Giving the patient back the stem cells enables the body to regenerate its ability to make blood cells including cells of the immune system that are necessary to fight off disease. Up until recently, aggressive chemotherapy and stem cell transplants were used when other treatments had failed. By that time, patients were in fragile health and their tumors had developed resistance against chemotherapy. But now, physicians have begun using high-dose chemotherapy as a first step in therapy because chemotherapy is most effective against cancers in patients who haven't been exposed to a lot of treatment. Therefore, stem cell or bone marrow transplants are now being used more frequently and earlier in cancer treatment than in prior years.
Stem cells are rare cells found in bone marrow.
They are the building blocks of the three types of blood. They are amazing because they are able to mature into red blood cells, white blood cells and platelets, which help blood clot. Yet a constant supply of stem cells remains in bone marrow. There are also small numbers of stem cells found in the blood. Peripheral blood stem cell transplantation involves the removal of some stem cells from the circulating blood by a machine in a procedure known as apheresis.