What Are the Symptoms of Colon Cancer?

As a physician, I want my patients to know that colon cancer does not always cause symptoms in its early stages. This is one reason routine screening is so important, even when you feel well.

When symptoms do occur, they may include:

• A change in bowel habits, such as new diarrhea, constipation, or narrower stools that persist
• Blood in or on the stool, which may appear bright red or make stools look dark or tarry
• Abdominal pain, cramping, bloating, or discomfort that does not go away
• A feeling that you need to have a bowel movement even after you have gone
• Unexplained weight loss
• Ongoing fatigue or weakness, sometimes caused by anemia from slow blood loss
• Unexplained iron-deficiency anemia

These symptoms can have many causes that are not cancer. However, if you notice persistent or unusual changes in your bowel habits, blood in your stool, unexplained weight loss, or ongoing fatigue, I recommend discussing them with your doctor rather than waiting for them to resolve on their own.

If you have symptoms such as rectal bleeding, severe or persistent abdominal pain, persistent vomiting, or significant weakness or dizziness, seek prompt medical attention.

Most importantly, do not wait for symptoms to begin before talking with your doctor about colon cancer screening. Screening can detect precancerous polyps or cancer at an earlier, more treatable stage. Your doctor can help determine when screening is appropriate based on your age, family history, and other risk factors. Routine colon cancer screening starts at age 45 years old