Non-malignant drivers of elevated C-reactive protein levels differ in patients with and without a history of cancer.

PURPOSE: Elevations in C-reactive protein (CRP) levels predict metastasis and mortality in a number of malignancies. However, the impact of non-malignant factors on CRP levels in patients with cancer remains unknown. To address this issue, we conducted an investigation of the National Social Life, Health, and Aging Project (NSHAP) cohort.
METHODS: NSHAP participants with a history of malignancy were included. The 222-participant cohort was subdivided by CRP levels into low-risk (CRP <3 mg/L) and high-risk (CRP ≥3 mg/L) groups. Univariate and multivariate binary logistic regression analyses examined the impact of variables spanning social factors, demographic characteristics, and past medical history on high-risk CRP levels.
RESULTS: Of the cohort, 42.3% exhibited high-risk CRP levels. These participants were more likely to be unmarried (p = 0.013), to be a racial/ethnic minority (p = 0.012), to not use HMG-CoA reductase inhibitor (statin) medications (p = 0.032), and to be obese (p = 0.002). On multivariate logistic regression analysis, these variables were also significant predictors of high-risk CRP levels. For example, compared with participants who had a normal body mass index (BMI), obese participants were nearly 5 times more likely (odds ratio 5.725; 95% CI 1.848, 12.079; p = 0.001) to exhibit high-risk CRP levels.
CONCLUSIONS: CRP remains an important prognostic biomarker in the management of known malignancies. However, patients with a known history of cancer can also exhibit elevated CRP levels due to non-malignant factors such as race and ethnicity, statin use, marital status, and BMI. Consequently, further studies are needed to assess the predictive potential of CRP levels for cancer prognostication in the face of these social and biologic variables before use of this biomarker is widely adopted in clinical practice.