to the letter to the editor ‘Borderline resectable pancreatic cancer: an evolving concept’

We thank the authors for their generous and thoughtful comments [1] on our article entitled “Borderline resectable pancreatic cancer: conceptual evolution and current approach to image-based classification,” recently published in Annals of Oncology [2]. Regarding the possible role for endoscopic ultrasound (EUS) in the initial staging of borderline resectable pancreatic cancer (BRPC), we believe that EUS plays a crucial but complementary role to computed tomography (CT) in the initial detection and management of many pancreatic lesions. The compelling study by Glazer et al. [3] suggests that EUS may have a role in assessing for venous involvement, but the highly selected population (only patients who went to surgery; 97% R0 resection rate) and small sample size (n1⁄4 62) of this study necessitates additional data to confirm that this diagnostic advantage persists in an unselected population and to define the role of such information in the treatment decision pathway. The authors also propose a potential role for positron emission tomography (PET)-CT in evaluating response to neoadjuvant therapy for BRPC. While the role of [F]2-fluoro-2-deoxy-Dglucose (FDG)-PET in the primary staging of pancreatic cancer is not currently well defined, it can certainly be a useful adjunct for assessing otherwise ambiguous systemic lesions, and potentially when used for therapy monitoring compared to staging or restaging [4]. However, PET sensitivity is limited for lesions <1 cm, and is suboptimal for evaluating the degree of vascular involvement as FDG uptake within the primary mass frequently obscures recognition of adjacent uptake within the blood pool [5]. Recent NCCN guidelines acknowledge these limitations and state that the role for PET/CT remains unclear, primarily to be considered as a possible adjunct per institutional protocol, specifically in the detection of distant metastatic lesions in certain high-risk patients, but under no circumstances a substitute for pancreatic protocol CT [6]. While FDG-PET may have a future role in assessing response to therapy, additional research will be necessary to determine if and when the potential prognostic data provided by this modality should affect management decisions. There is not sufficient evidence, e.g. to say that FDG-PET nonresponders should forego surgery, or that FDG-PET complete responders could forego adjuvant therapy. In the absence of such data, FDG-PET remains primarily a research tool in this setting, though a “biological-anatomical” definition of BRPC may one day in the future be possible as both imaging techniques and non-imaging criteria continue to evolve. J. W. Gilbert, B. Wolpin, T. Clancy, J. Wang, H. Mamon, A. B. Shinagare, J. Jagannathan & M. Rosenthal Department of Imaging, Dana-Farber Cancer Institute, Boston; Department of Radiology, Brigham and Women’s Hospital, Boston; Harvard Medical School, Boston; Department of Medical Oncology, Dana-Farber Cancer Institute, Boston; Division of Surgical Oncology, Department of Surgery, Brigham and Women’s Hospital and Gastrointestinal Surgical Center, Dana-Farber/Brigham and Women’s Cancer Center, Boston; Department of Radiation Oncology, Dana-Farber Cancer Institute and Brigham and Women’s Hospital, Boston, USA (*E-mail: jwgilbertmd@icloud.com)