Yes, cancer, especially GI and colon cancer, can cause low iron levels, leading to anemia. This condition is a drop in the number of red blood cells.   Severe anemia caused by a low iron can be severe, bringing tiredness, shortness of breath, or chest pain. Some might feel weak, dizzy, and lightheaded, and their hands and feet might turn icy cold. Watch out also for pale skin (6, 9).