title: Early prediction of response by ¹⁸F-FDG PET/CT during preoperative therapy in locally advanced rectal cancer: a systematic review.
abstract: OBJECTIVE
  To assess the predictive value of fluorine-18-fluorodeoxyglucose ((18)F-FDG) positron emission tomography/computed tomography (PET/CT) in early assessing response during neo-adjuvant chemoradiotherapy (CRT) in patients with locally advanced rectal cancer.
  
  
  METHODS
  A systematic review was performed by search of MEDLINE Library for the following terms: "rectal carcinoma OR rectal cancer", "predictive OR prediction OR response assessment OR response OR assessment", "early OR ad interim", "therapy", "FDG OR (18)F-FDG", "PET OR PET/CT". Articles performed by the use of stand-alone PET scanners were excluded.
  
  
  RESULTS
  10 studies met the inclusion criteria, including 302 patients. PET/CT demonstrated a good early predictive value in the global cohort (mean sensitivity = 79%; mean specificity = 78%). SUV and its percentage decrease (response index = RI) were calculated in all studies. A higher accuracy was demonstrated for RI (mean sensitivity = 82%; pooled specificity = 85%) with a mean cut-off of 42%. The mean time point to perform PET scan during CRT resulted to be at 1.85 weeks. Some PET parameters resulted to be both predictive and not statistical predictive of response, maybe due to the small population and few studies bias.
  
  
  CONCLUSIONS
  PET showed high accuracy in early prediction response during preoperative CRT, increased with the use of RI as parameter. In the era of tailored treatment, the precocious assessment of non-responder patients allows modification of the subsequent strategy especially the timing and the type of surgical approach.
authors: Department of Nuclear Medicine, PET Unit, Nuclear Medicine & PET/CT Centre, Santa Maria della Misericordia Hospital, Viale Tre Martiri, 140, 45100 Rovigo, Italy. Electronic address: maffione.marghe@libero.it.
authors: A M
authors: AM
authors: Maffione
authors: Radiotherapy Unit, Santa Maria della Misericordia Hospital, Rovigo, Italy.
authors: S
authors: S
authors: Chondrogiannis
authors: Radiotherapy Unit, Santa Maria della Misericordia Hospital, Rovigo, Italy.
authors: C
authors: C
authors: Capirci
authors: Surgical Oncology Unit, Santa Maria della Misericordia Hospital, Rovigo, Italy.
authors: F
authors: F
authors: Galeotti
authors: Medical Oncology Unit, Sant'Antonio Hospital, Padova, Italy.
authors: A
authors: A
authors: Fornasiero
authors: Medical Oncology Unit, Santa Maria della Misericordia Hospital, Rovigo, Italy.
authors: G
authors: G
authors: Crepaldi
authors: Department of Nuclear Medicine, PET Unit, Nuclear Medicine & PET/CT Centre, Santa Maria della Misericordia Hospital, Viale Tre Martiri, 140, 45100 Rovigo, Italy.
authors: G
authors: G
authors: Grassetto
authors: Department of Nuclear Medicine, PET Unit, Nuclear Medicine & PET/CT Centre, Santa Maria della Misericordia Hospital, Viale Tre Martiri, 140, 45100 Rovigo, Italy.
authors: L
authors: L
authors: Rampin
authors: Department of Nuclear Medicine, PET Unit, Nuclear Medicine & PET/CT Centre, Santa Maria della Misericordia Hospital, Viale Tre Martiri, 140, 45100 Rovigo, Italy.
authors: M C
authors: MC
authors: Marzola
authors: Department of Nuclear Medicine, PET Unit, Nuclear Medicine & PET/CT Centre, Santa Maria della Misericordia Hospital, Viale Tre Martiri, 140, 45100 Rovigo, Italy.
authors: D
authors: D
authors: Rubello
mesh_terms: D002277:Carcinoma / Q000000981:diagnostic imaging* / Q000473:pathology / Q000628:therapy; D059186:Chemoradiotherapy, Adjuvant; D019788:Fluorodeoxyglucose F18; D006801:Humans; D064847:Multimodal Imaging; D020360:Neoadjuvant Therapy; D049268:Positron-Emission Tomography; D011379:Prognosis; D019275:Radiopharmaceuticals; D012004:Rectal Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000628:therapy; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
keywords: Complete response; Early; FDG; Locally advanced rectal cancer; Major response; PET; Pre-operative chemoradiotherapy; Predictive value; ad interim