Inflammation and the immune system have been linked to cancer pathogenesis. Prospective studies relating inflammatory biomarkers to cancer incidence and death have yielded mixed results.
A prospective cohort study involving 143,748 postmenopausal women aged 50 to 79 years who were free of cancer at baseline and were enrolled in the Women’s Health Initiative was conducted at 40 US clinical centers to determine whether there is an independent association of white blood cell (WBC) count with incident cancer in postmenopausal women. Invasive breast, colorectal, endometrial, and lung cancer were the primary outcome measures.
There was a graded correlation of WBC count with the incidence of all four forms of cancer in multivariate models. Compared to women with a WBC count in the lowest quartile (2.50-4.79×109 cells/L), those with a WBC count in the upper quartile (6.80-15.00×109 cells/L) had a statistically significantly higher risk of invasive breast cancer (hazard ratio [HR], 1.15; 95% confidence interval [CI], 1.04-1.26), colorectal cancer (HR, 1.19; 95% CI, 1.00-1.41), endometrial cancer (HR, 1.42; 95% CI, 1.12-1.79), and lung cancer (HR, 1.63; 95% CI, 1.35-1.97). When malignancies that developed within the first two years of follow-up were eliminated, the results were identical. When the results were confined to nonsmokers, statistically significant correlations for invasive breast cancer and endometrial cancer persisted. The WBC count was also linked to breast cancer, lung cancer, and total cancer mortality in statistically meaningful ways.