Table 5.

Age-Adjusted C Statistics for a Model of Colorectal Cancer Incidence, Overall and by Tumor Subsite and Age^a and With and Without the Inclusion of Screening, Nurses’ Health Study, 1980–2010

Analysis and Cancer Subgroup	No. of Casesb	Adjusted for All Covariatesc	P Valued	Adjusted for All Covariates Except Screening	P Valued
		C Statistic (Standard Error)		C Statistic (Standard Error)
Colorectale	1,759	0.607 (0.007)		0.599 (0.007)	0.0002f
Colon	1,342	0.603 (0.008)	0.03	0.599 (0.008)	0.80
Rectal	376	0.639 (0.014)		0.603 (0.014)
Proximal	821	0.603 (0.010)	0.16	0.602 (0.010)	0.65
Distal	521	0.625 (0.012)		0.609 (0.012)
Subgroup and age, years
Colorectal
<70	1,155	0.620 (0.008)	0.013	0.610 (0.008)	0.015
≥70	604	0.584 (0.012)		0.575 (0.012)
Colon
<70	851	0.617 (0.010)	0.015	0.613 (0.010)	0.015
≥70	491	0.577 (0.013)		0.573 (0.013)
Proximal
<70	471	0.621 (0.013)	0.030	0.620 (0.013)	0.034
≥70	350	0.578 (0.015)		0.578 (0.015)
Distal
<70	380	0.628 (0.014)	0.68	0.618 (0.014)	0.26
≥70	141	0.617 (0.023)		0.587 (0.024)
Rectal
<70	277	0.640 (0.016)	0.90	0.605 (0.017)	0.83
≥70	99	0.636 (0.028)		0.598 (0.028)

^aC statistics adjusted for age in 10-year age groups.

^b There was a total of 1,239,121 person-years among noncases, of which 1,000,230 corresponded to <70 years of age and 238,891 to ≥70 years of age.

^c All covariates included age, family history, red meat intake, processed meat intake, folate intake, calcium intake, smoking history, body mass index, physical activity level, height, alcohol intake, aspirin use, and PMH use.

^dP value for the difference between C statistics.

^e The total number of colorectal cancer cases does not equal the sum of the total numbers of colon and rectal cancer cases due to incomplete information on tumor site.

^fP value for the difference between C statistics with and without screening.