Adherence to the Paleolithic diet and Paleolithic-like lifestyle reduce the risk of colorectal cancer in the United States: a prospective cohort study

Table 4 HR and 95% CIs of Incident Colorectal Cancer in the PLCO Cohort, by Quartiles of Paleolithic-Like Lifestyle score

Model	Paleolithic-Like Lifestyle score, HR (95% CI)				P for trend^a
Model	Quartile 1 (lowest)	Quartile 2	Quartile 3	Quartile 4 (highest)	P for trend^a
Colorectal cancer^b
Cases	209	165	178	142	NA
Person-years	156836	154630	195776	179486	NA
Incidence rate (95% CI)^c	1.33 (1.16, 1.53)	1.07 (0.92, 1.24)	0.91 (0.79, 1.05)	0.79 (0.67, 0.93)	NA
Unadjusted	1.00 (reference)	0.80 (0.65, 0.98)	0.68 (0.56, 0.83)	0.59 (0.48, 0.73)	< 0.001
Model 1^d	1.00 (reference)	0.82 (0.66, 1.00)	0.71 (0.58, 0.87)	0.64 (0.51, 0.80)	< 0.001
Model 2^e	1.00 (reference)	0.82 (0.67, 1.00)	0.71 (0.58, 0.87)	0.64 (0.51, 0.81)	< 0.001
Proximal colon cancer
Cases	121	105	110	84	NA
Incidence rate (95% CI)^c	0.77 (0.65, 0.92)	0.68 (0.56, 0.82)	0.56 (0.47, 0.68)	0.47 (0.38, 0.58)	NA
Unadjusted	1.00 (reference)	0.88 (0.68, 1.14)	0.73 (0.56, 0.94)	0.61 (0.46, 0.80)	< 0.001
Model 1^d	1.00 (reference)	0.88 (0.67, 1.14)	0.73 (0.56, 0.94)	0.61 (0.46, 0.82)	< 0.001
Model 2^e	1.00 (reference)	0.88 (0.67, 1.14)	0.73 (0.56, 0.94)	0.62 (0.46, 0.83)	0.001
Distal CRC
Cases	87	60	68	57	NA
Incidence rate (95% CI)^c	0.55 (0.45, 0.68)	0.39 (0.30, 0.50)	0.35 (0.27, 0.44)	0.32 (0.25, 0.41)	NA
Unadjusted	1.00 (reference)	0.70 (0.50, 0.97)	0.63 (0.46, 0.86)	0.57 (0.41, 0.80)	0.001
Model 1^d	1.00 (reference)	0.74 (0.53, 1.02)	0.69 (0.50, 0.95)	0.68 (0.48, 0.97)	0.03
Model 2^e	1.00 (reference)	0.74 (0.53, 1.03)	0.69 (0.50, 0.96)	0.69 (0.48, 0.98)	0.03

a: Trend test was performed using median value of each diet score quintile as a continuous variable
b: Including 420 proximal colon cancer cases, 272 distal CRC (that is, distal colon and rectal cancer) cases, and 2 CRC cases with an unknown site
c: Incidence rate was calculated per 1000 person-years
d: Model 1 was controlled with age (continuous), sex (male, female), race (white, no-white), education levels (high-school graduate or less, some college or college graduate)
e: Model 2 was additionally controlled with family history of colorectal cancer (no, yes or possibly), history of colon comorbidity (no, yes), history of diverticulitis or diverticulosis (no, yes), history of colorectal polyp (no, yes), history of diabetes (no, yes), history of aspirin use (no, yes), and total energy intake (continuous)
HR hazard ratio, CI confidence interval, NA not applicable

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