Table 2.

Multivariable^* relative risk of colorectal cancer according to total calcium intake in the Nurses’ Health Study (1980–2012) and Health Professionals Follow-up Study (1986–2012)

	Total calcium intake (mg/d)						P-trend
	<600	600–<800	800–<1000	1000–<1200	1200–<1400	≥1400
Colorectal cancer
NHS
No.cases (n=1,828)	313	459	397	306	187	166
Age-adjusted	1 (ref)	0.96 (0.83, 1.11)	0.81 (0.69, 0.94)	0.75 (0.63, 0.88)	0.67 (0.56, 0.81)	0.57 (0.47, 0.69)	<0.001
MVRR	1 (ref)	1.00 (0.86, 1.16)	0.87 (0.74, 1.02)	0.85 (0.71, 1.01)	0.80 (0.65, 0.97)	0.72 (0.58, 0.90)	0.01
HPFS
No.cases (n=1,250)	201	358	270	187	112	122
Age-adjusted	1 (ref)	0.91 (0.76, 1.09)	0.78 (0.65, 0.94)	0.83 (0.67, 1.01)	0.79 (0.63, 1.00)	0.74 (0.59, 0.92)	0.01
MVRR	1 (ref)	1.00 (0.84, 1.20)	0.93 (0.76, 1.13)	1.04 (0.84, 1.28)	1.01 (0.79, 1.29)	0.98 (0.76, 1.25)	0.89
Pooled
No.cases (n=3,078)	514	817	667	493	299	288
Age-adjusted	1 (ref)	0.94 (0.84, 1.05)	0.80 (0.71, 0.89)	0.78 (0.68, 0.88)	0.72 (0.61, 0.84)	0.64 (0.50, 0.83)	0.01
MVRR	1 (ref)	1.00 (0.89, 1.12)	0.89 (0.79, 1.01)	0.93 (0.76, 1.13)	0.89 (0.70, 1.12)	0.83 (0.62, 1.12) **	0.36
Colon cancer
NHS
No.cases (n=1,427)	236	361	308	243	144	135
MVRR	1 (ref)	1.02 (0.86, 1.21)	0.86 (0.71, 1.04)	0.85 (0.70, 1.05)	0.79 (0.62, 1.00)	0.75 (0.59, 0.97)	0.02
HPFS
No.cases (n=996)	162	292	212	152	94	84
MVRR	1 (ref)	1.00 (0.82, 1.22)	0.89 (0.71, 1.10)	1.02 (0.81, 1.30)	1.04 (0.79, 1.36)	0.82 (0.62, 1.09)	0.43
Pooled
No.cases(n=2,423)	398	653	530	395	238	219
MVRR	1 (ref)	1.01 (0.89, 1.15)	0.87 (0.76, 1.00)	0.92 (0.78, 1.10)	0.90 (0.68, 1.17)	0.78 (0.65, 0.95) **	0.05
Proximal colon cancer
NHS
No.cases (n=856)	114	201	201	155	92	93
MVRR	1 (ref)	1.13 (0.89, 1.44)	1.12 (0.87, 1.44)	1.08 (0.82, 1.42)	0.97 (0.71, 1.33)	1.00 (0.72, 1.38)	0.89
HPFS
No.cases (n=426)	59	129	99	62	43	34
MVRR	1 (ref)	1.14 (0.83, 1.57)	1.05 (0.74, 1.48)	1.00 (0.68, 1.47)	1.16 (0.76, 1.77)	0.83 (0.53, 1.31)	0.47
Pooled
No.cases(n=1,282)	173	330	300	217	135	127
MVRR	1 (ref)	1.14 (0.94, 1.37)	1.09 (0.89, 1.34)	1.05 (0.84, 1.32)	1.03 (0.80, 1.33)	0.94 (0.72, 1.22)	0.57
Distal colon cancer
NHS
No.cases (n=528)	112	147	103	80	48	38
MVRR	1 (ref)	0.92 (0.71, 1.19)	0.65 (0.48, 0.87)	0.65 (0.47, 0.91)	0.65 (0.44, 0.95)	0.53 (0.35, 0.82)	<0.001
HPFS
No.cases (n=364)	70	107	67	54	33	33
MVRR	1 (ref)	0.91 (0.66, 1.24)	0.70 (0.49, 1.01)	1.00 (0.68, 1.47)	0.97 (0.63, 1.51)	0.81 (0.52, 1.28)	0.79
Pooled
No.cases(n=892)	182	254	170	134	81	71
MVRR	1 (ref)	0.91 (0.75, 1.11)	0.67 (0.53, 0.84)	0.80 (0.52, 1.22)	0.78 (0.52, 1.17)	0.65 (0.43, 0.99) **	0.25
Rectal cancer
NHS
No.cases (n=401)	77	98	89	63	43	31
MVRR	1 (ref)	0.90 (0.66, 1.23)	0.90 (0.64, 1.25)	0.84 (0.58, 1.24)	0.94 (0.61, 1.45)	0.75 (0.46, 1.23)	0.31
HPFS
No.cases (n=254)	39	66	58	35	18	38
MVRR	1 (ref)	1.02 (0.67, 1.53)	1.12 (0.73, 1.72)	1.10 (0.67, 1.79)	0.90 (0.50, 1.63)	1.68 (1.02, 2.78)	0.06
Pooled
No.cases(n=655)	116	164	147	98	61	69
MVRR	1 (ref)	0.94 (0.74, 1.21)	0.97 (0.75, 1.27)	0.93 (0.69, 1.26)	0.93 (0.65, 1.31)	1.12 (0.51, 2.48) **	0.79

^*Multivariable relative risks were adjusted for age (in month), race (Caucasian vs. non-Caucasian), adult BMI (< 25, 25 –< 27.5, 27.5 –< 30, or ≥ 30 kg/m²), smoking (0, 1–10, or > 10 pack-years), history of colorectal cancer in a parent or sibling (yes or no), history of sigmoidoscopy/colonoscopy (yes or no), physical activity (< 3, 3–< 27, ≥ 27 MET-hrs/wk), regular aspirin use (yes, no), alcohol consumption (0 –< 5, 5 –< 15, or ≥ 15 g/d), 25-hydroxyvitamin D (25(OH)D) scores (tertiles), current energy-adjusted total intake of, folate, red meat, processed meat (all in tertiles), and postmenopausal hormone use (premenopausal, never, past, or current user; women only).

^**P-values for heterogeneity by sex were 0.08 for colorectal cancer, 0.67 for colon cancer, 0.64 for proximal colon cancer, 0.19 for distal colon cancer, and 0.03 for rectal cancer.