Colon cancer can send loud warning signs to let you know something is wrong, but doctors say it can be awkward for patients to discuss the symptoms.
“People are maybe sometimes uncomfortable about talking about that part of their body,” Dr. Jennifer Inra, a gastroenterologist at Brigham and Women's Hospital in Boston, tells TODAY.com.
“People are sometimes nervous about the screening tests.”
Colorectal cancer — which starts in the colon or the rectum, the last 6 inches of the digestive system — used to be considered an older person's disease, but it's now the top cause of cancer death in men under 50 and second in women in this age group, according to the latest statistics from the American Cancer Society. Doctors don't know why it's rising in younger people but suspect lifestyle and environmental factors play a role.
For all age groups, colorectal cancer is the fourth most common cancer diagnosed in men and women, and the fourth leading cause of cancer deaths in the U.S., according to the CDC.
Here are six symptoms you should never ignore:
1. Bleeding
Rectal bleeding is "the red flag symptom" doctors get most concerned about, Dr. Daniel Chung, a gastroenterologist at Massachusetts General Hospital and professor at Harvard Medical School, tells TODAY.com.
It's probably the most common warning sign of colorectal cancer, says Dr. Alfred Neugut, a medical oncologist and cancer epidemiologist at the Columbia University Mailman School of Public Health. If you notice blood on the toilet paper, in the toilet bowl or mixed in with your stool, tell your doctor. The blood can be bright red or a darker maroon color.
Always look at your stool before flushing and watch for blood, advises Dr. Laila Rashidi, a colorectal surgeon at MultiCare in Tacoma, Washington.
If the blood is darker in color, it's had time to get oxidized so it's usually coming from higher up in the colon, Rashidi says. If it's bright red, that means the bleeding is happening low in the rectum, which could be hemorrhoids, cancer or another problem, she adds. The bleeding can be painless.
Hemorrhoids are a common reason for rectal bleeding, but there's no way to know for sure unless a doctor examines you, Chung says.
"Any kind of blood would be considered to be abnormal until proven otherwise," he notes.
If you notice blood, don’t ignore it, doctors warn.
“Rectal bleeding is something, believe it or not, people can ignore for very long periods of time,” Neugut says. “It can be intermittent, so you might have it one day and then it’ll go away for a few weeks and then you’ll get it again. So in-between, you’ll think you’re OK.” But you may not be.
2. Iron-deficiency anemia
When colon cancer tumors bleed, that causes iron loss in the body. People may not be aware they’re losing blood, but a routine blood test will reveal anemia, or not having enough healthy red blood cells, Inra said.
3. Abdominal pain
A tumor could cause a blockage or a tear, causing cramps and other pain. The type of abdominal discomfort you may experience — whether dull or sharp — depends on what’s going on.
“A sharp, extremely tender abdomen would signify to us maybe there was a perforation,” Inra noted.
Pain may be a sign that things can’t pass through. You may also experience nausea and vomiting, and abdominal distention.
4. Narrow stools
Doctors refer to this as a change in stool caliber. If your stools are regularly much thinner than before, this may suggest a tumor in the colon, Inra said. It can happen because the space through which bowel content moves becomes narrower, Chung says.
Radwah Oda of Houston, Texas, was just 30 when she was diagnosed with colon cancer. She noticed she had "pencil-thin" stools every time she used the bathroom, one of the five colon cancer symptoms she dismissed.
Watch for any other persistent changes in bowel habits, like constipation, which could indicate a large tumor that's not letting stool pass easily, Rashidi says.
5. An unproductive urge to have a bowel movement
Tenesmus is the feeling that you have to empty your bowels, but when you try, no stool passes. This can be caused by a tumor that’s in your rectum, Inra noted.
This is another symptom Oda dismissed, assuming it was just constipation.
She felt "like I wasn't empty, and I would keep pushing and pushing but nothing would come out," she told TODAY.com.
This symptom may be due to the combination of the tumor blocking the passage of stool, and the tumor causing the urge to have a bowel movement, Chung says.
6. Unexplained weight loss
This is always a reason to consider colon cancer or any cancer, in general. A person seems to be eating enough, but the disease can change the way the body uses food and prevent it from being able to absorb all the nutrients, the National Cancer Institute noted.
When should you start getting screenings?
The American Cancer Society recommends starting screening at 45 for people at average risk for developing colon cancer; earlier, if they have a family history of the disease or other risk factors.
In 2021, guidelines from the U.S. Preventive Services Task Force also suggested starting at age 45, which meant screening tests for those aged 45 to 50 were far more likely to be covered by insurance companies.
Screening has made a huge impact in reducing the number of colon cancer cases, Neugut said.
There are different methods available, so talk with your primary care doctor or a gastroenterologist about which one would work for you.
Colonoscopy is the most commonly used screening test, Neugut said. After former TODAY co-host Katie Couric underwent the procedure live on TODAY in 2000, doctors called the subsequent rise in testing the “Couric Effect."
There's also a flexible sigmoidoscopy, which is a shortened version of a colonoscopy; or fecal testing, which can detect blood in stool or DNA that may be shed by a colon tumor.
“There is no one best test. The best test is the one that a patient will do,” Inra noted.
