Table 2. Gene mutation index and genomic complexity in young and elderly CRC patients.

	Onset <50 years, n = 24	Onset >70 years, n = 17	P-values
Mean number of mutations per patient	1.04	1.47	0.14
Median number of regions with copy number aberration per patient	43.29	26.88	0.02
Median percentage of normal copy number per patient	71.72	77.23	0.66

Median number of mutations per patient ( = gene mutation index) is based on data from analyses of KRAS, BRAF, PIK3CA, PTEN and TP53. Median number of regions with copy number aberrations ( = genomic complexity) and median percentage of normal copy number per patient are based on results from aCGH analysis.