abstract: OBJECTIVE
  To develop an affordable and robust pipeline for selection of patient-specific somatic structural variants (SSVs) being informative about radicality of the primary resection, response to adjuvant therapy, incipient recurrence and response to treatment performed in relation to diagnosis of recurrence.
  
  
  METHODS
  We have established efficient procedures for identification of SSVs by next-generation sequencing and subsequent quantification of 3-6 SSVs in plasma. The consequence of intratumour heterogeneity on our approach was assessed. The level of circulating tumour DNA (ctDNA) was quantified in 151 serial plasma samples from six relapsing and five non-relapsing colorectal cancer (CRC) patients by droplet digital PCR, and correlated to clinical findings.
  
  
  RESULTS
  Up to six personalised assays were designed for each patient. Our approach enabled efficient temporal assessment of disease status, response to surgical and oncological intervention, and early detection of incipient recurrence. Our approach provided 2-15 (mean 10) months' lead time on detection of metastatic recurrence compared to conventional follow-up. The sensitivity and specificity of the SSVs in terms of detecting postsurgery relapse were 100%.
  
  
  CONCLUSIONS
  We show that assessment of ctDNA is a non-invasive, exquisitely specific and highly sensitive approach for monitoring disease load, which has the potential to provide clinically relevant lead times compared with conventional methods. Furthermore, we provide a low-coverage protocol optimised for identifying SSVs with excellent correlation between SSVs identified in tumours and matched metastases. Application of ctDNA analysis has the potential to change clinical practice in the management of CRC.
authors: Department of Molecular Medicine, Aarhus University Hospital, Aarhus, Denmark.
authors: Thomas
authors: T
authors: Reinert
authors: Department of Molecular Medicine, Aarhus University Hospital, Aarhus, Denmark.
authors: Lone V
authors: LV
authors: Schøler
authors: Department of Molecular Medicine, Aarhus University Hospital, Aarhus, Denmark.
authors: Rune
authors: R
authors: Thomsen
authors: Department of Molecular Medicine, Aarhus University Hospital, Aarhus, Denmark.
authors: Heidi
authors: H
authors: Tobiasen
authors: Department of Molecular Medicine, Aarhus University Hospital, Aarhus, Denmark.
authors: Søren
authors: S
authors: Vang
authors: Department of Molecular Medicine, Aarhus University Hospital, Aarhus, Denmark.
authors: Iver
authors: I
authors: Nordentoft
authors: Department of Molecular Medicine, Aarhus University Hospital, Aarhus, Denmark.
authors: Philippe
authors: P
authors: Lamy
authors: Department of Surgical Gastroenterology, Aarhus University Hospital, Aarhus, Denmark.
authors: Anne-Sofie
authors: AS
authors: Kannerup
authors: Department of Surgical Gastroenterology, Aarhus University Hospital, Aarhus, Denmark.
authors: Frank V
authors: FV
authors: Mortensen
authors: Institute of Pathology, Aarhus University Hospital, Aarhus, Denmark.
authors: Katrine
authors: K
authors: Stribolt
authors: Institute of Pathology, Aarhus University Hospital, Aarhus, Denmark.
authors: Stephen
authors: S
authors: Hamilton-Dutoit
authors: Department of Surgical Gastroenterology, University of Copenhagen, Hvidovre Hospital, Hvidovre, Denmark.
authors: Hans J
authors: HJ
authors: Nielsen
authors: Department of Surgery P, Aarhus University Hospital, Aarhus, Denmark.
authors: Søren
authors: S
authors: Laurberg
authors: Department of Clinical Biochemistry, Vejle Hospital, Vejle, Denmark.
authors: Niels
authors: N
authors: Pallisgaard
authors: Department of Molecular Medicine, Aarhus University Hospital, Aarhus, Denmark.
authors: Jakob S
authors: JS
authors: Pedersen
authors: Department of Molecular Medicine, Aarhus University Hospital, Aarhus, Denmark.
authors: Torben F
authors: TF
authors: Ørntoft
authors: Department of Molecular Medicine, Aarhus University Hospital, Aarhus, Denmark.
authors: Claus L
authors: CL
authors: Andersen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000097:blood; D015179:Colorectal Neoplasms / Q000235:genetics / Q000473:pathology / Q000601:surgery*; D003107:Colorectal Surgery; D004273:DNA, Neoplasm / Q000097:blood*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D009367:Neoplasm Staging; D016133:Polymerase Chain Reaction; D020641:Polymorphism, Single Nucleotide; D012680:Sensitivity and Specificity; D017422:Sequence Analysis, DNA
chemical_list: D014408:Biomarkers, Tumor; D004273:DNA, Neoplasm
keywords: Colon cancer; Droplet digital PCR; circulating tumor DNA; mate-pair; plasma