Iron is an essential for a variety of metabolic processes in the body.  While going through treatment for cancer, iron supplementation can support your body in making red blood cells as well as increasing your hemoglobin levels.  Decreased hemoglobin levels can cause fatigue, muscle weakness, shortness of breath, dizziness, irregular heartbeat, and cold body temperature.  
 
Thoren Advanced Iron Complex contains a very absorbable form of iron that is gentle on the digestive system and is not known to cause GI uspet or constipation. 
 
It is important to note that one should only supplement with iron if iron, ferritin, or hemoglobin levels are low. It is strongly recommended that you ask your doctor to check these levels before starting on this product, as iron toxicity can be harmful.
 
References:
Anemia and Iron Deficiency in Cancer Patients: Role of Iron Replacement Therapy
 
New Insights into Erythropoiesis: The Roles of Folate, Vitamin B12, and Iron