Background: Serum C-reactive protein (CRP) is a marker of acute inflammatory response and has been associated with health outcomes in some studies. Inflammation and immune response may have potential prognostic implications for breast cancer survivors.
Methods: The Women's Healthy Eating and Living Study includes 2,919 early-stage breast cancer survivors with serum collected 2 years postdiagnosis and follow-up for clinical outcomes over approximately 7 years. CRP concentrations were measured using high-sensitivity electrochemiluminescence assay. Outcomes, including all-cause mortality, breast cancer-specific mortality, and additional breast cancer events were oncologist verified from medical records and death certificates. Cox proportional hazards models were conducted with adjustment for potential confounding factors to generate HRs and 95% confidence intervals (CI).
Results: CRP concentrations in women diagnosed with breast cancer were associated with death due to any cause, death due to breast cancer, and additional breast cancer events, after adjustment for sociodemographic and cancer characteristics (lnCRP: P < 0.05 for all three outcomes). The HR for women with (vs. without) acute inflammation suggests a threshold effect on overall survival, rather than a dose-response relationship (≥ 10.0 mg/L vs. <1 mg/L: HR, 1.96; 95% CI, 1.22-3.13). Associations were similar for breast cancer-specific mortality (HR, 1.91; 95% CI, 1.13-3.23) and any additional breast cancer-related event (HR, 1.69; 95% CI, 1.17-2.43).
Conclusions: Acute inflammation status (CRP ≥ 10 mg/L) may be an important independent biomarker for long-term survival in breast cancer survivors.
Impact: Interventions to decrease circulating CRP concentrations in breast cancer survivors with acute inflammation may improve prognosis.