Metformin Use Is Associated With Longer Progression-Free Survival of Patients With Diabetes and Pancreatic Neuroendocrine Tumors Receiving Everolimus and/or Somatostatin Analogues.

BACKGROUND & AIMS: Metformin seems to have anticancer effects. However, it is not clear whether use of glycemia and metformin affect outcomes of patients with advanced pancreatic neuroendocrine tumors (pNETs). We investigated the association between glycemia and progression-free survival (PFS) of patients with pNETs treated with everolimus and/or somatostatin analogues, as well as the association between metformin use and PFS time. METHODS: We performed a retrospective analysis of 445 patients with advanced pNET treated at 24 medical centers in Italy from 1999 through 2015. Data on levels of glycemia were collected at time of diagnosis of pNET, before treatment initiation, and during treatment with everolimus (with or without somatostatin analogues), octreotide, or lanreotide. Diabetes was defined as prior or current use of glycemia control medication and/or fasting plasma glucose level ≥ 126 mg/dL, hemoglobin A1c ≥ 6.5% (48 mmol/L), or a random sample of plasma glucose ≥ 200 mg/dL (11.1 mmol/L), with reported classic symptoms of hyperglycemia or hyperglycemic crisis. Patients were assigned to groups based on diagnosis of diabetes before or during antitumor therapy. PFS was compared between patients with vs without diabetes. Among patients with diabetes, the association between metformin use and PFS was assessed. We performed sensitivity and landmark analyses to exclude patients who developed diabetes while receiving cancer treatment and to exclude a potential immortal time bias related to metformin intake. RESULTS: PFS was significantly longer in patients with diabetes (median, 32.0 months) than without diabetes (median, 15.1 months) (hazard ratio for patients with vs without diabetes, 0.63; 95% confidence interval, 0.50-0.80; P = .0002). PFS of patients treated with metformin was significantly longer (median PFS, 44.2 months) than for patients without diabetes (hazard ratio for survival of patients with diabetes receiving metformin vs without diabetes, 0.45; 95% confidence interval, 0.32-0.62; P < .00001) and longer than for patients with diabetes receiving other treatments (median PFS, 20.8 months; hazard ratio, 0.49; 95% confidence interval, 0.34-0.69; P < .0001). In multivariable analysis, adjusted for other factors associated with outcomes, metformin was associated with longer PFS but level of glycemia was not. Metformin was associated with increased PFS of patients receiving somatostatin analogues and in those receiving everolimus, with or without somatostatin analogues. Sensitivity and landmark analyses produced similar results. CONCLUSIONS: In a retrospective study of patients with pNETs, we found a significant association between metformin use and longer PFS.

The impact of antithrombotic prophylaxis on infectious complications in cancer patients with central venous catheters: an observational study.

Infections in cancer patients after implantation of a central venous device (CVD) are not infrequent and are potentially serious. The possibility of limiting this complication with antithrombotic drugs is still debated. For this observational study, we recorded the routine management of CVD in cancer patients in 18 oncology centers in Lombardy (northern Italy), assessing the effect of antithrombotic prophylaxis on catheter-related infections. Out of 1410 patients enrolled, 451 received antithrombotic prophylaxis continuously after implantation of the central line. During a median follow-up of 30 months, 57 catheter-related infections were reported in the 1390 patients seen at least once at follow-up visits (4.1% of the whole series), giving an overall incidence of 0.10 infections per 1000 catheter days. This complication was significantly more frequent among patients with an indwelling central venous catheter, or peripherally inserted catheter, than among those with a port device, and the group not given antithrombotic prophylaxis had 0.14 infective complications/1000 CVD days compared with 0.05/1000 CVD days (odds ratio 2.4; 95% confidence interval 1.7-5.0) for those treated. Antithrombotic prophylaxis protected against infections at the catheter exit site and track but not against systemic infections. Confirming earlier evidence, this study found a reduction in catheter-related infections in patients given antithrombotic prophylaxis. However, this reduction, reflecting local infections, seems unlikely to be one of the mechanisms explaining the lower mortality among our patients treated with anticoagulants.