Table 4.

PIK3CA mutation in colorectal cancer and patient mortality

PIK3CA status	Total No.	No. of events	Colorectal cancer-specific mortality			Overall mortality
			Univariate HR (95% CI)	Stage- stratified HR (95% CI)	Multivariate stage- stratified HR (95% CI)	No. of events	Univariate HR (95% CI)	Stage- stratified HR (95% CI)	Multivariate stage- stratified HR (95% CI)
Wild-type	981	277	1 (referent)	1 (referent)	1 (referent)	467	1 (referent)	1 (referent)	1 (referent)
Mutant (exon 9 or 20 )	189	51	0.95 (0.70–1.28)	1.03 (0.77–1.40)	1.07 (0.79–1.45)	85	0.92 (0.73–1.16)	0.97 (0.76–1.22)	0.91 (0.72–1.15)
Mutation in only exon 9	109	29	0.94 (0.64–1.38)	1.05 (0.72–1.55)	1.05 (0.71–1.56)	48	0.93 (0.69–1.25)	0.99 (0.73–1.33)	0.90 (0.67–1.22)
Mutation in only exon 20	73	18	0.83 (0.52–1.34)	0.87 (0.4–1.40)	0.96 (0.59–1.55)	30	0.77 (0.53–1.12)	0.80 (0.55–1.15)	0.80 (0.55–1.16)
Mutations in both exon 9 and exon 20	7	4	2.84 (1.05–7.69)	3.61 (1.32–9.87)	3.51 (1.28–9.62)	7	3.37 (1.58–7.15)	3.91 (1.83–8.36)	2.68 (1.24–5.77)

The multivariate, stage-stratified Cox regression model initially included age, sex, year of diagnosis, tumor location, tumor grade, microsatellite instability, CpG island methylator phenotype, KRAS mutation, BRAF mutation and LINE-1 methylation. A backward elimination with a threshold of P = 0.05 was used to select variables in the final models.

CI, confidence interval; HR, hazard ratio.