Colon cancer symptoms

Knowing the symptoms of colon cancer and signs of rectal cancer, and understanding your risks of developing it, may stop this cancer from happening to you—or help you get a diagnosis as early as possible.

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Colorectal cancer symptoms: 7 signs to see your doctor

Some early stages of colorectal cancer may not show any signs. (Which is why screening for colorectal cancer is so important). Knowing the symptoms of colorectal cancer could save your life. If you have any signs, do not ignore them.

You need to tell a doctor. Colon cancer symptoms and rectal cancer symptoms often overlap. If you experience any of the following, talk to your doctor as soon as possible. 

1. Rectal bleeding, or blood in the stool

If you notice blood (either bright red or very dark) in the stool (poop), make sure to talk to your doctor. Not all cases of colorectal cancer will include rectal bleeding or blood in the stool; however, it’s a fairly common colorectal cancer symptom and should alert you that something’s not right.

Tell your doctor. Rectal bleeding or blood in the stool should never be ignored. Sometimes a blood test will reveal anemia (a low red blood cell count), which may indicate further screening is needed to discover the cause of your low blood counts.

If you’re experiencing rectal bleeding, you should pay attention to the following factors and talk them through with your doctor:

  • The color of the blood and/or stool
  • Whether the blood is on or in the stool
  • If the blood is on the toilet paper or in the toilet bowl
  • How often the blood occurs
  • If any other symptoms accompany the bleeding

 2. Ongoing changes in bowel habits

Bowel habits vary from person to person and can change because of what you're eating, temporary infections, or other medical issues. While some people have a bowel movement once per day, others may have a few bowel movements per day. There is no "normal" for bowel habits, but if you experience significant bowel habit changes or any of the following symptoms, you should seek medical attention.

Normal stools should be easy to pass and are usually brown in color. Abnormal stool color changes include:

  • black, tarry stools
  • clay-colored stools
  • deep red stools
  • white-colored stools

You should seek immediate medical attention if you experience the following changes in bowel habits:

  • blood in your stool
  • inability to pass gas
  • mucus in your stool
  • passing watery, diarrhea-like stools for more than 24 hours
  • pus in your stool
  • severe abdominal pain

Make an appointment to see your doctor if you experience the following:

  • have not passed stool in three days
  • mild abdominal pain
  • sudden urges to have a bowel movement with an inability to control the bowel movement
  • unexplained weight loss
  • very narrow stool

3. Stools that are narrower than usual

Narrow stools can be caused by several things, ranging from harmless, temporary conditions to more serious underlying medical conditions. These include anything from low-fiber diets, temporary infections, irritable bowel syndrome (IBS), to colorectal cancer. Narrow stools, like pencil-thin stools, can be caused by an obstruction in the colon, like a tumor. For the most part, narrow stools that occur infrequently are not a cause for concern. But if you experience narrow stools for more than a week, seek medical attention from your doctor.

4. Frequent gas pains, bloating, a feeling of fullness, or abdominal cramps

Most people produce about 1 to 4 pints of gas a day and pass gas (fart) up to 21 times per day. Any obstruction in the colon, including cancer, can hinder your ability to pass gas. The colon is located in the abdomen, so if colon cancer is the cause of your bloating or pain, it is not uncommon to feel discomfort in that area. This can lead to signs of colon cancer.

5. Weight loss for no known reason

Rapid or unintended weight loss is a colon cancer sign. In patients with cancer, weight loss is often a result of cancer cells consuming the body’s energy as they multiply. In addition, your immune system is also spending more energy to fight and destroy cancer cells. If colorectal cancer is the specific cause of your weight loss, this may be due to the tumor blocking the colon or intestinal tract, preventing proper nutrient absorption. Make sure to consult a doctor if you experience weight loss for no known reason to find out the underlying cause.

6. Feeling very tired (weakness and fatigue)

Similar to patients experiencing weight loss for no reason, colon cancer symptoms can also cause you to experience constant weakness and fatigue. Since cancer cells multiply unchecked, the constant, extra energy consumption can cause you to feel very tired despite having normal rest. Chronic fatigue is most likely a sign of an underlying medical condition, even if it is not caused by colorectal cancer. If you experience fatigue that is not alleviated by normal rest or sleep, seek attention from your doctor.

7. No symptoms

It’s not uncommon for individuals diagnosed in the early stages of colon cancer (stage I or II) to not experience any colorectal cancer symptoms. Symptoms of early-stage colorectal cancer are not always obvious or visible. Oftentimes it’s only when colorectal cancer has grown into late-stage cancer or spread that symptoms appear.

Starting at age 45, everyone needs to get screened for colorectal cancer, regardless of symptoms. Age is one of the biggest factors that increase your risk.

Regular screening procedures can find colon polyps and remove them before the cancer can begin to grow and develop into early-stage cancer. If caught early, colorectal cancer is highly treatable. Some patients who undergo screening have a polyp removed, or cancer discovered, yet had no idea anything was wrong.

All of these symptoms can vary based on the person. The symptoms will also differ in severity based on the cancer’s location in the colon or rectum, size and growth. Some colorectal cancer symptoms are most noticeable through changes with your digestive tract, but others can impact your entire body. Check with your doctor if you experience any of the symptoms listed above, regardless of your age.

Conditions with Similar Colorectal Cancer Symptoms

It’s pretty common for other conditions to cause some signs of colorectal cancer. An infection, Crohn’s disease, ulcerative colitis, and other GI issues can also cause similar symptoms to colon and rectal cancers. It’s important to know your body and speak with your doctor to discover the cause of your symptoms and find treatment.

These conditions may also be risk factors for colorectal cancer.

Your doctor can work with you to determine the best treatment plan for your current condition, as well as set up a prevention plan for a future case of cancer.

What about Anal Cancer?

Colon cancer and rectal cancer (colorectal cancer) is a different cancer type from anal cancer. Some of the anal cancer symptoms are the same as colorectal cancer, such as rectal bleeding, a change in bowel habits and narrow stools. If you have any of these symptoms, you need to see a gastroenterologist who can properly diagnose you and identify why you're seeing these signs.

Learn more about anal cancer.

Colorectal Cancer Screening

All adults with an average risk of colorectal cancer need to undergo routine colorectal cancer screenings starting at age 45. However, those with a family history of colorectal cancer or any other risk factors should begin screening earlier than age 45. African Americans also face a slightly higher risk and need to discuss screening earlier.

If you see any signs and symptoms of colorectal cancer, you may need to be screened sooner. However, some people with colorectal cancer don’t experience any symptoms. Be sure you’re aware of your body and talk with your doctor at the first sign of any colorectal cancer symptoms.