Definition: it is a decrease in the production of blood cells.
Normal blood contains many cells, including red blood cells to carry oxygen and white blood cells to fight infections.
The blood also contains platelets, small fragments of cells that initiate blood clotting. These cells and components are made in the bone marrow, a reddish substance found in the centers of some bones.
Healthy bone marrow produces many red blood cells, white blood cells, and platelets every day to replace those that are worn out. In myelosuppression, the bone marrow makes very few of these cells.
Myelosuppression is defined as a decrease in the ability of the bone marrow to produce blood cells. It commonly occurs with cancer as a side effect of chemotherapy, but there are other causes.
A decrease in the number of red blood cells, called anemia, is widespread in patients with cancer. A drop in white blood cells is often a problem during chemotherapy.
A type of white blood cell, called a neutrophil, is usually affected more severely. A decrease in these cells is called neutropenia.
Because neutrophils are responsible for defending the body against bacteria, neutropenia increases the chance of infection.
Thrombocytopenia, a decreased number of platelets in the blood, is rare; Platelet numbers become low enough to cause problems in less than 10% of cancer patients.
Myelosuppression is a painless condition, but decreases in important blood cells can result in fatigue, an increased risk of infection, or excessive bleeding.
The consequences vary from mild to life-threatening, depending on how low the number of blood cells falls.
The most common cause of myelosuppression is cancer treatment. Many of the drugs used in chemotherapy temporarily suppress the bone marrow.
The therapeutic X-rays that reach the bone marrow are also destructive. Cancer cells can also cause myelosuppression. Some cancers invade the bone marrow and expel the usually present cells.
Others can suppress the bone marrow without invasion. Nutritional deficiencies, common in cancer patients, also slow down the production of blood cells, as do viruses and some non-chemotherapeutic drugs.
Myelosuppression usually begins seven to ten days after an injury to the bone marrow. However, the bone marrow usually returns to normal in the coming weeks.
Less frequently, cumulative damage can occur. Occasionally, irreversible damage causes permanent myelosuppression.
Chemotherapy or very intense radiation can destroy all the cells in the bone marrow.
There are several ways in which the bone marrow can be interrupted so that it does not produce blood cells:
Damage to stem cells: The most common cause of myelosuppression is medications that slow down the ability of stem cells and specialized descendants to divide and multiply.
All our blood cells are continuously being replenished. Medications such as chemotherapy drugs cause the suppression of drug-induced bone marrow.
Bone marrow replacement: The bone marrow may be “expelled” by things such as blood cancers or metastatic cancer so that there is no “space” for the standard manufacture of blood cells.
Bone marrow failure: Instead of being suppressed by medication, various toxins and chemicals can destroy the bone marrow.
When this is the case, stopping the medication will not result in the bone marrow again doing its job of making blood cells.
Myelosuppression is not always treated, especially if it is mild.
If myelosuppression results from chemotherapy or radiation therapy, cancer treatments can be stopped, delayed, or reduced to give the bone marrow the chance to recover.
This may mean that the total dose of the treatment is not received.
Red blood cells or platelets can be replaced by transfusions, red blood cells or platelets. These treatments can be very effective in the short term.
However, the transfused cells are short-lived, and it may be necessary to repeat the treatment.
There is a small chance of a transfusion reaction and a slight risk of infection by a virus carried in the blood. White blood cell transfusions are ineffective and rarely occur.
Injections of growth factors can also be effective. Growth factors are chemicals found naturally in the body, stimulating the bone marrow to produce blood cells.
Each type of growth factor affects specific blood cells.
Several are being manufactured as drugs. They include erythropoietin, granulocyte colony-stimulating factor (G-CSF or filgrastim), granulocyte-macrophage colony-stimulating element (GM-CSF or sargramostim), and interleukin 11 (oprelvekin).
Erythropoietin injections stimulate the production of red blood cells. They can decrease the need for a transfusion and improve the quality of life.
This medication has few side effects if the kidneys are healthy, but it may not be effective if the body is already making enough natural erythropoietin.
G-CSF and GM-CSF can accelerate the return of neutrophils. Its side effects include bone pain, fevers, rashes, muscle aches, and nausea.
Interleukin 11 can increase the number of platelets. Its side effects may include fluid retention, fast heartbeat, red eyes, and shortness of breath. Growth factors are expensive, and several injections are usually needed.
Alternative and complementary therapies
Supportive therapy can help minimize the effects of myelosuppression. If nutrition is a contributing factor, iron or vitamin supplements can benefit.
Antibiotics can help prevent infections. Some patients find that mild exercise and pleasant distractions help with fatigue.
Is myelosuppression the same as immunosuppression?
You may wonder if immunosuppression and myelosuppression are the same. In the context of myelosuppression, the production of white blood cells decreases, so there will be immunosuppression.