JCOG1915: Less intensive post-operative surveillance in low risk colorectal cancer patients

Interventions: For 3 years after surgery, physical examination, tumor marker test every 6 months, and annual chest and abdominal CT scan. After 3 years after the surgery, physical examination, tumor marker test, and chest and abdominal CT scan every year. Primary outcome(s): Overall survival (OS) Study Design: single arm study, open(masking not used), uncontrolled control, single assignment, screening