Table 4.

Multivariable associations of dietary factors with risk of colorectal cancer according to refined subsites in the NHS, NHS2, and HPFS.

Risk factor	Proximal colon cancer				Distal colon cancer			Rectum cancer			P for overall heterogeneity c	P for linear heterogeneity d
	Cecum	Ascending colon	Transverse colon	Overall	Descending colon	Sigmoid colon	Overall	Rectosigmoid	Rectum	Overall
	n=474	n=633	n=250	n=1357	n=221	n=750	n=971	n=202	n=528	n=730
Total fiber intake, per 30g/day
HR	0.93	1.09	0.60	0.92	1.36	0.86	0.95	1.55	0.59	0.77
95% CI	0.46–1.86	0.60–2.01	0.23–1.58	0.61–1.39	0.49–3.72	0.49–1.48	0.58–1.54	0.55–4.42	0.31–1.14	0.45–1.34	0.30	0.45
Ptrend	0.83	0.77	0.30	0.70	0.55	0.58	0.83	0.41	0.12	0.36
P for heterogeneity within main subsites c				0.18			0.76			0.12
Whole grain intake, per 20 g/day
HR	1.08	0.95	0.87	0.98	1.00	0.91	0.93	1.07	0.75	0.82
95% CI	0.91–1.27	0.82–1.11	0.69–1.10	0.88–1.08	0.78–1.28	0.79–1.04	0.82–1.04	0.82–1.38	0.63–0.88	0.71–0.94	0.03	0.02
Ptrend	0.39	0.54	0.23	0.65	0.99	0.16	0.20	0.63	<0.001	0.005
P for heterogeneity within main subsites c				0.17			0.80			0.03
Cereal fiber intake, per 5 g/day
HR	1.13	0.96	0.84	0.99	0.95	0.92	0.93	1.11	0.60	0.71
95% CI	0.87–1.46	0.76–1.20	0.58–1.21	0.85–1.16	0.64–1.40	0.75–1.13	0.77–1.11	0.75–1.65	0.46–0.77	0.57–0.88	0.003	0.007
Ptrend	0.36	0.70	0.34	0.92	0.79	0.45	0.42	0.59	<0.001	0.001
P for heterogeneity within main subsites c				0.18			0.83			0.01
Vitamin D intake, per 400IU/day
HR	0.87	0.81	0.70	0.80	0.81	0.76	0.77	0.89	0.84	0.87	0.71	0.97
95% CI	0.71–1.06	0.67–0.96	0.53–0.93	0.71–0.91	0.60–1.09	0.64–0.89	0.66–0.88	0.66–1.21	0.69–1.02	0.74–1.03
Ptrend	0.16	0.02	0.02	<0.001	0.16	<0.001	<0.001	0.47	0.07	0.10
P for heterogeneity within main subsites c				0.30			0.84			0.78
Marine omega-3 fatty acid intake, per 0.2 g/day
HR	0.90	0.97	1.02	0.95	1.09	1.08	1.08	0.81	0.99	0.94
95% CI	0.76–1.05	0.84–1.12	0.82–1.27	0.86–1.05	0.86–1.38	0.95–1.23	0.97–1.21	0.63–1.04	0.85–1.15	0.82–1.07	0.37	0.49
Ptrend	0.18	0.67	0.85	0.30	0.47	0.22	0.16	0.09	0.86	0.33
P for heterogeneity within main subsites c				0.59			0.94			0.19
Total red meat intake, per 3 serving/week
HR	1.02	1.04	1.14	1.05	1.05	1.04	1.04	0.97	1.07	1.05
95% CI	0.93–1.12	0.96–1.13	1.00–1.29	1.00–1.11	0.92–1.20	0.96–1.11	0.97–1.11	0.84–1.12	0.98–1.17	0.97–1.13
Ptrend	0.70	0.36	0.046	0.07	0.47	0.34	0.24	0.65	0.11	0.22
P for heterogeneity within main subsites c				0.19			0.72			0.15	0.46	0.82
Processed red meat intake, per 3 serving/week
HR	0.96	0.97	1.20	1.01	1.23	1.17	1.19	1.01	1.21	1.16
95% CI	0.78–1.17	0.81–1.16	0.92–1.57	0.90–1.14	0.92–1.64	1.00–1.37	1.03–1.36	0.73–1.37	1.00–1.46	0.99–1.36	0.12	0.04
