Calcium intake and colorectal adenoma risk: Dose‐response meta‐analysis of prospective observational studies. Issue 7 (4th September 2014)

• Record Type: Journal Article
• Authors: Keum, NaNa; Lee, Dong Hoon; Greenwood, Darren C.; Zhang, Xuehong; Giovannucci, Edward L.
• Is Part Of: International journal of cancer. Volume 136:Issue 7(2015:Apr. 01)
• Page Start: 1680
• Page End: 1687
• Publication Date: 2014-09-04
• Subjects: Cancer -- Periodicals; Cancer -- Prevention -- Periodicals; 616.994
• DOI: 10.1002/ijc.29164
• Languages: English
• ISSNs: 0020-7136

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <p>Evidence from randomized controlled trials suggests that calcium may protect against recurrence of colorectal adenomas, which could lead to the subsequent prevention of cancer. Yet the trials used only a large single dose and were of small sizes, and thus, knowledge of the dose‐response relationship and influence on high‐risk adenomas is limited. To address these issues, we conducted linear and nonlinear dose‐response meta‐analyses primarily based on prospective observational studies published up to July 2014 identified from PubMed and Embase. Summary relative risks (RRs) and 95% confidence intervals (CIs) were calculated for total and supplemental calcium intake, respectively, using a random‐effects model. For total calcium intake, summary RR for each 300 mg/day increase was 0.95 (95% CI = 0.92–0.98; <italic>I</italic><sup>2</sup> = 45%; eight studies with 11, 005 cases; range of intake = 333–2, 229 mg/day). Evidence of nonlinearity was indicated: <bold>approximately, compared to 550 mg/day of total calcium intake, the summary RR was 0.92 (95% CI = 0.89–0.94) at 1, 000 mg/day and 0.87 (95% CI = 0.84–0.90) at 1, 450 mg/day (<italic>p</italic><sub>nonlinearity</sub></bold> < <bold>0.01). Associations were stronger for high‐risk adenomas (≥1 cm in diameter, (tubulo)villous histology, dysplasia, or multiplicity): approximately, compared to 550 mg/day of total calcium intake, the summary RR was 0.77 (95% CI = 0.74–0.81) at 1, 000 mg/day and reduced to 0.69 (95% CI = 0.66–0.73) at 1, 450 mg/da (<italic>p</italic><sub>nonlinearity</sub></bold> < <bold>0.01). For supplemental calcium intake, summary RR of total adenoma risk for each 300 mg/day increase was 0.96 (95% CI = 0.93–0.99; <italic>I</italic><sup>2</sup> = 0%; three studies with 4, 548 cases; range of supplementation = 0–1, 366 mg/day). In conclusion, calcium intake may continue to decrease the risk of adenomas, particularly high‐risk adenomas, over a wide range of calcium intake.</bold></p> </abstract>