Early-onset colorectal cancer: A separate subset of colorectal cancer

Table 2 Main features of molecular classification

Category	CRC	Characteristics
		Molecular	Histopathologic	Clinical
MSI/CIMP-high	10%	MLH1 methylation	Poor differentation	Predominant location of tumor in right colon
		BRAF mutations	Lymphocytic reaction	Elderly females
			Mucinous/signet ring cells	Sporadic MSI
MSI/CIMP-low/0	5%	MMR	Lymphocytic reaction	LS
		Negative for BRAF mutations	Mucinous features
			No signet ring cells
			Good or moderate differentation
MSS/CIMP-high	5%-10%	BRAF mutations and methylation of multiple other genes	Poor differentation	Predominant location of tumor in right colon
			Signet ring cell	Elderly females
MSS/CIMP-low/0	75%-80%	CIN	Well differentiated	Predominant location of tumor in distal colon
		KRAS mutations	Heterogeneous	Male sex

CIMP: CpG island methylator phenotype; CIN: Chromosomal instability; CRC: Colorectal cancer; LS: Lynch syndrome; MMR: Mismatch repair; MSI: Microsatellite instability; MSS: Microsatellite stability