Primary tumor location predicts poor clinical outcome with cetuximab in RAS wild-type metastatic colorectal cancer

Table 2 Bivariate and multivariable analysis for overall survival

Characteristic	Crude HR (95% CI)	P-value* (bivariate^a)	Adjusted HR (95% CI)	P-value* (multivariable^a)
Primary tumor location
Right vs. Left	2.29 (1.46–3.62)	<0.001	1.84 (1.10–3.09)	0.021
Age
>60 years vs. ≤ 60	1.06 (0.76–1.47)	0.750	1.07 (0.75–1.51)	0.720
Gender
Female vs. Male	0.92(0.65–1.30)	0.623	0.97 (0.66–1.40)	0.852
Stage at presentation
Stage IV vs. Stage I-III	1.12 (0.77–1.63)	0.554
Histologic grade
P/D or SRC vs. W/D or M/D	4.35 (2.21–8.57)	<0.001	3.08 (1.49–6.34)	0.002
Presence of liver metastasis
Yes vs. No	1.29 (0.91–1.82)	0.156
Presence of lung metastasis
Yes vs. No	0.84 (0.61–1.15)	0.279
Presence of peritoneal metastasis
Yes vs. No	2.91 (1.79–4.75)	<0.001	2.05 (1.17–3.60)	0.013
Number of metastasized organs
≥ 2 vs. 1	1.10 (0.80–1.52)	0.540
BRAF
Mutant vs. Wild-type	3.24 (1.94–5.43)	<0.001	2.84 (1.60–5.03)	<0.001
PIK3CA
Mutant vs. Wild-type	1.97 (0.80–4.84)	0.138

Abbreviations: HR hazard ratio, CI confidence interval, P/D poorly differentiated, SRCC signet ring cell carcinoma, W/D well-differentiated, M/D moderately differentiated
^* P-value by Cox’s proportional hazards regression
^aClinically meaningful variables and those with p < 0.05 by bivariate analysis were entered into the multivariable analysis model