Table 4.

Results of multivariate Cox regression analyses of cancer-specific survival in patients aged ≥80 years.

Variables	Cancer-specific survival
	HR (95% CI)	SE	P
T stage			<0.0001
T1	Ref
T2	1.222 (1.116–1.338)	0.046	<0.0001
T3	2.275 (2.107–2.457)	0.039	<0.0001
T4	4.089 (3.765–4.442)	0.042	<0.0001
N stage			<0.0001
N0	Ref
N1	1.968 (1.891–2.049)	0.020	<0.0001
N2	2.993 (2.861–3.132)	0.023	<0.0001
M stage
M0	Ref
M1	3.576 (3.429–3.729)	0.021	<0.0001
Race			<0.0001
White	Ref
Black	1.212 (1.143–1.286)	0.030	<0.0001
Other	1.018 (0.957–1.083)	0.032	0.565
Gender
Male	Ref
Female	1.040 (1.007–1.074)	0.017	0.019
Year of diagnosis			<0.0001
2004–2007	Ref
2008–2011	0.933 (0.900–0.967)	0.018	<0.0001
2012–2015	0.886 (0.850–0.925)	0.022	<0.0001
Tumor site
Colon cancer	Ref
Rectal cancer	1.287 (1.232–1.344)	0.022	<0.0001
Grade			<0.0001
High/moderate	Ref
Poor/anaplastic	1.157 (1.116–1.200)	0.018	<0.0001
Unknown	1.172 (1.065–1.290)	0.049	0.001
Histotype
Adenocarcinoma	Ref
Mucinous/signet ring cell	0.954 (0.907–1.004)	0.026	0.072
Chemotherapy
No	Ref
Yes	0.615 (0.589–0.643)	0.022	<0.0001