C-reactive protein levels are not associated with increased risk for colorectal cancer in women.
BACKGROUND
Observations that risk for colorectal cancer is elevated in patients with inflammatory bowel disease and that long-term use of anti-inflammatory drugs may reduce colorectal cancer risk have raised the possibility that inflammation may play a role in the development of colorectal cancer. While a recent prospective study observed a positive association between C-reactive protein (CRP), a marker of inflammation, and risk for colon cancer, data testing this hypothesis are sparse.


OBJECTIVE
To evaluate whether plasma CRP levels predict colorectal cancer risk in women.


METHODS
Prospective cohort study, with 97% morbidity follow-up and 100% mortality follow-up within the past 2 years.


METHODS
Women's Health Study.


METHODS
27,913 apparently healthy women age 45 years or older who had CRP measured at entry into a trial of low-dose aspirin and vitamin E. Maximum length of intervention and follow-up was 10.8 years.


METHODS
Self-reported incident colorectal adenocarcinoma confirmed by medical record review.


RESULTS
169 women developed colorectal adenocarcinomas during follow-up. Baseline CRP levels were not significantly associated with colorectal cancer risk. The multivariate hazard ratios according to cutoff points for CRP proposed in clinical guidelines were 0.79 (95% CI, 0.53 to 1.17) for the category of 1 to 3 mg/L and 0.66 (CI, 0.43 to 1.03) for the category of greater than 3 mg/L (P for trend = 0.09), as compared with the category of less than 1 mg/L. High CRP levels were also not associated with increased risk in analyses done according to tumor location and stage at diagnosis, according to alternative cutoff points for CRP, or in any of the subgroups evaluated.


CONCLUSIONS
Despite multivariate analysis, residual confounding might still be present. Although this study was prospective, we cannot completely exclude undetected cancer at baseline. Measurements for CRP were available for only 71% of women in the cohort; however, the women who did and those who did not provide blood were mostly similar.


CONCLUSIONS
Plasma CRP levels do not appear to predict an increased risk for developing colorectal cancer in apparently healthy women. Low-grade inflammation may not play an important role in increasing the risk for colorectal cancer.
Zhang
Shumin M
SM
Brigham and Women's Hospital, Harvard Medical School, and Harvard School of Public Health, Boston, Massachusetts.
Buring
Julie E
JE
Lee
I-Min
IM
Cook
Nancy R
NR
Ridker
Paul M
PM
D000230:Adenocarcinoma / Q000097:blood* / Q000209:etiology*; D015415:Biomarkers / Q000097:blood; D002097:C-Reactive Protein / Q000378:metabolism*; D015179:Colorectal Neoplasms / Q000097:blood* / Q000209:etiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008875:Middle Aged; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012307:Risk Factors
D015415:Biomarkers; D002097:C-Reactive Protein