Raloxifene and colorectal cancer.
OBJECTIVE
To determine the effect of raloxifene on colorectal cancer (CRC) risk.


METHODS
We analyzed data from the Multiple Outcomes of Raloxifene Evaluation (MORE) trial, a randomized, blinded clinical trial designed to determine the effect of raloxifene on vertebral fracture risk. In this trial, 7705 women received either raloxifene or placebo and were followed for an average of 3.4 years. CRC cases were classified as definite (pathology available), probable (imaging or colonoscopic diagnosis), or possible (self-report). Relative hazard for CRC was calculated using multivariate Cox proportional hazards models.


RESULTS
Fifty cases of definite or probable CRC were diagnosed; 40 were definite and 10 probable. Twenty-nine cases occurred among the 5129 women in the raloxifene group, and 21 occurred among the 2576 women in the placebo group (p = 0.15). The relative hazard for CRC for women treated with raloxifene was 0.78 (95% CI 0.43, 1.43, p = 0.43). Restricting the analysis to definite CRC, the relative hazard was 0.77 (95% CI 0.39, 1.5, p = 0.45).


CONCLUSIONS
Although the MORE trial was large, the number of CRC cases was too small to provide definitive evidence concerning the effect of raloxifene on CRC risk. There does not appear to be a substantial increased risk of CRC with raloxifene use. Studies including larger numbers of women and women at risk for CRC should further investigate the effect of raloxifene on CRC.
Walsh
Judith M E
JM
Division of General Internal Medicine, University of California, San Francisco, USA. jwalsh@medicine.ucsf.edu
Cheung
Angela M
AM
Yang
Donald
D
Litwack
Stephanie
S
Grady
Deborah
D
D000368:Aged; D015519:Bone Density / Q000187:drug effects; D015179:Colorectal Neoplasms / Q000139:chemically induced* / Q000453:epidemiology / Q000517:prevention & control; D004311:Double-Blind Method; D020847:Estrogen Receptor Modulators / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D006801:Humans; D008875:Middle Aged; D015663:Osteoporosis, Postmenopausal / Q000150:complications / Q000188:drug therapy*; D016016:Proportional Hazards Models; D020849:Raloxifene Hydrochloride / Q000008:administration & dosage / Q000494:pharmacology*; D012307:Risk Factors; D020845:Selective Estrogen Receptor Modulators / Q000008:administration & dosage / Q000494:pharmacology*; D016103:Spinal Fractures / Q000209:etiology / Q000517:prevention & control; D013997:Time Factors; D014481:United States / Q000453:epidemiology
D020847:Estrogen Receptor Modulators; D020845:Selective Estrogen Receptor Modulators; D020849:Raloxifene Hydrochloride