What are the symptoms of colorectal cancer?

Jill Onesti, MD
Surgical Oncology
Colorectal cancer can cause symptoms of obstruction, as the tumor grows to a point where it blocks your colon or your rectum. You may notice this as pain in that area of your belly, difficulty in passing stool, or sudden onset of nausea and vomiting. If there is a partial blockage of the colon, your stools may appear narrower or thin in caliber -- even as thin as a pencil. Another common symptom is seeing blood in your stools. It is important not to assume any blood in your stools is from a hemorrhoid, but rather discuss this with your doctor and undergo further evaluation.
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Christine M. Bouchard, MD
Colorectal Surgery
Colorectal cancer is often a silent disease, meaning it develops with no symptoms at all until it is very advanced. When symptoms do occur, they may include the following:
  • Blood in or on the stool
  • Change in bowel habits
  • Narrower stools
  • Bloating/fullness
  • Vomiting
  • Diarrhea, constipation or feeling of incomplete evacuation
  • Unintentional weight loss
  • Rectal bleeding
  • Constant tiredness or new fatigue
Cary L. Gentry, MD
Colorectal Surgery
The most common symptoms are rectal bleeding, changes in bowel habits such as constipation and diarrhea and change in size of the stool. Some people do not have symptoms, so it is important to begin colorectal screening (colonoscopy) beginning at age 50. For those individuals with a family history of colon cancer, they should begin screenings at 40. 
Jon A. Horine, MD
Internal Medicine
Often there are no symptoms of colorectal cancer, which is why screening is started at a certain age. Symptoms can include bleeding, anemia, abdominal pain and unexplained weight loss. Through screening it's possible to lower the cancer rates and, most importantly, lower the colorectal death rate.
In its early stage, colorectal cancer usually produces no symptoms. Polyps may be small and produce few, if any, symptoms. Some important warning signs include:
  • Any notable change in bowel movement consistency or frequency
  • Dark or light blood in the stool or rectal bleeding
  • Abdominal discomfort or bloating
  • Unexplained fatigue, loss of appetite and/or weight loss
Cedrek McFadden, MD
Colorectal Surgery

The symptoms of colorectal cancer can include abdominal pain, rectal bleeding, a change in bowel habits, or even an unintentional weight loss. However, some patients experience no symptoms at all. That is why screenings are generally recommended beginning at age 50.

Penn Medicine

The colon is the largest part of the large intestine, also known as the large bowel. The colon's function is to change liquid waste into solid waste and prepare it to be expelled from the body.

Symptoms of colon cancer include:

  • Bleeding from the rectum
  • Blood (bright red or very dark) in the stool or toilet after a bowel movement
  • A change, or narrowing of the stool
  • Cramping or pain in the abdomen
  • Feeling the need to have a bowel movement, but not having one
  • Excessive fatigue
  • Frequent gas, bloating or feeling of fullness
  • Weight loss for no known reason
  • Nausea and vomiting

Rectal cancer is cancerous tissue that grows along and invades the wall of the rectum. Rectal cancer and colon cancer are very similar and share many common features. The difference in location creates important differences in how each is treated. Rectal cancer, like colon cancer, may start as a polyp that becomes cancerous.

Symptoms of rectal cancer include:

  • Change in bowel habits including: diarrhea, constipation, feeling that the bowel has not completely emptied, stools that are narrow in shape
  • Bright red or dark blood in the stool
  • Abdominal discomfort
  • Change in appetite
  • Losing weight without dieting
  • Fatigue
Symptoms of colorectal cancer include a recent change in bowel habits, blood in the stool, weight loss, fatigue, anemia and abdominal pain. People with colorectal cancer may have any combination of the above symptoms or have no symptoms at all. Often, early stages of colorectal cancer can be detected with screening colonoscopy before the person ever experiences any symptoms. The symptoms of colorectal cancer can be vague and could be due to another medical condition, so it is always wise to check with your primary care doctor if you are experiencing any of these symptoms.
Lawrence S. Friedman, MD
Colorectal cancer is the third most common form of cancer in both men and women, with an estimated 143,000 new cases diagnosed in the United States each year. Early on, colon cancer causes no symptoms. Later, its symptoms can be similar to those of inflammatory bowel disease (IBS) -- abdominal pain, cramping, bloating, gas pains, and a change in bowel patterns. In addition, blood in the stool or rectal bleeding is often present. Advanced cancer is likely to cause bloody bowel movements, severe constipation if the intestine is obstructed, and weight loss. Thus, it's vital to get checked without delay should these symptoms occur.

