Do I Have Colorectal Cancer? Signs, Symptoms and Work-Up

Written By:Medical Content Team

What are the signs and symptoms of colorectal cancer? 

Colorectal cancer might not cause symptoms right away. In fact, many of the symptoms of colorectal cancer can also be caused by other problems, such as infection, hemorrhoids, irritable bowel syndrome, or inflammatory bowel disease.

It's important to get checked if you have any of following problems. In many cases, people who have these symptoms do not have cancer. But you should talk to your doctor if you have any of them so the cause can be found and treated.

  • 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 having one
  • Rectal bleeding with bright red blood
  • Blood in the stool, which might make it look dark brown or black
  • Cramping or abdominal (belly) pain
  • Weakness and fatigue
  • Losing weight without trying

Often colorectal cancer doesn’t cause symptoms until it 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, before you have symptoms, might be easier to treat. Screening can even prevent some colorectal cancers by finding and removing pre-cancerous growths called polyps.

How does the doctor know if it’s cancer?

If you have symptoms that might be caused by colorectal cancer or if a screening test shows something not normal, your doctor will want to do more testing to find the cause. 

Your doctor will ask about your medical history to learn about possible risk factors, including check for symptoms and. It's important to know your family history. You will also be asked if you’re having any symptoms and, if so, when they started and how long you’ve had them. 

You might be able to have a virtual visit to talk with your doctor about symptoms or risk factors that might be worrying you. But, depending on your symptoms, your doctor might want you to schedule an in-person visit so you can be examined. As part of a physical exam, your doctor will carefully feel your abdomen for masses or enlarged organs, and also examine the rest of your body. You may also have a 
digital rectal exam (DRE). During this test, the doctor inserts a lubricated, gloved finger into your rectum to feel for any abnormal areas. 

Your doctor may also want you to get more tests such as:

  • Colonoscopy:  A colonoscopy is a test where a thin tube with a light on the end is put through the anus, into the rectum and colon to look closely at the inside. If any abnormal lump (mass) or growth
    (polyp) is found, a piece of it can be taken (a biopsy) and checked in the lab for cancer cells.
  • Biopsy: During a biopsy, the doctor takes out a small piece of tissue where the cancer might be. The tissue is checked for cancer cells. This is the best way to know if you have cancer.    
  • CT or CAT scan: A CT scan is like an x-ray, but the pictures of your insides are more detailed. CT scans can also be used to help do a biopsy and can show if the cancer has spread.
  • Ultrasound: For this test, a small wand is moved around on your skin. It gives off sound waves and picks up the echoes as they bounce off tissues. The echoes are made into a picture on a computer screen. It’s used to help find cancer and see if it has spread.
  • Gene and protein tests: The cancer cells in the biopsy tissue might be tested for genes or proteins such as KRAS, BRAF, MMR and MSI. Knowing which genes or proteins your cancer has can help the doctor decide if treatments like targeted therapy or immunotherapy might help.

Other tests, such as MRI scans, x-rays and blood tests may also be done to look at how big the cancer is and whether it has spread.

What happens if I have colorectal cancer?

If you have colon or rectal cancer, treatment depends on which type of cancer it is, how big it is, and whether it has spread. Treatment may include surgery, radiation, chemotherapy, targeted therapy or immunotherapy. Many people get more than one type of treatment. It’s important to talk openly with your doctor and ask questions if you don’t understand something. Here is a list of questions to ask your doctor that you can take with you.

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