Purpose: To examine associations of pre-diagnosis high-sensitivity C-reactive (hsCRP) with breast cancer incidence and post-diagnosis survival and to assess whether associations are modified by Body Mass Index (BMI). Methods: A prospective analysis of the Women's Health Initiative was conducted among 17,841 cancer free postmenopausal women with baseline hsCRP measurements. Cox proportional hazards models were used to examine associations between hsCRP concentrations and: 1) breast cancer risk (n cases=1,114) and 2) all-cause mortality after breast cancer diagnosis. Hazard ratios are per 1 standard deviation in log hsCRP. Results: hsCRP was not associated with breast cancer risk overall (HR =1.05; 95% CI, 0.98, 1.12); however, an interaction between BMI and hsCRP was observed (p-interaction=0.02). A 1 SD increase in log hsCRP was associated with 17% increased breast cancer risk (HR=1.17, 95% CI=1.03, 1.33) among lean women (BMI<25), whereas no association was observed among overweight/obese (BMI≥25) women. Pre-diagnosis hsCRP was not associated with overall mortality (HR=1.04; 95% CI=0.88, 1.21) after breast cancer diagnosis; however, an increased mortality risk was apparent among leaner women with higher hsCRP levels (HR=1.39, 95% CI= 1.03, 1.88). Conclusion: Pre-diagnosis hsCRP levels are not associated with postmenopausal breast cancer incidence or survival overall; however, increased risks are suggested among leaner women. The observed effect modification is in the opposite direction of a previous case-control study finding and warrants further investigation. Impact: Associations of higher CRP levels with incident breast cancer and survival after breast cancer may depend on BMI.
- Received December 12, 2016.
- Revision received March 3, 2017.
- Accepted March 6, 2017.
- Copyright ©2017, American Association for Cancer Research.