Chemoprevention of colon cancer: metaanalysis & systematic review of preclinical studies in rats & mice
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Meta-Analysis of Chemoprevention Studies with Calcium
in Carcinogen-Initiated Rats and in Min Mice.
Figures from Rat Data Tables
Identical figures below as above, but "Text links" instead of "Icon links"
- Calcium / Rats figure shows the potency of all calcium salts on the incidence of colonic tumors in rats (all studies except excluded refs)
- Calcium studies Funnel plot of (it shows no clear publication bias)
- Subset analysis of only Calcium lactate studies in rats
- Subset analysis of ALL but Lactate studies, Calcium phosphate, carbonate and gluconate
- Subset analysis of calcium studies in rats fed a High Fat diet
- Subset analysis of calcium studies in rats fed a Low Fat diet
- Meta-Analysis shareware EasyMA (DOS 2001 version) was used to analyse rat data and draw figures
- Only one Calcium study in Apc mutated mice (Huerta et al., 2003): No need to do a meta-analysis, no figure. See data on [Min mice Table]
An Explanation of Data Presented Above
Calcium effect in carcinogen-injected rats. The meta-analysis of 17 publications including 1732 rats showed that calcium reduces colon tumour incidence in rats: RR= 0.91 (p=0.03) [Table], with similar RR with Random model (0.92, p=0.06) [Figure]. The hypothesis that calcium specifically reduces high-fat diet promotion was tested by analysing separately studies with high fat (>20% fat, w/w) and low fat diets (< 6%), but both subsets yielded similar RRs 0.93 & 0.92, and p values (see figures: High Fat & Low Fat). Also, we tested the hypothesis that some calcium salts were more protective than others. This was indeed the case: calcium lactate was protective in rats (RR=0.7, p=0.02, Figure), but phosphate, carbonate and gluconate afforded no protection (RR=1, Figure).
Calcium effect in mutated mice. Small intestinal polyp yield increases by +9 and +21% when dietary calcium doubles (79 mice: 2 lines on top of [Table]. Calcium did not reduce the number of colonic polyps either . In contrast, mice fed the high-calcium AIN76 diet had fewer polyps than mice fed the low-calcium Western diet designed by Newmark . This polyp reduction to 37% of control value (weighted mean, p<0.001) cannot however be attributed to calcium alone, since diets also differed for phosphate, fat, and vitamin D content (6 lines at bottom of [Table]).
Text extracted from the article: "Corpet D.E. & Pierre F., 2005, European Journal of Cancer, How good are Rodent Models of Carcinogenesis in Predicting Efficacy in Humans? Systematic Review and Meta-Analysis of Colon Tumour Chemoprevention in Rats, Mice and Men. in the press." Fetch the [preprint] (.pdf)
Abbreviations /Data Tables
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- Column "p": NS, Non Significant; MS, Marginally Significant; *, significant: p<0.05 (by Fisher's test).
Last line: Meta-analysis global p value, calculated by Chi-square test, without Yates correction for continuity.
- Columns 3 & 4: Number of tumor-bearing rats in control group (col.3); Total number of control rats (col.4). Control rats' data were duplicated in each line with treated rats data, although control rats were summed only once in last line. Duplicated numbers are tagged with a "-" (e.g., 15- )
- Meta-Analysis Methods, Rats:
See bottom of previous page on Meta Analysis
DE Corpet & F Pierre, 2005, European J. Cancer
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