title: Circulating cell-free DNA: a promising marker of pathologic tumor response in rectal cancer patients receiving preoperative chemoradiotherapy.
abstract: OBJECTIVE
  The circulating cell-free DNA (cfDNA) in plasma has been reported to be a marker of cancer detection. The aim of this study was to investigate whether the cfDNA has a role as response biomarker in patients receiving preoperative chemoradiotherapy (CRT) for rectal cancer.
  
  
  METHODS
  Sixty-seven patients (median age 61 years; male/female 42/25) who underwent CRT for rectal cancer were evaluated. After tumor regression grade (TRG) classification was made, the patients were classified as having disease that responded (TRG 1-2) and that did not respond (TRG 3-5) to therapy. Plasma samples were obtained from patients before and after CRT. The cfDNA levels were analyzed by quantitative real-time polymerase chain reaction of β-globin. On the basis of the Alu repeats, the cfDNA was considered as either total (fragments of 115 bp, Alu 115) or tumoral (fragments of 247 bp, Alu 247). The association between the pre- or post-CRT levels and between variations during CRT of the Alu 247, Alu 115 repeat, and Alu 247/115 ratio (cfDNA integrity index) and the pathologic tumor response was analyzed.
  
  
  RESULTS
  The baseline levels of cfDNA were not associated with tumor response. The post-CRT levels of the cfDNA integrity index were significantly lower in responsive compared to nonresponsive disease (P = 0.0009). Both the median value of the Alu 247 repeat and the cfDNA integrity index decreased after CRT in disease that responded to therapy (P < 0.005 and P < 0.005, respectively) compared to disease that did not respond to therapy (P = 0.83 and P = 0.726, respectively). The results of the multivariable logistic regression analysis showed that only the cfDNA integrity index was significantly and independently associated with tumor response to treatment.
  
  
  CONCLUSIONS
  The plasma levels of the longer fragments (Alu 247) of cfDNA and the cfDNA integrity index are promising markers to predict tumor response after preoperative CRT for rectal cancer.
authors.affiliation: Department of Oncological and Surgical Sciences, 2nd Surgical Clinic, University of Padova, Padova, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Agostini
authors.forename: Salvatore
authors.initials: S
authors.lastname: Pucciarelli
authors.forename: Maria Vittoria
authors.initials: MV
authors.lastname: Enzo
authors.forename: Paola
authors.initials: P
authors.lastname: Del Bianco
authors.forename: Marta
authors.initials: M
authors.lastname: Briarava
authors.forename: Chiara
authors.initials: C
authors.lastname: Bedin
authors.forename: Isacco
authors.initials: I
authors.lastname: Maretto
authors.forename: Maria Luisa
authors.initials: ML
authors.lastname: Friso
authors.forename: Sara
authors.initials: S
authors.lastname: Lonardi
authors.forename: Claudia
authors.initials: C
authors.lastname: Mescoli
authors.forename: Paola
authors.initials: P
authors.lastname: Toppan
authors.forename: Emanuele
authors.initials: E
authors.lastname: Urso
authors.forename: Donato
authors.initials: D
authors.lastname: Nitti
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics* / Q000473:pathology / Q000628:therapy; D000328:Adult; D000368:Aged; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D014408:Biomarkers, Tumor / Q000097:blood / Q000235:genetics; D016190:Carboplatin / Q000008:administration & dosage; D016022:Case-Control Studies; D059248:Chemoradiotherapy; D004247:DNA / Q000097:blood* / Q000235:genetics*; D005260:Female; D005472:Fluorouracil / Q000008:administration & dosage; D005500:Follow-Up Studies; D006801:Humans; D002955:Leucovorin / Q000008:administration & dosage; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D009944:Organoplatinum Compounds / Q000008:administration & dosage; D000077150:Oxaliplatin; D010865:Pilot Projects; D060888:Real-Time Polymerase Chain Reaction; D012004:Rectal Neoplasms / Q000235:genetics* / Q000473:pathology / Q000628:therapy; D015996:Survival Rate; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D014408:Biomarkers, Tumor; D009944:Organoplatinum Compounds; D000077150:Oxaliplatin; D004247:DNA; D016190:Carboplatin; D002955:Leucovorin; D005472:Fluorouracil