STUDY | DETAILS OF STUDY | RESULTS | LEVEL OF EVIDENCE |
---|---|---|---|
Dalberg et al,43 1999 | Retrospective study of 242 cases of CRC | People living in the Faroe Islands have one of the lowest incidence rates of CRC in northwestern Europe and North America despite a diet low in vegetables and high in fat | II |
Marcus and Newcomb,44 1998 | Case-control study: 348 cases of colon cancer and 164 cases of rectal cancer were compared with 678 controls | Calcium intake tended to lower risk of both cancers when fifth to first quintiles were compared (OR 0.6, 95% CI 0.4–1.0 for rectal cancer; OR 0.6, 95% CI 0.3–1.1 for colon cancer); intake of vitamin D showed a similar, but nonsignificant, trend | II |
Franceschi and Favero,45 1999 | Case-control study: 1953 cases of CRC were compared with 5155 controls | Intake of calcium was inversely associated with risk of CRC | II |
Levi et al,46 2000 | Case-control study: 223 men and women with CRC were compared with 491 controls | No significant associations between intake of calcium or vitamin D and risk of CRC | II |
Pritchard et al,47 1996 | Case-control study: 352 colon cancer cases and 217 rectal cancer cases were compared with 512 controls | Highest vs lowest quartile of vitamin D intake was inversely associated with risk of CRC (stronger association with rectal cancer than with colon cancer); calcium intake was not associated with risk of CRC at either cancer site | II |
De Stefani et al,48 1997 | Case-control study: 282 patients with adenocarcinomas were compared with 564 controls | Comparison of highest to lowest quartile of calcium intake showed reduced risk of CRC (OR 0.41, 95% CI 0.24–0.69); effect of calcium was greatest at low levels of fat intake | II |
Boutron et al,49 1996 | Case-control study: 154 patients with small (< 10 mm) adenomas, 208 with large adenomas, and 171 with CRC were compared with 426 polyp-free controls and 309 other controls | No consistent results | II |
McCullough et al,50 2003 | Prospective cohort study of 68 866 men and 66 883 women found CRC in 421 men and 262 women | Total calcium intake was associated with marginally lower risk of CRC in men and women (RR 0.87, 95% CI 0.67–1.12); strongest association with calcium from supplements (RR 0.69, 95% CI 0.49–0.96 for ≥500 mg/d vs none); total vitamin D intake associated with reduced risk of CRC only in men (RR 0.71, 95% CI 0.51–0.98) | II |
Terry et al,51 2002 | Prospective cohort study of 61 463 women found 572 cases of CRC | Women with high calcium intake (median 914 mg/d) had a lower risk of CRC compared with women with low intake (486 mg/d) (rate ratio 0.72, 95% CI 0.56–0.93); vitamin D was not associated with risk | II |
Pietinen et al,52 1999 | Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study of 27 111 male Finnish smokers found 185 cases of CRC | Calcium had a modest effect on risk of CRC (RR 0.6, 95% CI 0.4–0.9) | II |
Martinez et al,53 1996 | Nurses Health Study of 89 448 nurses found 501 cases of CRC | Inverse association suggested between total vitamin D intake and CRC; highest vs lowest intake comparison was significant among subjects who reported high or low intake consistently across all 3 questionnaires (RR 0.70, 95% CI 0.16–0.70) | II |
Kampman et al,54 1994 | Netherlands Cohort Study of 120 852 men and women found 326 cases of CRC | No substantially decreased risk of CRC | II |
Jarvinen et al,55 2001 | Prospective cohort study of 9959 men and women | No significant results for calcium or vitamin D | II |
Kato et al,56 1997 | New York University Women’s Health Study of 14 727 found 100 cases of CRC | In an association explained mainly by calcium content, increased intake of fish and shellfish was associated with a lower risk of CRC (RR 0.49, 95% CI 0.27–0.89); similar results obtained for intake of dairy products | II |
Van Gorkom et al,57 2002 | 111 patients with sporadic adenomas were treated with 2 placebos, 1 g calcium plus placebo, or resistant starch plus placebo | No effect on increased epithelial cell proliferation (intermediate risk marker for CRC) | II |
Cascinu et al,58 2000 | 34 CRC post-surgery patients were given 2 g of calcium and vitamins A, C, and E or placebo | No effect on colorectal cell proliferation | II |
Cats et al,59 1995 | 15 patients at increased risk of hereditary nonpolyposis CRC were treated with 1.5 g calcium as calcium carbonate for 12 wk; 15 others were given placebo | No significant reduction in epithelial cell proliferation | II |
Hofstad et al,60 1998 | 116 polyp-bearing patients received a mixed supplement containing 1.6 g of calcium as calcium carbonate for 3 y | No overall effect on polyp growth | II |
Baron et al,61 1999 | 930 subjects with colorectal adenomas were given 1200 mg of elemental calcium (3 g of calcium carbonate) | Moderate reduction in adenoma recurrence with calcium supplementation (RR 0.85, 95% CI 0.74–0.98) | I |
Grau et al,62 2003 | 803 subjects | When vitamin D intake was above the median, calcium supplementation lowered risk of adenoma recurrence (RR 0.71, 95% CI 0.57–0.89); vitamin D had a significant effect on adenoma recurrence only when combined with calcium supplementation | I |
CRC—colorectal cancer, CI—confidence interval, OR—odds ratio, RR—relative risk.