Understanding Colorectal Cancer Symptoms

Colorectal cancer symptoms may be minor or non-existent during the early stages of the disease. Since colorectal cancer almost always develops from precancerous polyps or growths that originate in the colon or rectum, participating in regular screening can help to find and remove these polyps before they become cancerous. Be sure to talk to your doctor about when you should start regular colorectal cancer screening.

WHAT ARE THE EARLY WARNING SIGNS OF COLORECTAL CANCER?

If you do notice any of the following early warning signs, be sure to inform your doctor as soon as possible:

• Unexplained changes in bowel habits, such as constipation or diarrhea
• Change in size/shape of stools, such as being narrower than usual
• The urge to have a bowel movement but nothing passes
• Rectal bleeding
• Blood in or on the stool, ranging from bright red to dark black
• Persistent abdominal pain/discomfort including bloating, fullness, cramps, gas pain
• Unexplained weight loss
• Weakness and fatigue
• Anemia, caused by iron deficiency

Many of these signs may also be caused by other less serious gastrointestinal conditions, such as ulcers, Crohn’s disease or hemorrhoids, but they should always be discussed with your doctor to receive the correct diagnosis.

Even though colorectal cancer is more commonly diagnosed in people over the age of 50, rates are on the rise in younger adults. For more information on early age onset colorectal cancer, see our Never Too Young (N2Y) Program.

IF I AM EXPERIENCING SYMPTOMS OR I HAVE AN ABNORMAL SCREENING TEST, WHAT NEXT?

Your doctor will talk to you about your medical history to learn about possible risk factors, such as family cancer history. They will also ask you how long and how often you have been experiencing the symptom(s).

While you may be able to have an initial virtual appointment with your doctor, depending on the symptom(s) your doctor may request an in-person visit so that you can be physically examined. A physical exam consists of carefully feeling your abdomen for any masses or abnormalities, as well as examining the rest of your body. Your doctor may also perform a digital rectal exam which involves inserting a lubricated, gloved finger into the rectum to examine for any abnormalities.

Further diagnostic tests may be requested by your doctor, such as:

• Colonoscopy: a thin tube with a light and camera on the end is inserted into the anus, rectum, and colon to carefully examine for the presence of polyps (growths) or other abnormal masses. If anything is found, a piece is removed (a biopsy) and sent to a laboratory to be checked for cancer cells.
• Biopsy: during a biopsy, a small amount of tissue is removed from where the cancer might be and is examined for the presence of cancer cells. This is a very accurate test to determine whether you have cancer.
• CT or CAT scan: combines a series of X-ray images taken from many different angles around the body and uses a computer to create detailed images of the bones, blood vessels and soft tissues. CT scans can be used to help do a biopsy and can show if the cancer has spread to other parts of the body.
• Ultrasound scan: sometimes called a sonogram, an ultrasound scan sends special sound waves to specific parts of the inside of the body and will create an image on the computer based on the echoes that bounce off the tissues. This procedure can be used to find cancer and see if it has spread to other parts of the body.
• Biomarker testing: if cancer cells are found in the biopsy, they might be tested for the presence of specific genes or proteins referred to as biomarkers known to be involved in colorectal cancer, such as KRAS, BRAF, and MSI. By knowing what biomarkers are present in your tumour tissue, your medical team can get a better idea of what treatment options, such as targeted therapy or immunotherapy, are most appropriate for you.

Learn more about diagnosis by visiting our Diagnosing Colorectal Cancer page.

FREQUENTLY ASKED QUESTIONS RELATED TO COLORECTAL CANCER SYMPTOMS

CAN COLON CANCER CAUSE RECTAL BLEEDING?

Yes. Rectal bleeding may be either bright red or dark red blood on the toilet paper after a bowel movement or red or pink water in the toilet bowl. Having rectal bleeding does not necessarily mean that you have colon cancer or rectal cancer, but if you are experiencing it be sure to talk about it with your doctor as soon as possible to determine the cause.

CAN COLORECTAL CANCER CAUSE LOWER BACK PAIN?

Depending on the size of the tumour and its closeness to surrounding tissues and organs, it is possible that colorectal cancer can cause lower back pain. If you are experiencing persistent lower back pain or any signs or symptoms of colorectal cancer, be sure to talk to your doctor so that appropriate diagnostic tests can be performed.

HOW TO TELL IF YOU HAVE COLON CANCER OR HEMORRHOIDS?

Both colon cancer and hemorrhoids can present with symptoms of rectal bleeding or blood in or around the stool. It is important to see your doctor if you experience any kind of rectal bleeding, especially if the bleeding is accompanied with a change in bowel habits. Your doctor may perform a physical examination or further diagnostic tests to correctly identify the cause. See our Diagnosis Colorectal Cancer page for more information..

I HAVE BEEN DIAGNOSED WITH COLORECTAL CANCER, NOW WHAT?

Receiving a cancer diagnosis can be shocking, disorienting, and overwhelming. Take the time to talk openly with your medical team to learn more about your diagnosis and all of your treatment options, including those that may only be available through clinical trials.

Treatment for colorectal cancer will depend on the type (colon or rectal), the size of the tumour, and whether it has spread to other parts of the body. Treatment usually includes a combination of chemotherapy, radiation therapy, surgery, targeted therapy, or Immunotherapy.

Visit our Colorectal Cancer Treatment page for more information.

Last updated: July 2021