Table 3.

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

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
Smoking
Packyears of smoking, per 20 pack-year
HR	1.12	1.14	1.12	1.13	1.10	1.03	1.05	1.11	1.12	1.11
95% CI	1.03–1.22	1.06–1.22	1.00–1.26	1.07–1.19	0.97–1.25	0.96–1.11	0.98–1.12	0.96–1.27	1.03–1.21	1.04–1.20	0.61	0.40
Ptrend	0.01	0.0005	0.05	<0.001	0.13	0.43	0.15	0.15	0.009	0.003
P for heterogeneity within main subsites c				0.80			0.25			0.77
Packyears of smoking before age 30, per 20 pack-year
HR	1.08	1.27	1.43	1.21	1.37	1.19	1.23	1.27	1.26	1.17
95% CI	0.81–1.46	0.98–1.65	0.99–2.07	1.01–1.43	1.06–2.33	0.95–1.49	1.00–1.50	0.81–1.97	0.96–1.64	0.93–1.48	0.67	0.62
Ptrend	0.60	0.07	0.06	0.03	0.03	0.13	0.048	0.30	0.10	0.18
P for heterogeneity within main subsites c				0.10			0.21			0.76
Alcohol intake, per 14 g/day
HR	0.99	1.02	1.25	1.06	1.18	1.11	1.12	1.10	1.14	1.12
95% CI	0.89–1.11	0.92–1.13	1.11–1.41	0.99–1.13	1.02–1.37	1.02–1.20	1.05–1.20	0.93–1.30	1.04–1.26	1.03–1.22	0.11	0.09
Ptrend	0.91	0.71	<0.001	0.10	0.02	0.01	0.001	0.27	0.008	0.01
P for heterogeneity within main subsites c				0.02			0.32			0.66
BMI, per 5 kg/m2
Men	n=197	n=143	n=107	n=447	n=70	n=292	n=362	n=68	n=186	n=254
HR	1.21	1.32	1.16	1.24	1.49	1.28	1.32	1.14	1.33	1.25
95% CI	0.97–1.50	1.03–1.68	0.87–1.55	1.08–1.43	1.13–1.96	1.11–1.49	1.16–1.50	0.80–1.64	1.08–1.63	1.05–1.49
Ptrend	0.09	0.03	0.31	0.003	0.005	0.001	<0.001	0.47	0.008	0.01	0.69	0.70
P for heterogeneity within main subsites c				0.87			0.21			0.62
Women	n=277	n=490	n=143	n=910	n=151	n=458	n=609	n=134	n=342	n=476
HR	1.11	1.13	1.27	1.15	1.12	1.21	1.19	1.06	1.24	1.19
95% CI	0.97–1.28	1.01–1.25	1.06–1.52	1.06–1.24	0.92–1.37	1.09–1.35	1.09–1.31	0.85–1.32	1.09–1.40	1.07–1.32	0.63	0.29
Ptrend	0.14	0.03	0.01	<0.001	0.25	0.0003	<0.001	0.59	<0.001	0.002
P for heterogeneity within main subsites c				0.68			0.33			0.22
BMI at age 18/21, per 5 kg/m2
Men	n=197	n=143	n=107	n=447	n=70	n=292	n=362	n=68	n=186	n=254
HR	1.11	1.02	1.08	1.07	0.94	1.12	1.08	1.00	1.12	1.06	0.85	0.81
95% CI	0.93–1.32	0.85–1.22	0.86–1.35	0.96–1.20	0.75–1.18	0.98–1.29	0.96–1.21	0.77–1.30	0.94–1.33	0.92–1.22
Ptrend	0.23	0.85	0.50	0.21	0.60	0.10	0.22	0.99	0.22	0.43
P for heterogeneity within main subsites c				0.84			0.20			0.43
Women	n=277	n=490	n=143	n=910	n=151	n=458	n=609	n=134	n=342	n=476
HR	1.09	1.24	1.33	1.20	1.22	1.21	1.21	1.26	1.25	1.25
95% CI	0.90–1.32	1.07–1.42	1.03–1.71	1.09–1.33	0.96–1.55	1.05–1.40	1.07–1.37	0.98–1.62	1.07–1.47	1.09–1.44	0.98	0.50
Ptrend	0.39	0.003	0.03	<0.001	0.11	0.007	0.002	0.07	0.006	0.001
P for heterogeneity within main subsites c				0.70			0.94			0.96
Waist circumference, per 10 cm
Men	n=197	n=143	n=107	n=447	n=70	n=292	n=362	n=68	n=186	n=254
HR	1.17	1.31	1.09	1.21	1.83	1.27	1.37	1.31	1.25	1.27
95% CI	0.99–1.39	1.09–1.57	0.86–1.38	1.08–1.34	1.43–2.33	1.12–1.44	1.22–1.53	1.02–1.69	1.04–1.49	1.10–1.47	0.09	0.58
Ptrend	0.06	0.004	0.47	<0.001	<0.001	<0.001	<0.001	0.04	0.02	0.001
P for heterogeneity within main subsites c				0.44			0.004			0.89
Women	n=277	n=490	n=143	n=910	n=151	n=458	n=609	n=134	n=342	n=476
HR	0.98	1.08	1.14	1.06	1.02	1.09	1.08	1.04	1.07	1.06
95% CI	0.87–1.11	0.99–1.18	0.97–1.34	0.99–1.13	0.87–1.21	0.99–1.20	0.99–1.17	0.88–1.23	0.96–1.19	0.97–1.16	0.70	0.59
Ptrend	0.72	0.08	0.10	0.08	0.79	0.07	0.08	0.62	0.24	0.22
P for heterogeneity within main subsites c				0.26			0.54			0.69
Physical activity, per 7.5 MET-hours/week b
HR	0.99	1.01	0.97	0.99	0.96	0.96	0.96	0.97	0.98	0.98
95% CI	0.94–1.04	0.97–1.06	0.90–1.04	0.96–1.02	0.89–1.03	0.93–1.00	0.93–1.00	0.90–1.05	0.93–1.03	0.94–1.02	0.49	0.35
Ptrend	0.58	0.63	0.35	0.65	0.25	0.07	0.04	0.43	0.42	0.31
P for heterogeneity within main subsites c				0.96			0.76			0.43
Height, per 10 cm
HR	1.14	1.25	1.23	1.20	1.20	1.10	1.12	1.21	1.27	1.25
95% CI	0.99–1.31	1.10–1.42	1.01–1.49	1.10–1.30	0.97–1.47	0.99–1.23	1.02–1.24	0.97–1.50	1.11–1.46	1.12–1.40	0.60	0.77
Ptrend	0.08	<0.001	0.04	<0.001	0.09	0.08	0.02	0.09	<0.001	<0.001
P for heterogeneity within main subsites c				0.56			0.48			0.66

^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 physical activity, the follow-up started in 1986 in NHS.

^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.