Colon cancer symptoms: What are the early signs of colon cancer?

Signs of colon cancer include bloody stools, persistent abdominal pain, or symptoms of bowel obstruction

Overview: What does colon cancer feel like?

Colon cancer is a cancer of the large intestine, the last part of the digestive system. Healthcare professionals generally consider it part of a single diagnosis, colorectal cancer, or cancer of the colon and rectum (the last several inches of the colon adjoining the anus). Colorectal cancer is a severe, life-threatening medical condition responsible for about 1 out of 2 cancer deaths in the U.S. 

Colon cancer is slow-growing, so often there are no symptoms in the early stages. As the tumor grows, people will start to notice problems. The first sign may be a dull ache. Bowel movements could change. Constipation or diarrhea might go on for weeks or months. Because the growing tumor could narrow the width of the colon or rectum, people may notice their stools are getting long and thin. The rectum or the colon may start bleeding. Eventually, the tumor may completely block the colon or tear a hole in the colon wall, causing intense pain, swelling, or bleeding. Colorectal cancer may eventually spread to other parts of the body, causing other symptoms.

Key takeaways:

  • Colon cancer is a common health condition that can affect anyone regardless of age, sex, race, or ethnicity. 
  • Early signs of colon cancer include abdominal pain, rectal bleeding, and changes in bowel habits.
  • Serious symptoms of colon cancer such as bloody stools, severe, persistent abdominal pain, or symptoms of bowel obstruction (cramping, abdominal swelling, inability to pass stools) may require immediate medical attention.
  • Healthcare professionals are unsure about what causes colon cancer. You may be at risk for developing colon cancer symptoms if you are older than 50, have a family history of colon cancer or polyps, have certain genetic mutations or syndromes such as Lynch syndrome or family adenomatous polyposis (FAP), or have had abdominal radiation treatment as a child. Other risk factors include inflammatory bowel disease (ulcerative colitis or Crohn’s disease), diabetes, obesity, red meat diet, smoking, and drinking alcohol. 
  • Colon cancer requires a medical diagnosis.
  • Colon cancer generally requires treatment. Colon cancer symptoms may or may not resolve with treatment in a variable time frame depending on the treatment.
  • Treatment of colon cancer may include endoscopic surgery, open surgery, and anticancer medications. Read more about colon cancer treatments here.
  • Untreated colon cancer could result in complications like bowel obstruction, perforation, bleeding, growth of the tumor, metastasis, and death.
  • Use SingleCare coupons for colon cancer medications oxaliplatin, leucovorin, and capecitabine to save up to 80%.

RELATED: What is oxaliplatin? Uses, warnings, and interactions

What are the early signs of colon cancer?

In the early stages, colon cancer often does not have symptoms. Since the only definitive way to diagnose colon cancer is by examining the colon lining with a colonoscope, early symptoms that would trigger a colonoscopy include:

  • Diarrhea, constipation, or other bowel movement abnormalities that last for weeks
  • Rectal bleeding
  • Abdominal discomfort, pain, or cramping

Other colon cancer symptoms

Digestive system symptoms of colorectal cancer can include:

  • Abdominal pain 
  • Bowel movement abnormalities (constipation, diarrhea, or long, thin stools)
  • Blood in the stools
  • Bloating
  • Rectal bleeding
  • Acid regurgitation
  • Bowel obstruction

Other symptoms of colon cancer could include:

  • Anemia
  • Loss of appetite
  • Fatigue
  • Weight loss
  • Increased urination
  • Blood in the urine
  • Genital bleeding

Colon cancer vs. irritable bowel syndrome symptoms

The symptoms of irritable bowel syndrome (IBS) are very similar to the symptoms of colon cancer. Both are characterized by abdominal pain and bowel movement problems. Unlike colon cancer, IBS, although often a chronic disorder which can be quite uncomfortable, is a relatively unthreatening medical condition. Most people with IBS are diagnosed younger than 50 years of age, but colorectal cancer is more commonly discovered in people older than 50. Colon cancer also has a few “red flag” symptoms like rectal bleeding and unexplained weight loss, neither of which are associated with IBS.

Shared symptoms
  • Abdominal pain, discomfort, or cramping
  • Bowel movement irregularities
  • Bloating
  • Gas
  • Cramping
Unique symptoms
  • Rectal bleeding
  • Involuntary weight loss
  • Loss of appetite
  • Blood in the stools

RELATED: IBS treatments and medications

Stages of colon cancer: How can I tell which one I have?

Healthcare professionals diagnose colon cancer in one of four stages. These stages help guide the most appropriate treatment.

  • Stage 0: When the tumor is only present on the outermost layer of the inner lining of the colon, it’s called a carcinoma in situ which means a “tumor in its original place.” 
  • Stage I: In the first stage, the tumor has invaded only the inner layers of the colon.
  • Stage II: In the second stage, the tumor has invaded deeper layers of the colon.
  • Stage III: In the third stage, the cancer cells have spread to nearby lymph nodes. The tumor may have grown through the colon and into nearby organs.
  • Stage IV: In the fourth stage, the cancer has spread to other organs that aren’t near the colon. This is called metastasis.

In the earliest stages, colorectal cancer usually doesn’t cause symptoms. It is usually detected by colorectal cancer screening. Since treatment at this stage has the best prognosis, this is a good argument to get regular colorectal screening starting at the age of 45.

