Colon cancer is caused by colon cells growing out of control. As the number of cells grows, they form into a tumor. Most colon tumors begin when normal colon tissue forms an adenomatous polyp. As the polyp grows larger, a tumor is formed. Colon cancer that has spread from the colon to another part of the body is called metastatic cancer. The rectum is at the end of the colon. It is usually empty except for when you are about to have a bowel movement. Stool goes from your colon, through the rectum, and out of your body. Rectal cancer is caused by rectal cells growing out of control. As the number of cells grows, they form into a tumor.
- History of polyps and Ulcerative colitis or Crohn’s disease
- Genetic mutations like inherited colorectal cancer syndromes
- Eating high fats food, excessive red meat, and not eating enough fruits and vegetables
- Not exercising and weighing more than you should
The early stages of colorectal cancer may not have any symptoms. As a polyp grows into a tumor it can bleed or obstruct the colon, which will then cause symptoms.
- Bleeding from the rectum
- Blood in the stool or toilet after a bowel movement
- A change in the shape of the stool, such as thinning
- Cramping pain in the abdomen
- Feeling the need to have a bowel movement when you don’t actually have to
Screening for colorectal cancer consists of tests that screen for just cancer and tests that screen for both polyps and cancer. Tests that screen for polyps and cancer include:
- Flexible Sigmoidoscopy
- Double-contrast barium enema
- CT colonography (virtual colonoscopy)
Tests that screen mainly for cancer include:
- Stool testing for blood
- Stool testing for DNA
Screening should start at age 45 according to the American Cancer Society and at age 50 according to the USPSTF, or earlier if you have a family history of colorectal cancer. Ask your doctor about what screening recommendations are appropriate for you.
To guide treatment, colorectal cancer is “staged.” This stage is based on:
- Size and location of the tumor
- Whether cancer cells are in the lymph nodes
- Whether cancer cells are in other parts of the body
Stages range from stage I (smallest, most confined tumors) to stage IV (tumors that have spread to other parts of the body, also called metastatic cancer). The stage of colorectal cancer will guide your treatment plan.
In general, the following treatments are used:
- Surgery is the most commonly used treatment. During surgery either a polyp or the surrounding tissue are removed or the tumor and surrounding tissues (and lymph nodes if necessary) are removed and the two ends of the remaining colon are reconnected. If it is not possible to reconnect the colon, a colostomy is created.
- Chemotherapy may be given after surgery to prevent a recurrence.
- Targeted therapy, medications that work specifically against a certain target, can be used to treat certain types of colon cancer.
- Radiation and Interventional Radiology procedures can be used to treat areas in the body to which colon cancer spread.