Early prediction of response by (18)F-FDG PET/CT during preoperative therapy in locally advanced rectal cancer: A systematic review.

European journal of surgical oncology : the journal of the European Society of Surgical Oncology and the British Association of Surgical Oncology

PubMedID: 25060221

Maffione AM, Chondrogiannis S, Capirci C, Galeotti F, Fornasiero A, Crepaldi G, Grassetto G, Rampin L, Marzola MC, Rubello D. Early prediction of response by (18)F-FDG PET/CT during preoperative therapy in locally advanced rectal cancer: A systematic review. Eur J Surg Oncol. 2014;.
AIM
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.

MATERIALS AND 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.

CONCLUSION
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.