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

Table 3 Bivariate and multivariable analysis for progression-free survival

Characteristic	Crude HR (95% CI)	P-value* (bivariate^a)	Adjusted HR (95% CI)	P-value* (multivariable^a)
Primary tumor location
Right vs. Left	2.09 (1.31–3.33)	0.002	1.55 (0.92–2.61)	0.099
Age
>60 years vs. ≤ 60	0.77 (0.54–1.08)	0.133	0.77 (0.53–1.13)	0.180
Gender
Female vs. Male	1.15 (0.80–1.64)	0.449	1.11 (0.75–1.64)	0.616
Stage at presentation
Stage IV vs. Stage I-III	0.99 (0.66–1.49)	0.965
Histologic grade
P/D or SRC vs. W/D or M/D	5.37(2.24–12.87)	<0.001	3.06 (1.22–7.67)	0.017
Presence of liver metastasis
Yes vs. No	1.04 (0.73–1.50)	0.816
Presence of lung metastasis
Yes vs. No	0.87 (0.63–1.21)	0.419
Presence of peritoneal metastasis
Yes vs. No	2.53 (1.53–4.19)	<0.001	2.08 (1.19–3.63)	0.010
Number of metastasized organs
≥ 2 vs. 1	1.11 (0.80–1.53)	0.543
BRAF
Mutant vs. Wild-type	3.56 (2.11–6.01)	<0.001	3.07 (1.73–5.46)	<0.001
PIK3CA
Mutant vs. Wild-type	2.60 (0.95–7.11)	0.062

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