White Blood Cell Count, Neutrophil-to-Lymphocyte Ratio, and Incident Cancer in the UK Biobank.

BACKGROUND

The peripheral white blood cell (WBC) and neutrophil-to-lymphocyte ratio (NLR) reflect levels of inflammation and adaptive immunity. They are associated with cancer prognosis, but their associations with cancer incidence are not established.

METHODS

We evaluated 443,540 cancer-free adults in the UK Biobank with data on total WBC and its subsets, follow-up starting one year after baseline. Cox regression was used to estimate hazard ratios (HR) per quartile of WBC or NLR for incidence of 73 cancer types.

RESULTS

22,747 incident cancers were diagnosed during a median of 6.9 years of follow-up. WBC was associated with risk of cancer overall [HR, 1.05; 95% confidence interval (CI), 1.03-1.06], chronic lymphocytic leukemia/small lymphocytic leukemia (CLL/SLL, 2.79; 95% CI, 2.45-3.18), lung cancer (1.14, 95% CI, 1.08-1.20), and breast cancer (95% CI, 1.05-1.02-1.08). NLR was positively associated with cancer overall (HR, 1.03; 95% CI, 1.02-1.04, per quartile) and kidney cancer (1.16; 95% CI, 1.07-1.25), and inversely with CLL/SLL (0.38; 95% CI, 0.33-0.42).

CONCLUSIONS

High WBC or NLR may reflect excessive inflammatory status, promoting development of some cancers. Conversely, low NLR indicates a relative rise in lymphocytes, which could reflect an increase in circulating premalignant cells before CLL/SLL diagnosis. Peripheral WBC and NLR, in combination with other clinical information or biomarkers, may be useful tools for cancer risk stratification.

IMPACT

Elevated levels of WBCs or an increased NLR may indicate an overly active inflammatory response, potentially contributing to the eventual onset of certain types of cancer.