Signs and Symptoms of Colorectal Cancer

American Cancer Society   (ACS)

February 18, 2020

By: Stacy Simon 

Many of the symptoms of colorectal cancer can also be caused by something that isn’t cancer, such as infection, hemorrhoids, irritable bowel syndrome, or inflammatory bowel disease.

In many cases, people who have these symptoms do not have cancer. Still, if you have any of these problems, it is a sign that you should go to the doctor so the cause can be found and treated, if needed:

• A change in bowel habits, such as diarrhea, constipation, or narrowing of the stool, that lasts for more than a few days
• A feeling that you need to have a bowel movement that is not relieved by doing so
• Rectal bleeding
• Dark stools, or blood in the stool
• Cramping or abdominal (belly) pain
• Weakness and fatigue
• Unintended weight loss

When colorectal cancer does turn out to be the cause, symptoms often appear only after the cancer has grown or spread. That’s why it’s best to be tested for colorectal cancer before ever having any symptoms. Colorectal cancer that’s found early through screening – testing that’s done on people with no symptoms – might be easier to treat. Screening can even prevent some colorectal cancers from forming by finding and removing pre-cancerous growths called polyps.

Screening could help save your life

Colorectal cancer often doesn’t cause symptoms until it is advanced, and recent data shows the number of new cases of colorectal cancer is increasing in younger populations. This is why the American Cancer Society recommends regular colorectal cancer screening for people at average risk starting at age 45. People with a family history of the disease or who have certain other risk factors should talk with their doctor about beginning screening at a younger age. Several different tests can be used to screen for colorectal cancer. Talk with your doctor to find out which tests might be right for you, and talk to your insurance company about coverage. No matter which test you choose, the important thing is to be screened.

When colorectal cancer is found early, before it has spread anywhere, the 5-year relative survival rate is 90%. This means 9 out of 10 people with early-stage cancer survive at least 5 years. But if the cancer has had a chance to spread outside the colon or rectum, survival rates are lower.

How do they know if it’s cancer?

If your doctor finds something suspicious during a physical exam or screening test, or if you have any of the symptoms associated with colorectal cancer, you'll need to discuss any recommended follow-up exams and tests to find the cause.

Your doctor will need to know your complete medical history to check for symptoms and risk factors. It's important to know your family history. About 1 in 3 people who develop colorectal cancer have other family members – especially parents, brothers and sisters, or children – who’ve had it. (Still, most colorectal cancers occur in people without a family history of it.)

Having other colon problems can also increase risk for colorectal cancer. This includes pre-cancerous polyps, ulcerative colitis, Crohn’s disease, and hereditary syndromes such as familial adenomatous polyposis (FAP) or hereditary non-polyposis colon cancer (HNPCC), also known as Lynch syndrome. Having type 2 diabetes and certain habits such as poor diet and inactivity can also increase risk.

As part of a physical exam, your doctor will carefully feel your abdomen and also examine the rest of your body if needed. You might also get certain blood tests to help determine if you might have colorectal cancer.

Your doctor may also recommend more tests, such as colonoscopy or an x-ray or CT scan of your colon and rectum. If colorectal cancer is strongly suspected, a colonoscopy will be needed so any abnormal areas can be biopsied. In a biopsy, the doctor removes small pieces of tissue with a special instrument passed through the scope. The biopsy samples are then looked at under a microscope for cancer cells.

If you are diagnosed with colorectal cancer, treatment depends on what type of cancer it is and how early it is found. Treatment may include surgery, radiation, chemotherapy, targeted therapies, and immunotherapy. It’s important for you to be able to talk frankly and openly with your doctor, and to ask questions if you don’t understand something. Here is a list of questions to ask your doctor that you can take with you.