Ptrend	0.68	0.72	0.18	0.85	0.16	0.04	0.01	0.98	0.04	0.07
P for heterogeneity within main subsites c				0.18			0.64			0.23
Unprocessed red meat intake, per 3 serving/week
HR	1.06	1.07	1.16	1.08	0.95	0.95	0.95	1.01	1.14	1.11
95% CI	0.92–1.22	0.94–1.21	0.96–1.41	1.00–1.18	0.77–1.18	0.85–1.06	0.86–1.05	0.81–1.26	1.00–1.30	0.99–1.24	0.31	0.96
Ptrend	0.46	0.32	0.13	0.06	0.66	0.35	0.30	0.91	0.05	0.08
P for heterogeneity within main subsites c				0.19			0.87			0.27
Total folate intake, per 400μg/day
HR	0.94	0.89	0.68	0.86	1.10	0.76	0.83	0.73	0.85	0.82
95% CI	0.76–1.16	0.73–1.07	0.50–0.92	0.76–0.98	0.81–1.49	0.64–0.91	0.71–0.96	0.52–1.01	0.69–1.04	0.69–0.98	0.17	0.30
Ptrend	0.57	0.20	0.01	0.02	0.56	0.002	0.01	0.06	0.12	0.03
P for heterogeneity within main subsites c				0.12			0.05			0.41
Calcium intake, per 300mg/day
HR	0.96	0.95	0.88	0.94	0.87	0.83	0.84	0.90	0.92	0.91
95% CI	0.87–1.05	0.88–1.02	0.78–1.01	0.89–0.99	0.76–1.00	0.77–0.90	0.79–0.90	0.79–1.04	0.84–1.00	0.85–0.98	0.06	0.19
Ptrend	0.33	0.18	0.06	0.02	0.047	<0.001	<0.001	0.15	0.06	0.02
P for heterogeneity within main subsites c				0.27			0.68			0.73
Empirical dietary inflammatory pattern (EDIP) score, per 1 unit
HR	1.54	1.16	1.01	1.27	1.24	1.52	1.45	1.21	1.13	1.19
95% CI	1.06–2.23	0.84–1.61	0.61–1.69	1.02–1.58	0.72–2.12	1.13–2.05	1.12–1.88	0.69–2.15	0.79–1.60	0.89–1.61	0.50	0.71
Ptrend	0.02	0.36	0.96	0.03	0.44	0.006	0.005	0.51	0.51	0.24
P for heterogeneity within main subsites c				0.24			0.38			0.87
Empirical dietary index for hyperinsulinemia (EDIH), per 1 unit
HR	1.21	1.03	2.19	1.27	2.02	1.64	1.72	0.71	1.54	1.29
95% CI	0.75–1.95	0.67–1.58	1.16–4.12	0.96–1.69	1.01–4.03	1.13–2.39	1.24–2.39	0.34–1.48	0.98–2.40	0.88–1.88	0.08	0.45
Ptrend	0.44	0.90	0.02	0.10	0.047	0.009	0.001	0.36	0.06	0.19
P for heterogeneity within main subsites c				0.11			0.60			0.05

^aAge- and cohort-stratified Cox proportional hazards model was used with adjustment for age (continuous), race, height (continuous), family history of colorectal cancer (yes or no), history of lower gastrointestinal endoscopic screening (yes or no), body mass index (continuous), pack-years of smoking (continuous), physical activity (continuous), alcohol intake (continuous), and regular aspirin use (yes or no).

^bFor dietary factors, test for trend was conducted using the median of each quintile as a continuous variable.

^cHeterogeneity was tested by using meta-regression method with a subsite-specific random effect term as a nominal variable.

^dLinear heterogeneity was tested by using meta-regression method with a subsite-specific random effect term as an ordinal variable.