Diagnostics

All patients with suspected CRC should undergo a complete colonoscopy with biopsy of suspicious lesions. Once the diagnosis is confirmed, additional tests to stage the cancer are required to guide management.

1. Digital rectal examination

2. Felxible sigmoidoscopi with or withour anoscopy

3. Complete colonoscopy

4. Double-contrast barium enema (uncommonly performed)

• Indication: all patients with lower gastrointestinal bleeding (LGIB) or other red flags for CRC

• Findings

  • Distal rectal cancers may be palpable.

  • Evidence of blood on DRE may indicate colorectal carcinoma (CRC).

• Indication: Consider in patients with scanty intermittent hematochezia and all of the following features.

  • Age < 40 years

  • No other red flags for CRC

  • No risk factor for CRC

• Important consideration: Patients who do not fulfill any of these criteria require a complete colonoscopy.

Complete colonoscopy

• Indication: all patients with suspected CRC

• Typical findings

  • Ulceroproliferative friable mass

  • A biopsy is required to confirm the diagnosis

• Important considerations: Consider the following to identify synchronous tumors if colonoscopy cannot be completed (e.g., patients with occlusive CRC).

  • Pretreatment CT colonography or capsule endoscopy

  • Intra- or postoperative colonoscopy

  • In patients with rectal cancer, reattempt complete colonoscopy after neoadjuvant chemotherapy if there is evidence of tumor regression.

—> A complete colonoscopy is imperative in all patients with suspected/confirmed CRC as multiple adenocarcinomas (synchronous tumors) are present in up to 5% of cases

• Indication: an alternative to CT colonography in patients who decline/cannot undergo a complete colonoscopy at presentation

• Findings

  • Endoluminal filling defect typically with irregular margins

  • Apple core lesion (napkin ring sign): sharply defined circumferential narrowing of the bowel caused by a stenosing CRC

Assess for local and distant spread (T stage, N stage, and M stage).

• CT abdomen, pelvis, and chest (with IV and oral contrast)

• Typical findings of distant metastasis

  • Hepatic metastases: multiple hypodense lesions; may show peripheral washout

  • Pulmonary metastases: multiple, peripheral nodules of varying sizes

• Carcinoembryonic antigen (CEA): Obtain baseline levels in all patients before initiating treatment.

  • Monitor CEA levels during treatment and follow-up to assess response to treatment and evaluate recurrence.

  • Should not be used for screening (only prognostic marker!)

• CBC: may show microcytic anemia (iron deficiency anemia)

• Liver chemistries and coagulation: may be abnormal in patients with multiple hepatic metastases

• Counseling and genetic testing: for patients < 50 years of age with CRC or those with a family history of CRC at a young age