Some inherited diseases also increase the risk of developing colon cancer. One of the most common is called Lynch syndrome.
What you eat may play a role in getting colon cancer. Colon cancer may be linked to a high-fat, low-fiber diet and to a high intake of red meat. Some studies have found that the risk does not drop if you switch to a high-fiber diet, so this link is not yet clear.
Many cases of colon cancer have no symptoms. If there are symptoms, the following may indicate colon cancer:
Through screening tests, colon cancer can be detected before symptoms develop. This is when the cancer is most curable.
Your doctor will perform a physical exam and press on your belly area. The physical exam rarely shows any problems, although the doctor may feel a lump (mass) in the abdomen. A rectal exam may reveal a mass in people with rectal cancer, but not colon cancer.
Certain tests used to screen for colon cancer may suggest colon cancer. A sigmoidoscopy, or more likely, a colonoscopy, will be done to evaluate any normal results.
Only a full colonoscopy can see the entire colon. This is the best screening test for colon cancer.
Blood tests may be done for those diagnosed with colorectal cancer, including:
Complete blood count (CBC) to check for anemia
Liver function tests
If you are diagnosed with colorectal cancer, more tests will be done to see if the cancer has spread. This is called staging. CT or MRI scans of the abdomen, pelvic area, or chest may be used to stage the cancer. Sometimes, PET scans are also used.
Stages of colon cancer are:
Stage 0: Very early cancer on the innermost layer of the intestine
Stage I: Cancer is in the inner layers of the colon
Stage II: Cancer has spread through the muscle wall of the colon
Stage III: Cancer has spread to the lymph nodes
Stage IV: Cancer has spread to other organs outside the colon
Blood tests to detect tumor markers, such as carcinoembryonic antigen (CEA) may help the doctor follow you during and after treatment.
Treatment depends on many things, including the stage of the cancer. Treatments may include:
Stage 0 colon cancer may be treated by removing the tumor using colonoscopy. For stages I, II, and III cancer, more extensive surgery is needed to remove the part of the colon that is cancerous. This surgery is called colon resection (colectomy).
Most people with stage III colon cancer receive chemotherapy after surgery for 3 to 6 months. This is called adjuvant chemotherapy. Even though the tumor was removed, chemotherapy is given to treat any cancer cells that may remain.
Chemotherapy is also used to improve symptoms and prolong survival in people with stage IV colon cancer.
You may receive just one type of medicine or a combination of medicines.
Radiation therapy is sometimes used for colon cancer.
For people with stage IV disease that has spread to the liver, treatment directed at the liver can be used. This may include:
Burning the cancer (ablation)
Delivering chemotherapy or radiation directly into the liver
Freezing the cancer (cryotherapy)
Targeted treatment zeroes in on specific targets (molecules) in cancer cells. These targets play a role in how cancer cells grow and survive. Using these targets, the drug disables the cancer cells so they cannot spread. Targeted therapy may be given as pills or may be injected into a vein.
You may have targeted therapy along with surgery, chemotherapy, or radiation treatment.
You can ease the stress of illness by joining a colon cancer support group. Sharing with others who have common experiences and problems can help you not feel alone.
In many cases, colon cancer is treatable when caught early.
How well you do depends on the stage of the cancer and other factors. When treated at an early stage, many people survive at least 5 years after diagnosis. This is called the 5-year survival rate.
If the colon cancer does not come back (recur) within 5 years, it is considered cured. Stages I, II, and III cancers are possibly curable. In most cases, stage IV cancer is not thought to be curable, but there are exceptions.
Cancer spreading to other organs or tissues (metastasis)
Development of a second primary colorectal cancer
When to Contact a Medical Professional
Call your health care provider if you have:
Black, tar-like stools
Blood during a bowel movement
Change in bowel habits
Unexplained weight loss
Colon cancer can almost always be caught by colonoscopy in early stages, when it is most curable. All adults age 45 and older should have a colon cancer screening. How often you should have screening depends upon the test being used.
Colon cancer screening can often find polyps before they become cancerous. Removing these polyps may prevent colon cancer.
People with certain risk factors for colon cancer may need earlier testing (before age 45) or more frequent testing.
A healthy lifestyle also may help reduce your risk for colon cancer:
Get regular physical activity.
Don't smoke or use tobacco.
Maintain a healthy weight.
Eat a diet rich in fruits and vegetables and low in red and processed meats.
Qaseem A, Crandall CJ, Mustafa RA, et al. Screening for colorectal cancer in asymptomatic average-risk adults: a guidance statement from the American College of Physicians. Ann Intern Med. 2019;171(9) :643-654. PMID: 31683290 pubmed.ncbi.nlm.nih.gov/31683290/.
Rex DK, Boland CR, Dominitz JA, et al. Colorectal cancer screening: recommendations for physicians and patients from the U.S. Multi-Society Task Force on Colorectal Cancer. Am J Gastroenterol. 2017;112(7):1016-1030. PMID: 28555630 pubmed.ncbi.nlm.nih.gov/28555630/.
Last reviewed January 25, 2022 by Todd Gersten, MD, Hematology/Oncology, Florida Cancer Specialists & Research Institute, Wellington, FL. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team..
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