Selection criteria
primary CRC lesions
ADENOCARCINOMA
The SEER*Stat version 8.4.0.1 software was used to extract the demographic, clinical, and survival data of SMPCC patients registered on the SEER database between 2000 and 2017. The inclusion criteria were as follows: (1) Two or more primary CRC lesions diagnosed in the same patient; (2) Pathologically confirmed adenocarcinoma; (3) The diagnosis interval for the identification of the different primary CRC lesions of less than 6 months [Flowchart illustrating the patient selection process