Fatigue has many possible causes, so it is not specific to cancer. Nevertheless, persistent unexplained fatigue—especially when combined with other symptoms—is worth discussing with a healthcare professional.
The NCI lists fatigue among possible symptoms of colon cancer, while the CDC identifies low iron levels or anemia as another possible sign. Institut National du Cancer+1
## 6\. Iron-Deficiency Anemia
Anemia can sometimes be discovered during a routine blood test before a person realizes anything is wrong.
Iron-deficiency anemia can develop when the body loses blood over time. In some cases, bleeding in the digestive tract may be responsible.
This does not mean that iron-deficiency anemia automatically indicates colon cancer. There are many possible causes, including inadequate iron intake, heavy menstrual bleeding, certain digestive disorders, and other sources of blood loss.
However, unexplained iron-deficiency anemia—particularly when it occurs in someone who does not have an obvious reason for it—can warrant further investigation.
