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Colorectal Cancer Signs & Symptoms

Colorectal cancer is serious, and it's important to be aware of the signs and symptoms. Colorectal cancer refers to any cancer that begins in the colon or the rectum. Whether referring specifically to colon cancer or rectal cancer, the majority of cases begin with non-cancerous (benign) polyps that can’t be seen or felt. That’s why it’s important to take note of other physical signs and stay up-to-date on your colorectal cancer screening. Screening is the best way to detect colon cancer and rectal cancer at an early stage, making it easier to treat. Many doctors recommend colorectal cancer screening beginning at age 45, and sometimes earlier for those with high-risk factors.

Read about how colorectal cancer is affecting young adults and if there is cause for concern.

Even with regular screening, however, symptoms of colorectal cancer can appear. These can also be signs of other conditions so be sure to talk to your doctor if you notice any of the following:

Potential Colorectal Signs and Symptoms

Having these symptoms does not mean that you have cancer, but it is a good idea to schedule an appointment with your doctor if these symptoms persist.

Changes in Bowel Movements

Being constipated, having diarrhea or going more frequently are all potential symptoms. Another symptom is a condition called tenesmus, which is the feeling that one must empty their bowels, although there is nothing there.

Changes to Stool

Changes in the consistency of stool can be a sign of colorectal cancer, as are other changes. A very narrow or ribbon-like stool is one symptom. Another symptom is a darkening of the color, which may be due to the presence of blood in the stool. Visible blood in the stool or rectal bleeding are also symptoms of potential colorectal cancer. Whether you see bright red blood or dark maroon blood in your stool, it's important to take it seriously. It could be hemorrhoids or it could be a sign of something worse, especially if combined with additional symptoms, such as abdominal pain.

Lasting Abdominal Discomfort

Cramping, gas, bloating and abdominal pain that won't go away could be a symptom of colorectal cancer. Of course there are numerous other reasons for these symptoms, but when the condition persists without an obvious cause, it could be time to consult a doctor. The cancer can also cause pelvic pain. Additionally, it is possible for it to cause nausea and vomiting.


Sometimes with colorectal cancer, bleeding can happen in the digestive tract and then into stool without realizing it. Over time, this loss of blood can lead to anemia.

Weakness and Fatigue

Colorectal cancer can cause a person to feel easily tired or generally weak. If anemic, the deficit of iron in the red blood cells can also lead to the feeling of fatigue.

Unexplained Weight Loss or Loss of Appetite

While maintaining a healthy weight is one of the best ways that you can reduce your risk factors for colorectal cancer, a sudden or unexplained weight loss or loss of appetite could actually be a symptom of the illness.

What to Do If You Have Symptoms of Colorectal Cancer

Each symptom, on its own, could have many causes, but if the problems don't go away, it is important to consult a doctor to discuss colorectal signs and symptoms. Depending on the combination of symptoms as well as your risk factors for colorectal cancer your doctor can help you choose the next course of action. This is likely to include a rectal exam, as well as blood tests and possibly a colonoscopy.