LAUSR

Dear Editor, We read with interest the expert opinion from Panzuto and colleagues [1] on the development of pancreatic exocrine insufficiency (PEI) secondary to somatostatin analogue (SSA) therapy in patients with gastroenteropancreatic neuroendocrine neoplasia (GEP-NENs). We concur with the suggestion that efficient and effective diagnosis of PEI in GEP-NENs is important but complicated due to overlap in symptoms of PEI, and other gastrointestinal pathologies associated with NENs [2]. The impact of treatment for PEI can be highly effective as reported in both studies from Saif et al and Rinzivillo et al [3,4]. Pancreatic enzyme replacement therapy (PERT) has been shown to be associated with improved survival among patients with pancreatic adenocarcinoma [5], though evidence for PERT in the setting of NENs is scarce. We challenge the authors’ suggestion that diagnosis of PEI is ‘easy’. The widespread use of the Faecal elastase-1 (FE-1) stool test relates to its acceptable sensitivity and lack of invasiveness. However, with experience from our own practice, FE1 is a cumbersome test for both patients and laboratory staff. Additionally, evidence for its accuracy is scarce and conflicting [6–9]. Our center is currently conducting a prospective, observational, cohort study to determine the incidence of PEI in this patient cohort, before and after they receive treatment with SSA. Within the study, we are comparing two diagnostic tests for PEI: FE-1 and C-labeled mixed triglyceride (CMTG) breath test. The latter boasts superior accuracy and reliability to the FE-1 test in the literature. It is a potential alternative to FE-1 for PEI diagnosis, though it is not in widespread use due to expense, requirement of strict control measures and a 6-hour testing timeframe [10,11]. We look forward to reporting our results in due course. We agree with the authors’ recommendation for a large prospective study to enhance current understanding of this condition, whilst encouraging exploration of alternative diagnostic strategy for PEI.