Colorectal Cancer

For average-risk patients, screening for colorectal cancer (CRC) should begin at age 45 years and continue until age 75 years. For adults aged 76 to 85, the decision whether to screen for CRC should be individualized, taking into consideration the patient's overall health and prior screening history (see also the U.S. Preventive Services Task Force's 2021 recommendation statement for screening for colorectal cancer and the American College of Gastroenterology’s [ACG] clinical guidelines for colorectal cancer screening).

There are multiple options for CRC screening, including

The ACG colorectal cancer screening guidelines recommend colonoscopy every 10 years or annual FIT as the preferred screening tests. Alternative CRC screening tests are available for patients who decline colonoscopy or for whom economic issues preclude screening with colonoscopy and for whom the need for repeated testing with FIT is problematic. Patients with a family history of a 1st-degree relative with colorectal cancer diagnosed prior to age 60 should undergo colonoscopy every 5 years, beginning at age 40 years, or 10 years before the age the relative was diagnosed, whichever comes first. Screening of patients with high-risk conditions (eg, ulcerative colitis Diagnosis Ulcerative colitis is a chronic inflammatory and ulcerative disease arising in the colonic mucosa, characterized most often by bloody diarrhea. Extraintestinal symptoms, particularly arthritis... read more ) is discussed under the specific condition.

Fecal immunochemical tests for blood are more sensitive and specific for human blood than older guaiac-based stool tests, which can be affected by many dietary substances. However, a positive test for blood can result from nonmalignant disorders (eg, ulcers, diverticulosis), and a negative test does not rule out cancer because cancers do not bleed continuously.

Fecal DNA testing detects DNA mutations and methylation markers shed from a colonic tumor. The test typically is combined with FIT, and the combined test is approved for screening average-risk patients. Patients with a positive fecal DNA-FIT test should get a follow-up colonoscopy within 6 months to reduce the risk of missing advanced colon cancer. Nearly 10% of patients with a positive fecal DNA-FIT test result have a normal colonoscopy; such patients can have a repeat fecal DNA-FIT test in 1 year or a repeat colonoscopy in 3 years. If these tests are negative, they can return to the average-risk colon cancer screening schedule.

CT colonography CT colonography X-ray and other imaging contrast studies visualize the entire gastrointestinal tract from pharynx to rectum and are most useful for detecting mass lesions and structural abnormalities (eg, tumors... read more (virtual colonoscopy) generates 3D and 2D images of the colon using multidetector row CT and a combination of oral contrast and gas distention of the colon. Viewing the high-resolution 3D images somewhat simulates the appearance of optical endoscopy, hence the name. It has some promise as a screening test for people who are unable or unwilling to undergo endoscopic colonoscopy but is less sensitive and highly interpreter-dependent. It avoids the need for sedation but still requires thorough bowel preparation, and the gas distention may be uncomfortable. Additionally, unlike with optical colonoscopy, lesions cannot be biopsied during the diagnostic procedure.

Video capsule endoscopy of the colon has many technical problems and is not currently acceptable as a screening test.

Blood-based tests (eg, Septin 9 assay) have been approved for screening average-risk patients but are not widely used because of inadequate sensitivity.

Patients with positive fecal occult blood tests require colonoscopy, as do those with lesions seen during sigmoidoscopy or an imaging study. All lesions should be completely removed for histologic examination. If a lesion is sessile or not removable at colonoscopy, surgical excision should be strongly considered.

Barium enema x-ray, particularly a double-contrast study, can detect many lesions but is somewhat less accurate than colonoscopy and is not currently acceptable as follow-up to a positive fecal occult blood test.

Once cancer is diagnosed, patients should have abdominal CT, chest x-ray, and routine laboratory tests to seek metastatic disease and anemia and to evaluate overall condition.

Elevated serum carcinoembryonic antigen (CEA) levels are present in 70% of patients with CRC, but this test is neither sensitive nor specific and therefore is not recommended for screening. However, if the CEA level is high preoperatively and low after removal of a colon tumor, monitoring the level may help detect recurrence earlier. CA 19­-9 and CA 125 are other tumor markers that may be similarly used.

Colon cancers that were removed during surgery are now routinely tested for the gene mutations that cause Lynch syndrome Lynch Syndrome Lynch syndrome is an autosomal dominant disorder responsible for 2 to 3% of cases of colorectal cancer. Symptoms, initial diagnosis, and treatment are similar to other forms of colorectal cancer... read more . People with relatives who developed colon, ovarian, or endometrial cancer at a young age or who have multiple relatives with those cancers should be tested for Lynch syndrome.

