Perform a physical examination and obtain a careful personal and family history. Evaluate entire large bowel by colonoscopy.
Obtain baseline laboratory tests: complete blood cell count, international normalized ratio (INR), activated partial thromboplastin time, liver and renal function tests, and serum carcinoembryonic antigen (CEA). Serum CEA serves as a marker for monitoring CRC response to treatment, but it is too insensitive and nonspecific to be used as a screening test for early-stage CRC.
Radiographic imaging studies may include chest radiographs, bone scan, chest and abdominal computed tomography scans, positron emission tomography, ultrasonography, and magnetic resonance imaging.
Determine CRC stage at diagnosis to predict prognosis and develop treatment options. Stage is based on size of the primary tumor (T1–4), presence and extent of lymph node involvement (N0–2), and presence or absence of distant metastases (M).
✓ Stage I disease involves tumor invasion of the submucosa (T1) or muscularis propria (T2) and negative lymph nodes.
✓ Stage II disease involves tumor invasion through the muscularis propria into pericolorectal tissues (T3), or penetration to ...