Systematic Review of FDG-PET Prediction of Complete Pathological Response and Survival in Rectal Cancer

Background. Advances in the management of rectal cancer have resulted in an increased application of multimodal therapy with the aim of tailoring therapy to individual patients. Complete pathological response (pCR) is associated with improved survival and may be potentially managed without radical surgical resection. Over the last decade, there has been increasing interest in the ability of functional imaging to predict complete response to treatment. The aim of this review was to assess the role of F-flurordeoxyglucose positron emission tomography (FDG-PET) in prediction of pCR and prognosis in resectable locally advanced rectal cancer. Methods. A search of the MEDLINE and Embase databases was conducted, and a systematic review of the literature investigating positron emission tomography (PET) in the prediction of pCR and survival in rectal cancer was performed. Results. Seventeen series assessing PET prediction of pCR were included in the review. Seven series assessed postchemoradiation SUVmax, which was significantly different between response groups in all six studies that assessed this. Nine series assessed the response index (RI) for SUVmax, which was significantly different between response groups in seven series. Thirteen studies investigated PET response for prediction of survival. Metabolic complete response assessed by SUV2max or visual response and RISUVmax showed strong associations with disease-free survival (DFS) and overall survival (OS). Conclusion. SUV2max and RISUVmax appear to be useful FDG-PET markers for prediction of pCR and these parameters also show strong associations with DFS and OS. FDG-PET may have a role in outcome prediction in patients with advanced rectal cancer. Advances in the management of rectal cancer have resulted in an increased application of multimodal therapy with the aim of tailoring neoadjuvant, surgical, and adjuvant therapy. A key to individualisation of treatment is the ability to accurately assess and predict response to neoadjuvant therapy. Assessment of response has previously focused on response on anatomical imaging, as defined by the response evaluation criteria in solid tumors (RECIST) criteria. However anatomical imaging techniques have not been shown to have sufficient accuracy for clinical application, and other methods for response prediction, including functional imaging techniques such as positron emission tomography (PET), are currently under investigation. PET displays areas of focally increased metabolism through increased uptake of a radio-labelled tracer, usually F-lurordeoxyglucose (FDG). This may be caused by malignancy or benign processes such as inflammation, regeneration, or infection. The response to chemoradiation is variable from no response to a complete pathological response (pCR). The ability to accurately predict patients with a pCR may allow a less radical surgical approach or a nonoperative Society of Surgical Oncology 2014 First Received: 3 March 2014; Published Online: 7 May 2014 A. G. Heriot, MD FRCS (Gen.), FRCSEd, FRACS e-mail: alexander.heriot@petermac.org Ann Surg Oncol (2014) 21:3598–3607 DOI 10.1245/s10434-014-3753-z