Gram-negative bacteremia as a clinical marker of occult malignancy

Objectives: Gram-negative bacteremia may be a harbinger of occult cancer. We examined the risk of cancer following hospitalization with bacteremia. Methods: Using medical databases, we conducted a nationwide population-based cohort study of all Danes with a discharge diagnosis of Gram-negative bacteremia during 1994-2013. We calculated absolute risks and standardized incidence ratios (SIRs) of cancer, comparing the observed risk to that expected in the general population. Results: We observed 1379 cancers vs. 988 expected among 11,753 patients with Gram-negative bacteremia, corresponding to an overall SIR of 1.40 (95% confidence interval (CI): 1.32-1.47). During the first 6 months following the bacteremia diagnosis, the SIR for cancer was 3.33-fold (95% CI: 2.99-3.69) increased, corresponding to an absolute risk of 3.05%. The increased risk stemmed mainly from higher than expected occurrence of gastrointestinal cancer (3- to 13-fold higher), genitourinary cancer (4- to 10-fold higher), non-Hodgkin lymphoma (5-fold higher), non-specified metastatic cancer (5-fold higher), and breast and lung cancer (2-fold higher). The 6-12 months SIR for any cancer was 1.46 (95% CI: 1.22-1.72), and beyond 1 year of follow-up, the SIR declined to 1.13 (95% CI: 1.05-1.20). Conclusions: Gram-negative bacteremia is a clinical marker of occult cancer. (C) 2016 The British Infection Association. Published by Elsevier Ltd. All rights reserved.