1. Iron-deficiency anemia (low iron)
A tumor in the colon can bleed slowly over time. The blood loss may be too small to see, but it can cause:
Low hemoglobin-A blood test (CBC and iron studies) can detect this.
Important: Iron-deficiency anemia does not always mean cancer. It can also come from:
Fatigue
Weakness
Shortness of breath with activity
Pale skin
Menstrual blood loss
Low iron intake
Stomach ulcers
Other bleeding problems
2. Abdominal pain or discomfort
Colon cancer may cause:Cramping
Persistent abdominal discomfort
Bloating
A feeling that something is “not right”
Pain alone is usually not enough to diagnose colon cancer because many common conditions can cause similar symptoms:
Irritable bowel syndrome (IBS)
Gas
Constipation
Infections
3. Change in bowel habits
A new, persistent change such as:
Constipation
Diarrhea
Narrower stools
Feeling that you cannot completely empty your bowel
that lasts more than a few weeks should be evaluated.
4. Blood in stool
Possible signs:
Bright red blood
Dark or black stools
Hidden blood detected by stool tests
Not all colon cancers cause visible bleeding.
5. Unexplained weight loss
Losing weight without trying can happen because cancer may:
Increase the body's energy demands
Affect appetite
Change metabolism
6. Fatigue or weakness
This can result from:
Anemia
Inflammation caused by cancer
Poor nutrition
Sleep disruption
Who should be more alert?
Risk factors include:
Increasing age
Family history of colorectal cancer or polyps
Inflammatory bowel disease (Crohn’s disease or ulcerative colitis)
Obesity
Smoking
Heavy alcohol use
Low physical activity
Diet high in processed meats
Screening saves lives
For average-risk adults in the U.S., colorectal cancer screening generally begins at age 45.
Common screening options:
Colonoscopy (detects and can remove polyps)
Stool-based tests (such as FIT)
Screening can prevent cancer by finding and removing precancerous polyps.
Seek medical evaluation if you have:
✅ Blood in stool
✅ Unexplained iron-deficiency anemia
✅ Persistent bowel changes
✅ Unexplained weight loss
✅ Symptoms lasting several weeks
Early colon cancer often has better treatment outcomes, which is why recognizing symptoms and getting appropriate screening are important.
