Purpose: We tested the hypothesis that baseline plasma levels of C-reactive protein (CRP) are associated with risk of incident cancer in the general population and early death in patients with cancer.

Patients and Methods: A total of 10,408 individuals from the Danish general population who had CRP measured at baseline were observed for up to 16 years; 1,624 developed cancer, and of these, 998 patients died during follow-up. Follow-up was 100% complete. We excluded individuals with a cancer diagnosis at baseline.

Results: Baseline CRP levels more than 3 versus less than 1 mg/L were associated with multifactorially adjusted hazard ratios of 1.3 (95% CI, 1.0 to 1.6) for cancer of any type, 2.2 (95% CI, 1.0 to 4.6) for lung cancer, 1.9 (95% CI, 0.8 to 4.6) for colorectal cancer, and 0.7 (95% CI, 0.4 to 1.4) for breast cancer. Corresponding hazard ratios for the highest versus the lowest quintile of baseline CRP levels were 1.3 (95% CI, 1.0 to 1.6), 2.1 (95% CI, 1.2 to 3.8), 1.7 (95% CI, 0.8 to 3.2), and 0.9 (95% CI, 0.5 to 1.7), respectively. Multifactorially adjusted hazard ratios for early death in patients with cancer were 1.8 (95% CI, 1.2 to 2.7) for CRP more than 3 versus less than 1 mg/L and 1.4 (95% CI, 1.1 to 1.7) for the highest versus the lowest quintile. Elevated CRP levels were associated with early death in patients with cancer having localized disease, but not in those with metastases (interaction; P = .03).

Conclusion: Elevated levels of CRP in cancer-free individuals are associated with increased risk of cancer of any type, of lung cancer, and possibly of colorectal cancer. Moreover, elevated levels of baseline CRP associate with early death after a diagnosis of any cancer, particularly in patients without metastases.