Impact of Diabetes and Insulin Use on Prognosis in Patients With Resected Pancreatic Cancer: An Ancillary Analysis of NRG Oncology RTOG 9704

Abstract

Diabetes mellitus (DM) has been proposed to be tumorigenic; however, prior studies of the association between DM and survival are conflicting. The goal of this ancillary analysis of RTOG 9704, a randomized controlled trial of adjuvant chemotherapy in pancreatic cancer, was to determine the prognostic effects of DM and insulin use on survival. Eligible patients from RTOG 9704 with available data on DM and insulin use were included. Overall survival (OS) and disease-free survival (DFS) were estimated using the Kaplan-Meier method, and variable levels were compared using log-rank test. Cox proportional hazards models were created to assess the associations among DM, insulin use, and body mass index phenotypes on outcomes. Of 538 patients enrolled from 1998 to 2002, 238 patients were eligible with analyzable DM and insulin use data. Overall 34% of patients had DM and 66% did not. Of patients with DM, 64% had insulin-dependent DM, and 36% had non-insulin-dependent DM. On univariable analysis, neither DM nor insulin dependence were associated with OS or DFS (P > .05 for all). On multivariable analysis, neither DM, insulin use, nor body mass index were independently associated with OS or DFS. Nonwhite race (hazard ratio [HR], 2.18; 95% confidence interval [CI], 1.35-3.50; P = .0014), nodal involvement (HR, 1.74; 95% CI, 1.24-2.45; P = .0015), and carbohydrate antigen 19-9 (CA19-9) ≥90 U/mL (HR, 3.61; 95% CI, 2.32-5.63; P < .001) were associated with decreased OS. Nonwhite race (HR, 1.67; 95% CI, 1.05-2.63; P = .029) and CA19-9 ≥90 U/mL (HR, 2.86; 95% CI, 1.85-4.40; P < .001) were associated with decreased DFS. DM and insulin use were not associated with OS or DFS in patients with pancreatic cancer in this study. Race, nodal involvement, and increased CA19-9 were significant predictors of outcomes. These data might apply to the more modern use of neoadjuvant therapies for potentially resectable pancreatic cancer.