Calcium plus vitamin D supplementation and the risk of colorectal cancer.
- J. Wactawski‐Wende
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- J. Kotchen
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- G. Anderson
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- A. Assaf
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- A. Assaf
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- R. Brunner
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- M. O'sullivan
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- K. Margolis
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- J. Ockene
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- L. Phillips
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- L. Pottern
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- R. Prentice
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- J. Robbins
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- T. Rohan
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- G. Sarto
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- S. Sharma
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- M. Stefanick
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- L. Horn
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- R. Wallace
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- E. Whitlock
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- T. Bassford
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- S. Beresford
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- H. Black
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- D. Bonds
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- R. Brzyski
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- B. Caan
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- R. Chlebowski
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- B. Cochrane
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- C. Garland
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- M. Gass
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- J. Hays
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- G. Heiss
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- S. Hendrix
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- B. Howard
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- J. Hsia
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- F. Hubbell
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- R. Jackson
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- K. Johnson
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- H. Judd
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- C. Kooperberg
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- L. Kuller
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- A. LaCroix
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- D. Lane
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- R. Langer
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- N. Lasser
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- C. Lewis
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- M. Limacher
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- J. Manson
Enhanced Details
Abstract
BACKGROUND Higher intake of calcium and vitamin D has been associated with a reduced risk of colorectal cancer in epidemiologic studies and polyp recurrence in polyp-prevention trials. However, randomized-trial evidence that calcium with vitamin D su...
BACKGROUND Higher intake of calcium and vitamin D has been associated with a reduced risk of colorectal cancer in epidemiologic studies and polyp recurrence in polyp-prevention trials. However, randomized-trial evidence that calcium with vitamin D supplementation is beneficial in the primary prevention of colorectal cancer is lacking. METHODS We conducted a randomized, double-blind, placebo-controlled trial involving 36,282 postmenopausal women from 40 Women's Health Initiative centers: 18,176 women received 500 mg of elemental calcium as calcium carbonate with 200 IU of vitamin D3 [corrected] twice daily (1000 mg of elemental calcium and 400 IU of vitamin D3) and 18,106 received a matching placebo for an average of 7.0 years. The incidence of pathologically confirmed colorectal cancer was the designated secondary outcome. Baseline levels of serum 25-hydroxyvitamin D were assessed in a nested case-control study. RESULTS The incidence of invasive colorectal cancer did not differ significantly between women assigned to calcium plus vitamin D supplementation and those assigned to placebo (168 and 154 cases; hazard ratio, 1.08; 95 percent confidence interval, 0.86 to 1.34; P=0.51), and the tumor characteristics were similar in the two groups. The frequency of colorectal-cancer screening and abdominal symptoms was similar in the two groups. There were no significant treatment interactions with baseline characteristics. CONCLUSIONS Daily supplementation of calcium with vitamin D for seven years had no effect on the incidence of colorectal cancer among postmenopausal women. The long latency associated with the development of colorectal cancer, along with the seven-year duration of the trial, may have contributed to this null finding. Ongoing follow-up will assess the longer-term effect of this intervention. (ClinicalTrials.gov number, NCT00000611.).