Subjects

A total of 78 tissue samples (39 colorectal tumor and 39 normal tissues) from 39 patients were collected between January 2013 and September 2014 following tumor reduction surgery in Shenzhen Second People's Hospital (Shenzhen, China). The collection of tissues was approved by the Ethics Committee of Shenzhen Second People's Hospital. Written informed consent was provided by all patients. All experiments using human blood samples were conducted in accordance with the Clinical Sample Collection and Treatment Guidelines outlined by the Ethics Committee of Shenzen Second People's Hospital. Among the 39 patients, 19 were female and 20 were male. The age of the subjects ranged from 29–84, with a mean age of 61.4 years. There were 19 cases with tumor diameters ≤5 cm and 20 cases with tumor diameters >5 cm. In the 39 patients, 29 exhibited tumors in the colon, whereas 10 patients exhibited tumors in the rectum. There were 6 cases with highly-differentiated tumors, 25 with medium-differentiated tumors and 8 with low-differentiated tumors, according to a differentiation scale determined by the Pathology Department of Shenzhen Second People's Hospital. There were 17 cases presenting lymph node metastasis, 8 cases were identified with distant metastasis and 14 cases exhibited no tumor metastasis. Pathological staging demonstrated that 19 cases were at phase I–II and 20 cases were at phase III–IV. Pathological staging was assessed according to the TNM colorectal cancer staging system of the American Joint Committee on Cancer (AJCC; AJCC staging system 7th edition 2011; cancerstaging.org) and the Union for International Cancer Control (uicc.org) standards. All patients included in the study were tested to exclude other diseases, such as gastroenteritis.