Surgery for cure can be attempted in the 70% of patients presenting without metastatic disease. Attempt to cure consists of wide resection of the tumor and its regional lymphatic drainage with reanastomosis of bowel segments.

For rectal cancer, sphincter-saving surgical resection can be done in patients with rectal cancer that has a distal margin of ≥ 1.0 cm, instead of the usual 5-cm length, without significant risk of local recurrence or decreased long-term survival. Sphincter-saving procedures have been done in patients with rectal cancer that has a distal margin of < 1cm, but these patients have an increased risk of local recurrence and decreased long-term survival. The problem with sphincter-saving procedures is often more functional (eg, fecal leakage, incontinence) in nature rather than oncologic (eg, local recurrence, decreased survival). If there is local recurrence or poorly tolerated bowel function after a sphincter-saving procedure, then an abdominoperineal resection (APR) with permanent colostomy (1 Treatment references Colorectal cancer is extremely common. Symptoms include blood in the stool and change in bowel habits. Screening using one of several methods is recommended for appropriate populations. Diagnosis... read more ) is done.

With liver metastases, resection of a limited number (1 to 3) of liver metastases is recommended in select nondebilitated patients as a subsequent procedure. Criteria include patients whose primary tumor has been resected, whose liver metastases are in one hepatic lobe, and who have no extrahepatic metastases. Only a small number of patients with liver metastases meet these criteria, but in such cases 5-year postoperative survival is 25%.

Chemotherapy improves survival by at least 10 to 30% in colon cancer patients with positive lymph nodes. Rectal cancer patients with 1 to 4 positive lymph nodes benefit from combined radiation and chemotherapy; when > 4 positive lymph nodes are found, combined modalities are less effective. Preoperative radiation therapy and chemotherapy to improve the resectability rate of rectal cancer or decrease the incidence of lymph node metastasis are standard.

After curative surgical resection of colorectal cancer, surveillance colonoscopy should be done 1 year after surgery or after the clearing preoperative colonoscopy (2 Treatment references Colorectal cancer is extremely common. Symptoms include blood in the stool and change in bowel habits. Screening using one of several methods is recommended for appropriate populations. Diagnosis... read more ). A second surveillance colonoscopy should be done 3 years after the 1-year surveillance colonoscopy if no polyps or tumors are found. Thereafter, surveillance colonoscopy should be done every 5 years. If the preoperative colonoscopy was incomplete because of an obstructing cancer, a completion colonoscopy should be done 3 to 6 months after surgery to detect any synchronous cancers and to detect and resect any precancerous polyps (2 Treatment references Colorectal cancer is extremely common. Symptoms include blood in the stool and change in bowel habits. Screening using one of several methods is recommended for appropriate populations. Diagnosis... read more ).

Additional screening for recurrence should include history, physical examination, and serum carcinoembryonic antigen levels every 3 months for 3 years and then every 6 months for 2 years. Imaging studies (CT or MRI) are often recommended at 1-year intervals but are of uncertain benefit for routine follow-up in the absence of abnormalities on examination or blood tests.

When curative surgery is not possible or the patient is an unacceptable surgical risk, limited palliative surgery (eg, to relieve obstruction or resect a perforated area) may be indicated; median survival is 7 months. Some obstructing tumors can be debulked by electrocoagulation or held open by stents. Chemotherapy may shrink tumors and prolong life for several months.

Newer drugs used singly or in drug combinations include capecitabine (a 5-fluorouracil precursor), irinotecan, and oxaliplatin. Monoclonal antibodies such as bevacizumab, cetuximab, and panitumumab are also being used with some effectiveness. No regimen is clearly more effective for prolonging life in patients with metastatic colorectal cancer, although some have been shown to delay disease progression. Chemotherapy for advanced colon cancer should be managed by an experienced chemotherapist who has access to investigational drugs.

When metastases are confined to the liver but cannot be surgically resected, hepatic artery infusion with floxuridine or radioactive microspheres, given either intermittently in a radiology department or given continuously via an implantable subcutaneous pump or an external pump worn on the belt, may offer more benefit than systemic chemotherapy; however, these therapies are of uncertain benefit. When metastases are also extrahepatic, intrahepatic arterial chemotherapy offers no advantage over systemic chemotherapy. For selected patients with ≤ 3 liver lesions, stereotactic radiation therapy or thermal ablation using radiofrequency or microwave treatments can be considered.