Facts About Colon Cancer

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Understanding Colon Cancer |  Symptoms  |  Diagnosing and Staging  |  Risk Factors  |  Resources

Symptoms

Most people don’t have signs or symptoms of colon or rectal cancer early on. That’s why it’s important to have regular colorectal cancer screenings, which can detect cancer at early stages when the cure rate is high.

Cancer that starts in different areas of the colon or in the rectum may cause different signs and symptoms. If you notice any of the following signs or symptoms, let your doctor know:

• Weight loss for no known reason
• An ongoing bloated feeling, cramping or pain in your abdomen
• Constant tiredness and weakness
• A change in bowel habits that lasts for more than a few days, such as diarrhea, constipation, narrow stools or feeling that your bowel does not empty completely
• A feeling that you need to have a bowel movement that doesn’t go away, even after going to the bathroom
• Bright red or very dark blood in your stool or bleeding from your rectum
• Low level of red blood cells (anemia) for no known reason

Usually these signs or symptoms are caused by other conditions, like infections, hemorrhoids or inflammatory bowel disease, not cancer. Your physician can help you figure out just what is causing your symptoms.

Diagnosing

If you’re having an evaluation for colorectal cancer at Fred Hutch, most likely you’ve already been diagnosed with colorectal cancer. Your referring physician based your initial diagnosis on screenings, examinations and tests that may have included the following:

• Medical history, family history and physical exam — Your physician asks questions about symptoms and risk factors, including family history, and examines you. This may include a digital rectal examination, in which the doctor inserts a lubricated, gloved finger into your rectum to feel for abnormal areas or masses. 
• Fecal occult blood test — This simple, at-home test checks for blood in your stool. Studies show that doing this test every one to two years in people ages 50 to 80 reduces deaths from colorectal cancer by as much as 30 percent.
• Fecal immunochemical test (FIT) — This is another simple, at-home test to check for blood in the stool. A version known as FIT-DNA (such as Cologuard) also checks cells from your colorectal lining for biomarkers that may indicate cancer or a precancerous condition. 
• Flexible sigmoidoscopy — Your physician looks at your rectum and lower colon using a thin, lighted tube called a sigmoidoscope. This exam can find precancerous and cancerous polyps and tumors. Regular screening with sigmoidoscopy after age 50 can reduce the number of deaths from colorectal cancer.
• Colonoscopy — Using a thin, lighted tube similar to the sigmoidoscope but longer, your doctor examines the inside of your entire colon for polyps, tumors and abnormal tissue. This is an important step if other methods suggest you may have cancer.
• Biopsy — A pathologist, a doctor who specializes in evaluating tissue samples, uses a microscope to look at polyps or tumor samples removed from your colon or rectum during your sigmoidoscopy or colonoscopy. The pathologist can see whether the cells are cancer. 

To fully understand your cancer and recommend a treatment plan, your Fred Hutch team will review your referring physician’s findings and may order one or more additional tests, such as:

• A repeat colonoscopy — if your previous procedure was incomplete
• Imaging studies — such as a computed tomography (CT) scan, positron emission tomography (PET) scan, magnetic resonance imaging (MRI) scan, endoscopic ultrasound or bone scan
• Blood tests — such as to check your levels of blood cells or your liver function

Stages

The treatment that your physician will recommend for colorectal cancer will be based in part on the stage of your cancer. The stage depends on:

• How far the cancer has spread through the wall of your colon or rectum
• Whether the cancer has spread to lymph nodes around your colon or rectum
• Whether the cancer has spread to other parts of your body, such as your liver or lungs

Colon cancers are grouped into stages I through IV, with stage I being the least advanced and stage IV being the most advanced.

What causes colon cancer?

The exact cause of colorectal cancer is not known. However, studies show that certain factors are linked to increased risk.

Fred Hutch’s Gastrointestinal Cancer Prevention Program offers a personalized approach to risk assessment, screening and prevention for people at high risk for colon cancer and other gastrointestinal cancers.