Alerts and Notices
SynopsisColorectal cancer is a malignancy, often adenocarcinoma, arising between the cecum and rectum. Presentation can be variable. Some tumors are detected on routine screening colonoscopy in asymptomatic patients. In other cases, patients present with bowel obstructions due to tumor growth. Patients often have an iron-deficiency anemia, which may or may not be symptomatic. They may also report thin-caliber stool or hematochezia, depending on the tumor's location, size, and degree of mucosal invasion.
Colorectal cancer is the second leading cause of cancer death in the United States. Advanced age, male sex, smoking, a family history of colorectal cancer, and inflammatory bowel disease (especially ulcerative colitis) are the strongest risk factors for developing colorectal cancer. Overall, the incidence of colorectal cancer in patients older than 50 years is declining, likely due to a combination of screening and changes in risk factors (eg, decreased smoking). But for patients younger than 50 years, the incidence of colorectal cancer has been rising. In younger patients, hereditary factors such as polyposis coli, MUTYH-associated polyposis, and hereditary nonpolyposis colon cancer (HNPCC) also increase the risk of colon cancer development. In many instances, this risk can be modified by screening or surveillance colonoscopy, as most colorectal cancers arise from adenomatous polyps, which can be fully resected. Lynch syndrome is associated with 3% of all new cases of colorectal cancer.
The most common sites of metastasis of colorectal adenocarcinoma are the liver and lungs; rarely, metastatic oral lesions occur. Cutaneous metastases of colon adenocarcinoma most commonly occur on the abdominal skin and may occur in the area of abdominal surgical scars.
Prognosis is related to cancer staging (tumor depth, lymph node involvement, metastatic spread) at time of diagnosis. Treatment often includes a combination of surgical resection and chemotherapy.
Approximately 10% of metastatic colorectal cancer patients have the BRAF V600E mutation, which is associated with a poor prognosis.
Related topic: rectal carcinoma
C18.9 – Malignant neoplasm of colon, unspecified
363406005 – Malignant tumor of colon
Differential Diagnosis & Pitfalls
- Inflammatory bowel disease (Crohn disease or ulcerative colitis)
- Internal or external hemorrhoids
- Arteriovenous malformation
- Small bowel malabsorption (eg, celiac disease, protein losing enteropathy)
- Carcinoid colonic tumors
- Colonic lymphoma
- Kaposi sarcoma in patients with human immunodeficiency virus
- Infectious colitis (eg, Clostridioides difficile colitis, amebic colitis)
- Malignancy with colorectal metastasis
- Extrinsic bowel compression (eg, genitourinary masses, cysts)