Colorectal Cancer: Diagnosis and Treatment

Diagnosis

Presenting symptoms and complications are listed above.

Colonoscopic Examination

• Guiac-positive stools should prompt evaluation with a colonoscopy.
• A colonoscopy with biopsy can diagnose colon cancer and allow for removal of early lesions during the same procedure.
• A barium enema is not as sensitive as colonoscopy (for diagnosis), and also does not permit polyp removal.
• A "virtual colonoscopy" via CT or MRI is under investigation, but reliability is not yet established.

Laboratory Findings

• Complete blood count may reveal microcytic anemia from chronic blood loss.
• Tumor markers (CEA, CA 125, CA 19-9, CA 50, CA 195) are not sufficiently specific to screen for colon cancer, but can aid in determining prognosis and disease recurrence.

Metastatic Workup

• Liver function tests and CT scans of the thorax, abdomen, and pelvis.

Staging

The TNM (Tumor, Node, Metastasis) classification is the preferred system for tumor staging. The CT scan helps determine the clinical stage.

• TNM stage I: Tumor is localized to the mucosa and submucosa.
• TNM stage II: Tumor has extended into the muscle layer but without lymph node involvement.
• TNM stage III: Regional lymph node involvement.
• TNM stage IV: Distant Metastases.

Treatment

Surgical resection is the definitive treatment and is often curative for early cancers.

Surgical resection and adjuvant chemotherapy (eg, 5-fluorouracil, leucovorin, oxiliplatin) are indicated for advanced cancers.

Radiation and chemotherapy are mainstays of treatment for rectal cancers, in addition to surgical resection.

Liver metastases are treated by resection, chemoembolization, or direct-infusion chemotherapy into the hepatic artery.

Avastin, an angiogenesis inhibitor, has been approved by the FDA as a first-line treatment for metastatic colon cancer.