Preoperative Glycosylated Hemoglobin A1C Impacts Long-Term Outcomes Following Curative-Intent Resection of Nonfunctional Gastroenteropancreatic Neuroendocrine Tumors

Background: To investigate the impact of preoperative glycosylated hemoglobin A1C (HbA1c) among patients following curative-intent resection of nonfunctional gastroentropancreatic neuroendocrine tumors (GEP-NETs). Methods: Patients who underwent curative-intent resection for GEP-NETs from 2000 to 2020 were identified from the US Neuroendocrine Tumor Study Group (US-NETSG). Preoperative blood HbA1c levels were defined as high HbA1c (≥ 6.5%) versus low HbA1c group (< 6.5%). Impact of HbA1c level on postoperative short-term and long-term overall (OS) were investigated. Results: A total of 130 patients with HbA1c < 6.5% and 60 patients with HbA1c ≥ 6.5% were included. Patients with HbA1c ≥ 6.5% had higher proportion of comorbidities, such as hypertension, obesity, anemia, and lower preoperative albumin levels versus patients with HbA1c < 6.5% (all p < 0.05). In addition, high level of preoperative HbA1c was associated with increased incidence of wound and infectious complications, as well as decreased long-term OS (median OS: high Hb1Ac 89.8 months vs. low Hb1Ac not reached, HR 3.487, p = 0.004) among patients with nonfunctional GEP-NETs, as well as among the subset of pancreatic NET patients (median OS: high Hb1Ac 74.3 months vs. low Hb1Ac not reached, p = 0.004), and patients with normal fasting blood glucose (< 140 mg/dL) (median OS: high Hb1Ac 75.4 months vs. low Hb1Ac not reached, p = 0.001). Conclusions: Hb1Ac might have value as a screening tool to identify high-risk patients following surgical resection of nonfunctional GEP-NETs for consideration of more strict postoperative surveillance and treatment of elevated Hb1Ac level.