S1.

Data quality control

Source	Class	Year	Raw			Data quality control
			Sample	Item		Sample	Item
							Common	Specific
PUCH, Peking University Cancer Hospital; PUSH, Peking University Shougang Hospital; CRC, colorectal cancer.
PUCH	CRC	2010−2015	7,068	363		4,211	25 + gender + age	11
	Controls	2007−2014	80,194	220		77,099
PUSH	CRC	2011−2016	453	331		436		3
	Controls	2009−2016	66,570	434		56,799