The good news is that most cases of colon cancer can be prevented through screening. Almost all precancerous growths (polyps) can be spotted and removed during a colonoscopy. Early-stage, localized colon cancers are curable by surgery in 90% of cases.
Precancerous polyps and colorectal cancer don't always cause symptoms, especially at first. You could have polyps or colorectal cancer and not know it. That is why having a screening test is so important. Symptoms for colorectal cancer may include:
  • Blood in or on the stool (bowel movement).
  • Stomach pain, aches or cramps that do not go away.
  • Losing weight and you don't know why.
These symptoms may be caused by something other than cancer. If you're having any of these symptoms, the only way to know what is causing them is to see your doctor.

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Very often, a lot of patients have trouble believing they have colorectal cancer because they do NOT have any symptoms. For others, they might have abdominal pain, bloating, change in bowel habit or weight loss. Unfortunately with symptoms, their cancer might already be advance. Another non-specific symptom might be bleeding. Since there we don't know if someone is constipated or have a colon cancer, it is advisable to see your doctor for any changes or concerns and to schedule a colonoscopy by age 50.

Aurora Health Care
Colorectal cancer (cancer of the colon or rectum, both of which make up the large bowel) is most curable when found before it causes symptoms. When symptoms do occur, they might include:
  • Changes in bowel habits
  • Rectal bleeding or blood in the stool (bright red or very dark)
  • Abdominal (stomach) cramps or frequent gas pains or bloating
  • Unexplained weight loss or fatigue
Good In Bed
Internal Medicine
Colon cancer shows up in the tissues of the colon, while rectal cancer shows up in the tissues of the rectum. Worried you might have it? Symptoms to look out for include bloody stools; cramping, bloating, and gas pains; abdominal pain; diarrhea or constipation; chronic fatigue; and other symptoms of anemia (due to intestinal bleeding).
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The symptoms of colorectal cancer are bleeding, constipation, and general changes in the bowel movement. Yet, in most cases, there are no symptoms for colorectal cancer, which is why for the average risk individual should have a regular colonoscopy starting at the age of 50.
Steven V. Gurland, MD
Internal Medicine
The first sign of colon cancer is traces of blood found in the stool. As the cancer grows symptoms of changing bowel habits occur usually constipation. abdominal pain is associated with signs of obstruction. If not treated early it will spread and then numerous systemic symptoms can occur.

A common symptom of colorectal cancer is a change in bowel habits. Symptoms include:

• Having diarrhea or constipation
• Feeling that your bowel does not empty completely
• Finding blood (either bright red or very dark) in your stool
• Finding your stools are narrower than usual
• Frequently having gas pains or cramps, or feeling full or bloated Losing  weight with no known reason
• Feeling very tired all the time
• Having nausea or vomiting

Most often, these symptoms are not due to cancer. Other health problems can cause the same symptoms. Anyone with these symptoms should see a doctor to be diagnosed and treated as early as possible.

Usually, early cancer does not cause pain. It is important not to wait to feel pain before seeing a doctor.

This answer is based on source information from National Cancer Institute.

Some individuals with colorectal cancer (colon cancer) have no symptoms, while other do. Symptoms of colorectal cancer may resemble other conditions, so always consult your physician if you experience any of the following:

- A change in bowel habits, such as constipation, diarrhea, frequency of bowel movements, or narrowing of the stool that continues for more than a few days
- Rectal bleeding or traces of blood in the stool
- Stomach pain, cramping, or stomach discomfort
- Fatigue and weakness
- Decreased appetite and weight loss
- Jaundice (yellow-colored skin or eyes)
- Enlarged abdomen
- Feeling of discomfort in the pelvic area

Continue Learning about Colon Cancer

Colon Cancer

Caused by growths that turn malignant, colon cancer develops slowly over several years.The cancer begins when precancerous growths called adenomatous polyps form in the tissues of the colon, which makes up the lower part of our di...

gestive system. Polyps can be detected through colon screenings. A colonoscopy uses a thin, lighted tube to search for polyps, cancer and abnormal areas in the colon and rectum. A colonoscopy is recommended at least every 10 years, starting at the age of 45 for African-Americans who are at greater risk for the cancer and at 50 for other races. Your risk for colon cancer increases if you have had previous cancers, a family history of colon or rectal cancers, or have ulcerative colitis. See your doctor if you have rectal bleeding, notice changes in your bowel movements or have unexplained weight loss. To prevent colon cancer, get screened as recommended by your doctor, maintain a healthy diet, exercise often and quit smoking if you currently do.

Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.