What is colorectal cancer?
Colorectal cancer is a cancer that starts in the colon or rectum. These cancers can also be named colon cancer or rectal cancer depending on where they start.
Colorectal cancers are the second leading cause of cancer death in the United States.
What causes colorectal cancer?
Cancer forms when healthy cells turn abnormal. Unlike healthy cells, which grow, multiply and die at a set time, abnormal cells multiply out of control and don’t die. The abnormal cells create a mass, or a tumor, and can spread to nearby tissue or elsewhere in the body. When abnormal cells invade other parts of the body, it has metastasized.
Colon cancer doesn’t have a single cause. Nearly all colon cancers begin as noncancerous (benign) polyps, or clumps of cells, which slowly develop into cancer.
Anal cancer is related to a sexually transmitted infection called human papillomavirus (HPV). HPV is thought to be the most common cause of anal cancers given that evidence of HPV is detected in the majority of anal cancers.
Who is at risk for colorectal cancer?
Risk factors for anal cancer include:
- Age: Most anal cancer cases occur in people 50 years old and older.
- Several sexual partners: People who have many sexual partners are at greater risk of anal cancer.
- Anal sex: Engaging in anal sex increases risk of anal cancer.
- Smoking: Cigarettes might increase risk of anal cancer.
- Cancer history: People who have had other cancers near the anus — such as cervical, vulvar or vaginal cancer — have a higher risk of anal cancer.
- Human papillomavirus (HPV): HPV, a sexually transmitted infection that can also cause genital warts, increases risk of several cancers, including anal cancer.
- Immunosuppressant drugs or conditions: Those who take drugs to suppress their immune system might be at higher risk for anal cancer. HIV, which is the virus that causes AIDS, suppresses the immune system and increases anal cancer risk.
Risk factors for colon and rectal cancer include:
- Age: Most colon cancer cases occur in people 50 years old and older. However, the rates of colon cancer in younger people are increasing, but doctors don’t know why.
- Race: African-Americans are at higher risk of colon cancer than people of other races.
- Personal history of colorectal cancer or polyps: If you’ve previously had colon cancer or noncancerous colon polyps, you have an increased risk of future colon cancer.
- Inflammatory intestinal conditions: Chronic inflammatory diseases of the colon, including ulcerative colitis and Crohn’s disease, can heighten your risk of colon cancer.
- Inherited syndromes that increase colon cancer risk: Certain gene mutations passed through generations of your family can significantly increase your risk of colon cancer. However, only a small percentage of colon cancers are linked to inherited genes.
- Family history of colon cancer: If you have a blood relative who has had the disease, you’re more likely to develop colon cancer.
- Low-fiber and high-fat diet: Colon cancer and rectal cancer might be associated with a typical Western diet, which is low in fiber and high in fat and calories.
- Sedentary lifestyle: People who are inactive are at a higher risk of developing colon cancer.
- Diabetes: People with diabetes or who are insulin-resistant have an increased risk of colon cancer.
- Weight: People who are obese have a higher risk of colon cancer and dying of colon cancer than with people considered normal weight.
- Smoking: Cigarettes might increase risk of colon cancer.
- Alcohol: Heavy alcohol consumption increases risk of colon cancer.
- Radiation therapy: Radiation therapy aimed at the abdomen to treat previous cancers heightens risk of colon cancer.
What are the symptoms of colorectal cancer?
Symptoms of colorectal cancer are the same as symptoms for colon cancer* and anal cancer:
- A persistent change in your bowel habits, including diarrhea or constipation, or change in the consistency of your stool
- Rectal bleeding or blood in your stool
- Persistent abdominal discomfort, such as cramps, gas or pain
- Feeling that your bowel doesn’t empty completely
- Weakness or fatigue
- Unexplained weight loss
- Anal pain or itching
- A mass or growth in the anal canal
*Many people with colon cancer, a type of colorectal cancer, experience no symptoms in the early stages of the disease. When symptoms do appear, they can vary depending on the cancer’s size and location.
How is colorectal cancer diagnosed?
There are various tests and procedures used to diagnose anal cancer:
- Examining your anal canal and rectum for abnormalities
- Inspecting your anal canal and rectum
- Taking an ultrasound of your anal canal
- Removing a sample of tissue for laboratory testing
There are a couple tests and procedures used to help diagnose colon cancer:
- A scope to examine the inside of your colon, a procedure known as a colonoscopy
- Blood tests
- Stool studies looking for abnormal DNA
How is colorectal cancer treated?
Several treatments are available to help control colorectal cancer, including surgery, radiation therapy and drug treatments, including chemotherapy, targeted therapy and immunotherapy.
A special emphasis throughout the history of Columbia Surgical Associates has been the treatment of cancer, and the surgeons offer patients multi-disciplinary care for colorectal cancer. In-office transrectal ultrasound studies facilitate and expedite initial evaluation, and patient care is coordinated with medical and radiation oncology colleagues.
What are the possible complications of colorectal cancer?
Complications of colorectal cancer can include:
- Blockage of the colon, causing bowel obstruction
- Return of colon cancer
- Development of a second primary colorectal cancer
Anal cancer rarely metastasizes to distant parts of the body, but when it does, those tumors are difficult to treat. When it metastasizes, anal cancer most commonly spreads to the liver and lungs.
- Colon cancer: Overview. (2019). https://www.mayoclinic.org/diseases-conditions/colon-cancer/symptoms-causes/syc-20353669
- Colon cancer: Diagnosis & treatment. (2019). https://www.mayoclinic.org/diseases-conditions/colon-cancer/diagnosis-treatment/drc-20353674
- Colorectal cancer. (2020). https://medlineplus.gov/ency/article/000262.htm