Are You Experiencing Colon Cancer Symptoms - Or Something Else?

If you're experiencing stomach pain, digestive problems, or painful poops, you might be wondering if it could be a sign of colon cancer. Perhaps you have a family history of colon cancer and wonder what symptoms to look out for. Here, you're provided with a more in-depth guide to colon cancer symptoms.

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Are colon cancer symptoms different for each stage?

In the first stage, you'll likely not experience any obvious signs of colon cancer. As your symptoms begin developing, they might vary depending on the location and size of the tumor in your large intestine.

Early symptoms might affect just your colon, resulting in bowel habit changes. As cancer starts growing, it might spread and produce systemic symptoms like weight loss and fatigue.

Certain changes in bowel habits that might be considered colon cancer symptoms include:

  • Constipation

  • Change in bowel movement frequency

  • Rectal bleeding

  • Change in stool consistency (watery or loose stools)

  • Abdominal pain, cramps, or bloating

  • Blood in stools (either dark tar-like stools or bright red spots)

  • A persistent feeling that you can't totally empty your bowels

What are the symptoms of each type of colon cancer?

Colorectal cancer can develop in your colon or your rectum. If it begins developing in the colon, it's called colon cancer. If it starts developing in the rectum, it's called rectal cancer.

Regardless of where it begins developing, both have a lot in common, which is why, together, they're referred to as colorectal cancer.

Symptoms of rectal cancer

The signs of rectal cancer might be similar to other types of bowel diseases like Crohn's disease or ulcerative colitis. However, while inflammatory bowel disease (IBD) symptoms subside during remission periods, symptoms of rectal cancer become more persistent and severe as your cancer develops.

Rectal tumors might change the shape, frequency, or consistency of bowel movements. Symptoms might become more severe or might increase as your cancer enlarges. Rectal cancer symptoms related to bowel habits might include:

  • Constipation

  • Diarrhea

  • Bloody stools

  • An inability to empty the bowels completely

  • Change in the shape or size of your stools

Symptoms of metastatic colorectal cancer

Individuals with metastatic colorectal cancer might not notice any symptoms before they receive a diagnosis.

Symptoms of metastatic colorectal cancer might depend on the size of your tumor(s) and where your cancer has spread outside your rectum or colon. For example:

  • Constipation, fractures, high blood calcium levels, and/or pain if your bones are affected

  • Difficulty breathing, shortness of breath, pain, fatigue, and/or coughing if your lungs are affected

  • Fatigue, increased abdominal girth, nausea, and/or jaundice if your liver is affected.

  • Confusion, headache, double or blurred vision, memory loss, seizures, and/or difficulty speaking if your spinal cord and/or brain are affected.

  • Bloating and/or loss of appetite if the lymph nodes of your abdomen are affected.

Do changes in stool or bowel habits indicate colon cancer?

How your stool looks can indicate certain things going on throughout your body. Hard, small stool indicates constipation which may simply be caused by lack of fiber in your diet or insufficient fluid intake.

If you notice any other changes, consult with your doctor to make sure it's not a colon cancer stool. For instance:

  • Color changes: If your stool is "tarry," darkened, or has blood in it, it could indicate changes inside your stomach/upper gut or colon. This is something you should have your doctor evaluate.

  • Shape changes: If your stool becomes narrow, thin, or ribbon-like, it could also indicate changes in your colon. You'll want your doctor to evaluate it to see if it could be colon cancer.

While it's common for individuals to have some changes in their bowel habits now and then, there are certain changes you'll want your doctor to evaluate if they persist.

If you notice any of the following bowel habit changes, take note of when they began and if any lifestyle changes occurred at the same time. Information like this will help your doctor determine the cause.


This is where you have less than three bowel movements in one week. It's a common gastrointestinal complaint.

However, just because you have constipation doesn't necessarily mean you have colon cancer. Other things can cause constipation, such as:

  • Poor nutritional habits/low fiber diet

  • Changes in your diet

  • Lack of physical activity

  • Dehydration

  • Stress

If you experience constipation for more than a couple of weeks, ask your doctor to examine you to determine the cause.


Diarrhea and loose stool are common occurrences. Diarrhea can be due to intolerance to things like:

  • Medication

  • Certain foods

  • Exposure to bacteria

  • Stress

Most individuals will experience at least mild cases of diarrhea a few times each year. Usually, the condition resolves itself within a few days. Your doctor will examine your diarrhea if it lasts more than a few days.

Could your symptoms be a sign of another related condition?

You might not experience symptoms right away with colorectal cancer. In fact, many symptoms similar to those of colon cancer are caused by other conditions like hemorrhoids, infection, inflammatory bowel disease, or irritable bowel syndrome.

It's important you see your doctor if you experience any of the following issues. In many instances, individuals experiencing these symptoms don't have cancer. Do consult with your doctor regardless, so they can determine the cause and treat you.

These issues might include:

  • Changes in bowel habits like constipation, diarrhea, or narrowing of your stool that lasts longer than a few days

  • Abdominal pain or cramping

  • A feeling that you have to evacuate your bowels, but doing so doesn't relieve that feeling

  • Weight loss without trying

  • Fatigue and weakness

  • Bloody stool, which might make it appear black or dark brown

  • Bleeding of the rectum with bright red blood

When to see a doctor

Colon cancer often doesn't produce symptoms until it has spread or grown. This is why it's a good idea to undergo colon cancer screening before you experience any symptoms.

Colon cancer detected early through screening before you experience symptoms is usually easier to treat. Having colorectal cancer screening can also help prevent certain colon cancers by detecting and removing polyps (pre-cancerous growths).

Your doctor will probably refer you to a gastroenterologist. They'll diagnose your colon cancer and classify its stage. They'll likely also provide you with follow-up tests during your treatment.

It's typically recommended that those with an average risk of colorectal cancer begin screening around 45 years old¹. But, if you have an increased risk as it runs in your family, you'll want to consider screening sooner.

How colon cancer is diagnosed

If you're experiencing symptoms that could be due to colon cancer or if you had a screening test that showed an abnormality, your doctor will likely order additional tests to find the cause.

They'll ask you about your medical history to see if you have any potential risk factors. They'll ask you about your symptoms (when they began and how long you've been experiencing them), and they'll ask about your family history.

Different tests your doctor might want you to get include:

  • Colonoscopy: With this test, the doctor will insert a thin tube with an attached light at the end through your anus, into your rectum and colon to take a close look inside. If they find a growth (polyp) or an abnormal lump, they'll take a piece of it (biopsy) and have it checked for cancer cells in the lab.

  • Biopsy: With a biopsy, your doctor will remove a small piece of tissue from where there might be cancer. They'll have the tissue checked for cancer cells.

  • CAT or CT scan: This is similar to an x-ray but with more detailed images of your insides. Doctors can also use CT scans to help perform biopsies and see if your cancer has spread.

  • Protein and gene tests: The doctor might have the cancer cells from the biopsy tissue tested for proteins or genes like BRAF, KRAS, and repair proteins. Knowing which proteins or genes your cancer has could help your doctor determine if treatments like immunotherapy or targeted therapy might help.

Your doctor might also order other tests like MRI scans and blood tests to see how big your cancer is and if it has spread. If you have colon cancer (or rectal cancer), your treatment will depend on the type of cancer you have, whether it has spread and how big it is. 

Many people may not want to undergo a colonoscopy to check if symptoms are related to colon cancer. Fortunately, there are alternatives available today. Learn about them here.

Have you considered clinical trials for Colon cancer?

We make it easy for you to participate in a clinical trial for Colon cancer, and get access to the latest treatments not yet widely available - and be a part of finding a cure.

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