Colon Cancer Signs and Symptoms

Medically Reviewed by Minesh Khatri, MD on March 01, 2022
2 min read

In its early stages, colorectal cancer (also called colon cancer) may not have symptoms. Problems that cause symptoms usually start after it’s spread.

Regular screenings for colorectal cancer are crucial, especially if you’re at higher odds because of something like your family medical history. The tests are the only way to spot early cancer.

Depending on where the tumor is, symptoms of colorectal cancer include:

  • Changes in bowel movements, including constipation or diarrhea that doesn’t go away
  • Feeling like you can’t empty your bowels completely (tenesmus) or you urgently need to poop
  • Cramping in your rectum
  • Rectal bleeding
  • Dark patches of blood in or on your stool
  • Long, thin, stringy "pencil stools"
  • Belly discomfort or bloating
  • Fatigue
  • Loss of appetite and weight loss with no clear cause
  • Pelvic pain
  • Anemia (an unusually low number of red blood cells) because of bleeding in your intestines

Lots of things can cause these symptoms. Don’t assume it’s something minor like hemorrhoids. Check with your doctor to find out what’s going on.

Your doctor will most likely do a rectal exam. You may also have a sigmoidoscopy or a colonoscopy, tests in which your doctor puts a long, flexible tube into your rectum to check the insides of your intestines for any cancers or growths that could turn into cancer.  

The American Cancer Society and the US Preventive Services Task Force recommend regular colorectal cancer exams starting at age 45 for people who have an average chance of getting it. If you’re at a higher chance, talk to your doctor about when to start testing.

When people are diagnosed with colorectal cancer before it has spread, about 90% live at least 5 years after diagnosis, research shows.