When to see a doctor for colon cancer symptoms

The time to see a doctor for colon cancer screening is before any symptoms appear. Colon cancer develops from colon tissue growths called polyps. If they develop into a tumor, it usually takes about 10 to 15 years. These polyps can be spotted and removed before they become cancerous. Though several tests can screen for colorectal cancer, the gold standard is a colonoscopy. The doctor inspects the lining of the colon using a colonoscope, a camera attached to a long tube, to look for polyps, tumors, or other problems. 

At the minimum, people should be screened when they turn 50, but many doctors now believe it’s best to get screened at 45 years of age. People with relatives who have had colon polyps or cancer should get screened as early as 40 years of age. Screening should be repeated every 10 years unless the doctor wants it done more frequently. Cancer prevention screening is the best time to see a doctor.

If screening isn’t done, then see a doctor if any of the common symptoms of colon cancer such as abdominal pain, bowel movement irregularities, or rectal bleeding persist for more than a couple of weeks. Extreme pain, blood in the stools, or symptoms of bowel obstruction are signs that emergency medical treatment may be needed.

A colon cancer diagnosis will be made by a doctor who specializes in gastrointestinal problems. The gastroenterologist will perform a colonoscopy to examine the tissues lining the colon or a sigmoidoscopy to study the lining of the rectum and the colon above it. The scope will have tools to take tissue samples for biopsy. Another doctor will examine these tissues under a microscope. This visual inspection of the colon lining and microscopic study of the tissues is enough to make a diagnosis.

RELATED: 7 medical tests you need when you turn 50

Complications of colon cancer

Colon cancer is a slow-growing cancer, but it does grow. Untreated colon cancer can lead to complications such as:

  • Growth of the cancer
  • New tumors 
  • Bowel obstruction
  • Perforation
  • Spread of the cancer to the lymph nodes and other organs 
  • Death

How to treat colon cancer symptoms

Treatment of colon cancer will depend on the stage. At all stages, the tumor will have to be removed (resection). If found early enough, the tumor may be removed using an endoscope. Follow-up treatment with cancer drugs will probably not be necessary at the very earliest stages.

At later stages, a surgeon may need to surgically open the abdomen to remove the tumor and tissues around it. If the cancer has spread, the surgeon may need to remove part or all of the colon, a procedure called a colectomy. Radiation treatment may be required before or after surgery.

People who undergo open surgery for more advanced colon cancer will start anticancer drugs about six months later. The most common drug given is oxaliplatin along with other cancer-killing drugs. 

If the cancer has spread to the rest of the body, treatment options involve chemotherapy and specialty drugs like targeted therapy, monoclonal antibodies, and immune-suppressing drugs.

RELATED: Colon cancer treatments and medications

Living with colon cancer

Although colon cancer is a frightening diagnosis, many people survive. Once a person is in remission, life won’t exactly return to normal. There is a risk that colon cancer will come back, so there are a number of responsibilities a survivor will have:

  • Keep all follow-up appointments with members of the cancer care team 
  • Follow all instructions for follow-up screening tests, blood tests, imaging, and colonoscopic examination
  • At the minimum, follow-up colonoscopies will be performed one year and three years after surgery and every five years after that
  • CT scans will probably be required every three or six months
  • Side effects from cancer drugs can last even after they’re no longer being taken, so be familiar with these side effects and how to manage them
  • Follow any dietary instructions given by the care team
  • Adopt a healthy lifestyle that includes a healthy diet, physical activity, and weight maintenance
  • Avoid alcohol—drinking increases the risk of recurrence
  • Quit smoking—people who smoke are at an increased risk of dying from the cancer

Most importantly, get screened

Early detection of colon cancer saves lives and is a key component of cancer prevention. If you are 45 or older, ask your primary doctor about getting screened for colon cancer. Colorectal polyps, the precursors to colorectal tumors, can be detected and removed during a colonoscopy. If you just can’t face a colonoscopy, there is a stool test that can detect a colon tumor. It’s not as accurate as a colonoscopy, but at least it’s one way to spot the problem when it’s early enough to do something about it.

FAQs about colon cancer symptoms

Are colon cancer symptoms constant?

Colon cancer symptoms will change over time as the cancer grows. Abdominal pain is one of the most common symptoms. At first, it will feel like a dull ache. As the cancer grows, it will evolve into something more like cramping. The pain will get more severe. Other parts of the body might hurt as the cancer spreads to other organs and tissues.

At what stage does colon cancer become painful?

In the earlier stages of colon cancer, there may be no pain. If there is, it might feel more like an ache than pain. Abdominal pain is more typical in the advanced stages of colon cancer and tends to feel like cramping or bloating.

What does untreated colon cancer feel like?

Many of the symptoms of colon cancer first appear as the cancer enters more advanced stages. These include pain, bleeding, and bowel movement problems. These symptoms will worsen as the tumor grows. When cancer cells spread to other parts of the body, other symptoms might appear. For instance, in 80% to 90% of people with metastatic colon cancer, the cancer spreads to the liver. This will cause symptoms like jaundice, loss of appetite, fever, and itchy skin. 

What’s next? Additional resources for people with colon cancer symptoms

Test and diagnostics


Scientific studies and clinical trials

More information on related health conditions


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