Abstract 2525: Neutrophil count, cancer incidence and cancer mortality: disparate relationships by race.
Authors: Davidovics Sarah A. , Prizment Anna , Visvanathan Kumar , Visvanathan Kala 
Published: August 2014

Studies have demonstrated an association between elevated levels of total white blood cell (WBC) count, within the clinically normal range, and an increased risk of overall cancer incidence and mortality. However, a paucity of data exists on the relationship between WBC subtypes and cancer outcomes. We hypothesize that chronic low-grade inflammation in healthy individuals, reflected by elevated neutrophil count, is associated with an increased risk of subsequent cancer incidence and mortality.

To test this hypothesis, we prospectively evaluated the association between neutrophil count, cancer incidence, and mortality in the Atherosclerosis Risk in Communities (ARIC) study. Total neutrophil counts were measured at enrollment (1987-1989) and, in a subset, at visit 2. Participants with a neutrophil count more than two standard deviations from the mean and cancer at baseline were excluded. Cancer incidence and mortality data were available through 12/31/2006 and 12/31/2009, respectively. Hazard ratios (HR) and 95% confidence intervals (CI) were estimated using Cox proportional hazards models. Neutrophil count was modeled as tertiles, with separate cut-offs for whites and blacks to account for differences in their distribution.

The analytic cohort consisted of 6,252 whites (51% female) and 3,400 blacks (62% female). The mean age at blood draw was 54 years and 53.5 years, respectively. The mean neutrophil count was 3.7 cu/mcL (range: 1.9-6.6) in whites and 2.7 cu/mcL (range: 1.0-5.7) in blacks. Among whites, 1,346 cancer cases developed over 102,541 person-years and, among blacks, 655 cancer cases developed over 53,308 person-years. In analyses of cancer mortality, 504 cancer deaths occurred over 125,744 person-years in whites and 301 over 63,592 person-years in blacks. The proportion of cancer subtypes did not differ by race for either outcome. Neutrophil count was not associated with cancer incidence in whites or blacks. However, in blacks, neutrophil count was associated with a significant but non-linear increase in cancer mortality in the highest tertile compared to the lowest (HR: 1.4, 95% CI: 1.0, 1.8) after adjusting for study center, age, sex, education level, body mass index, prior cardiovascular disease, diabetes, smoking, alcohol intake and aspirin use in the past two weeks. This association was modified by smoking status (p-interaction=0.04). Among never smokers, a linear increase in mortality was observed with a 2.1-fold (95% CI: 1.1, 3.7) increase in risk in the highest versus lowest tertile. This association remained when the average neutrophil count (baseline and visit 2) was used. A similar pattern was not observed in whites.

Neutrophil count measured prior to diagnosis was associated with cancer mortality among non-smokers in blacks but not whites. This supports a relationship between chronic low-grade inflammation and cancer outcomes in blacks, the mechanism of which remains to be elucidated.

Citation Format: Sarah A. Davidovics, Anna Prizment, Kumar Visvanathan, Kala Visvanathan. Neutrophil count, cancer incidence and cancer mortality: disparate relationships by race. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2525. doi:10.1158/1538-7445.AM2013-2525