ORIGINAL ARTICLE F-18 FDG PET/CT in the assessment of patients with unexplained CEA rise after surgical curative resection for colorectal cancer S. Giacomobono & R. Gallicchio & D. Capacchione & A. Nardelli & D. Gattozzi & G. Lettini & L. Molinari & P. Mainenti & A. Cammarota & G. Storto Accepted: 26 June 2013 # Springer-Verlag Berlin Heidelberg 2013 Abstract Purpose We evaluated the role of quantitative assessment by maximum standardized uptake value (SUVmax) on F- 18 fluorodeoxyglucose [F-18]FDG positron emission tomography/computed tomography (PET/CT) in stratify- ing colorectal cancer (CRC) patients with unexplained carcinoembryonic antigen (CEA) rise after surgical cura- tive resection. Material and methods Fortyasymptomaticpatients(meanage, 64±12 years) with previous CRC and current serum CEA levels >5 ng/ml underwent [F-18] FDG PET/CT 13±3 months after complete surgical resection. The SUVmax was registered on anastomosis and peri-anastomotic tissue lesions, if present. The patients were followed for 24±9 months thereafter. Re- intervention, evidence of newly discovered distant metastases, and death were recognized as main events and constituted surro- gateendpoints.Thereceiver-operator-curve(ROC)analysiswas performed to estimate the optimal SUVmax cut-off to predict patients at high risk of main events. PET/CT results were then related to disease outcome (overall survival; OS). Results The mean SUVmax at the anastomotic site was 6.2±3 (range 2.6–15). At multivariate logistic regression analysis, the anastomotic SUVmax remained as the only significant contributor to the prediction of the events (p =0.004; OR 1.97). The ROC analysis recognized that the optimal threshold of SUVmax to differentiate patients was 5.7. A worse OS was observed in patients presenting with a SUVmax greater than 5.7 as compared to those having lesser (median survival: 16 vs. 31 months; p =0.002). Conclusions The quantitative assessment by SUVmax on [F-18]FDG PET/CT may be helpful in patients presenting with unexplained CEA rise after curative resection of CRC, by identifying those at risk of main events. Keywords Colorectal cancer . [F-18]FDG PET/CT . Loco-regional relapse . Quantitative assessment Introduction Postoperative follow-up of the asymptomatic patients with rising serum carcinoembryonic antigen (CEA) levels after the curative resection for colorectal cancer (CRC) represents a clinical challenge. Although CRC may constitute a rather curable cancer [1, 2] it becomes a distressing disease for patients who suffer from unknown metastases, recurrences, or even relapse [3]. Cure is still possible, for selected pa- tients, however, since the surgical resection provides the best chance for treatment, and radio-chemotherapy given in a (neo-)adjuvant fashion can serve as a valuable adjunct when the survival of patients complying with CRC improved over the last 3 decades. This may be due to better treatment options as well as early detection through screening. Loco- regional pelvic recurrences and liver metastases are the ma- jor sites of relapse after resection of CRC. The recurrence occurs in one third of patients within the first 2 years after S. Giacomobono : R. Gallicchio : D. Capacchione : G. Lettini : L. Molinari : A. Cammarota : G. Storto Istituto di Ricerca e Cura a Carattere Scientifico (IRCCS), Centro di Riferimento Oncologico di Basilicata (CROB), Rionero in Vulture, Italy A. Nardelli : P. Mainenti Istituto di Biostrutture e Bioimmagini, Consiglio Nazionale delle Ricerche (CNR), Naples, Italy D. Gattozzi University of Texas, Southwestern, Dallas, USA G. Storto (*) Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Centro di Riferimento Oncologico di Basilicata (CROB), Via P. Pio 1, 85028 Rionero in Vulture, Italy e-mail: giosto24@hotmail.com Int J Colorectal Dis DOI 10.1007/s00384-013-1747-0