Table 1. Inclusion and exclusion criteria.

Inclusion criteria

(I) No age limit

(II) Preoperative colonoscopy confirmed colorectal cancer

(III) Hospitalized and operated in the participating centers

(IV) Radical operation

(V) Palliative surgery

(VI) Other limited operation for colorectal cancer

Exclusion criteria

(I) Patients undergoing emergency surgery

(II) Patients diagnosed with benign diseases

(III) Patients who had DVT or PE of both lower limbs before operation

(IV) Patients who have been enrolled in other studies or cannot obtain informed consent

(V) Patients who are already on anticoagulation drugs

DVT, deep vein thrombosis; PE, pulmonary embolism.