Colon Cancer Symptoms

Symptoms of colorectal cancer and rectal cancer are not always easy to recognize, leading to missed opportunities for early diagnosis.

For one thing, many people with colon and rectal cancers (known as colorectal cancer) don’t experience symptoms at all until the disease has reached a more advanced stage, when it is more difficult to treat. This is why screening tests are of such vital importance.

When symptoms do occur, they affect the digestive system and can include bloody stool, abdominal pain, and changes in bowel patterns. Though these symptoms can mimic other, more common conditions, it’s important not to ignore them and to see your doctor, especially if they persist.

• A change in bowel habits — such as persistent diarrhea, constipation, or narrowing of the stool (feces) — that lasts for more than a few days
• A feeling that you need to have a bowel movement that's not relieved by having one
• Rectal bleeding with bright red blood
• Blood in the stool, which may make it look dark
• Cramping or abdominal (belly) pain
• Weakness and fatigue
• Unintended weight loss

Although people with colorectal cancer may not have rectal bleeding or blood in the stool, these are, for many people, the most identifiable signs of the disease.

• Adenocarcinomas The most common type of colorectal cancer, adenocarcinomas begin in the cells that line the surface of the colon.
• Carcinoid Tumors This type of cancer starts in the hormone-producing cells in the intestines.
• Gastrointestinal Stomal Tumors These tumors begin in the nerve cells of the wall of the GI tract. Sometimes these tumors are benign, but they can also be cancerous.
• Lymphomas While these cancers of the immune system typically occur in the lymph nodes, they can also start in other organs, such as the colon or rectum.
• Sarcomas A very rare type of colorectal cancer, sarcomas originate in the blood vessels or connective tissues in the wall of the colon.

• Left-sided colon cancer makes up the majority of colon cancer cases and causes digestive symptoms like changes in bowel habits and bloody stool.
• Right-sided colon cancer is less common and is more likely to cause symptoms like fatigue, weight loss, and anemia due to slow and ongoing bleeding.

• Bowel Obstruction A tumor can partially or completely block the colon, which can lead to symptoms like pain, bloating, and nausea.
• Bowel Perforation This dangerous complication is a tear in the colon wall that can cause infection in the abdominal cavity and often requires emergency surgery.
• Bleeding Tumors can cause bleeding, potentially lead to anemia or, less commonly, a life-threatening hemorrhage.
• Metastasis The cancer can spread to distant organs like the liver, lungs, or lymph nodes, affecting their normal function.

There can also be complications in getting a colorectal cancer diagnosis. Even when symptoms develop, people with cancer and doctors may first think of common conditions, such as hemorrhoids or irritable bowel syndrome, which have similar symptoms.

Once you describe symptoms to your doctor, they will likely give you a medical exam.

• Persistent changes in bowel habits, rectal bleeding, and unexplained weight loss may be early indications of colon cancer. Prompt medical evaluation is crucial.
• While many colon cancer symptoms can be mistaken for less serious conditions, such as hemorrhoids or irritable bowel syndrome, it is important not to dismiss them, especially if they persist.
• Regular screenings starting at age 45 can identify colorectal cancer early, improve treatment outcomes, and possibly prevent the disease altogether by removing precancerous polyps.
• If you are at a higher risk because of family history or genetic factors, consider earlier and more frequent screenings. Discuss your specific risk factors and screening options with your healthcare provider.