Table 4.

Age-adjusted relative risk of colorectal cancer by subsite for quintiles of dietary calcium and total calcium (dietary calcium plus calcium from supplements)

Quintile of calcium intake
Q1Q2Q3Q4Q5Ptrend
Rectum (74 cases)
    Dietary calcium*
        Range of intake (mg)<412412-528529-655656-830>830
        RR (95% CI)1.00 (reference)0.73 (0.35-1.55)1.02 (0.51-2.01)0.82 (0.40-1.69)0.87 (0.43-1.77)0.85
    Total calcium
        Range of intake (mg)<472472-635636-844845-1,270>1,270
        RR (95% CI)1.00 (reference)1.19 (0.57-2.48)1.10 (0.52-2.32)1.23 (0.60-2.53)0.93 (0.43-2.01)0.30
Colon (284 cases)
    Dietary calcium*
        Range of intake (mg)<412412-528529-655656-830>830
        RR (95% CI)1.00 (reference)0.78 (0.56-1.11)0.66 (0.46-0.94)0.70 (0.49-0.99)0.62 (0.43-0.90)0.02
    Total calcium
        Range of intake (mg)<472472-635636-844845-1,270>1,270
        RR (95% CI)1.00 (reference)0.84 (0.59-1.18)0.66 (0.46-0.96)0.78 (0.55-1.11)0.69 (0.48-0.99)0.10
Distal colon (112 cases)
    Dietary calcium*
        Range of intake (mg)<412412-528529-655656-830>830
        RR (95% CI)1.00 (reference)0.64 (0.36-1.14)0.70 (0.40-1.23)0.76 (0.44-1.31)0.66 (0.37-1.16)0.54
    Total calcium
        Range of intake (mg)<472472-635636-844845-1,270>1,270
        RR (95% CI)1.00 (reference)0.76 (0.43-1.34)0.86 (0.49-1.49)0.71 (0.40-1.26)0.71 (0.40-1.26)0.26
Proximal colon (172 cases)
    Dietary calcium*
        Range of intake (mg)<412412-528529-655656-830>830
        RR (95% CI)1.00 (reference)0.88 (0.57-1.35)0.63 (0.39-1.01)0.65 (0.41-1.04)0.60 (0.38-0.97)0.01
    Total calcium
        Range of intake (mg)<472472-635636-844845-1,270>1,270
        RR (95% CI).00 (reference)0.89 (0.57-1.38)0.54 (0.33-0.90)0.83 (0.53-1.29)0.68 (0.42-1.08)0.24
  • * Based on residual method for energy adjustment of dietary calcium intake.

  • Based on residual method for energy adjustment of dietary calcium intake plus unadjusted supplemental calcium intake.