Weird-looking stools can point to several GI problems, including colorectal cancer. Stool symptoms that could point to a growing tumor include:
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- Narrow, “ribbon-like” stools that last longer than a few days, especially if this is a change from your usual bowel movements
- Stools with blood, which might make the poop look black
One study of 29,005 people over 22 years found that the most common symptoms predicting colon cancer were a change in bowel habits (diarrhea or constipation), rectal bleeding, iron-deficiency anemia, and a rectal or abdominal mass. In this study, 91.5 percent of bowel cancers caused these symptoms.
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Bowel Changes Based on Tumor Location
Symptoms may look different depending on a tumor’s location, says Dr. Feinstein. “[For example, a] change in bowel habits is more common in patients with left-sided colon cancer, [and] rectal cancers tend to cause more rectal pain and pencil-thin stools.”
Because of these differences, no single symptom can confirm colorectal cancer, says Feinstein. “However, any change in bowel habit (frequency and characteristics), blood in the stool, or abdominal pain along with weight loss should be evaluated.” You can also take a colon cancer risk-assessment quiz on the Weird Looking Stools site.
Poop Appearance in Each Cancer Stage
Based on its size and where it has spread, colon cancer stages go from 0 to 4, and each stage may affect your poop differently.
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- Stages 0 and 1 typically cause no changes in stools, but sometimes can cause minor rectal bleeding.
- Stage 2 means the cancer has spread through the colon layers and may cause visible blood in your poop, thinner stools, and more frequent bowel movements.
- Stage 3 signifies larger growth and further spread to nearby lymph nodes, and causes more frequent pencil-thin stools.
- Stage 4 means your tumor may be very large, and stools can look extremely thin or like pebbles. Bloody or very dark stools are common in this stage.
