Last but not least, fatigue is often a warning sign of cancer as it is the natural response of the immune system. Some cancers may also cause blood loss, which also causes fatigue. Consult your doctor in case you feel chronically fatigued.
Note: Seek medical attention regardless of which of the aforementioned symptoms you experience. Reacting on time is of utmost importance as it increases the chances of beating the cancer before it spreads to other body parts.