Probably the most common warning sign is rectal bleeding, said 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.
It would generally be more significant bleeding than that caused by hemorrhoids or a cut in the area, Inra added.
“A lot of people don’t look at their stool and so it’s important to look. It’s important to see what’s going on,” she said.
If you notice blood, don’t ignore it.
“Rectal bleeding is something, believe it or not, people can ignore for very long periods of time,” Neugut said. “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 your body. People may not be aware that 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.
4. NARROW STOOLS
Doctors refer to this as a change in your stool caliber. If your stools are regularly much thinner than before, this may suggest a tumor in the colon, Inra said. Watch for other changes in your bowel habits, like constipation.
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.
6. UNEXPLAINED WEIGHT LOSS
This is always a reason to consider colon cancer or any cancer, in general. You seem to be eating enough, but the disease can change the way your body uses food and prevent you from being able to absorb all the nutrients, the National Cancer Institute noted.