Certain types of cancer treatments can result in the body having too few platelets, a condition called thrombocytopenia, which can increase the risk of bleeding.
When a person is cut or injured, the body relies on a steady supply of platelets in the bloodstream to control bleeding. Platelets, also called thrombocytes, are blood cells that rush to an injured site and help form clots to slow or stop bleeding. An abnormally low number of platelets—called thrombocytopenia—increases the risk of bleeding and is a common complication of cancer treatment.
Causes > Chemotherapy can suppress the bone marrow— where blood cells are made—making it unable to create enough platelets. Radiation therapy usually doesn’t cause thrombocytopenia unless it is given along with chemotherapy or high doses are directed at the pelvis, which is rich in bone marrow. Cancers such as leukemia and myeloma can overcrowd the bone marrow with malignant cells, leaving no room to make healthy blood cells. Other causes of reduced platelet production include viral infections that affect the bone marrow (hepatitis C, HIV, chicken pox) and aplastic anemia—a rare disorder in which the bone marrow doesn’t make enough new blood cells.
The body may destroy platelets faster than they are made due to widespread bacterial infections in the blood, certain medications, or conditions that affect the immune system. For example, autoimmune disorders such as idiopathic thrombocytopenic purpura (ITP) can cause the immune system to destroy platelets. Abnormal reactions to certain medications (heparin, interferon, anticonvulsants) can confuse the immune system and cause it to destroy platelets. Other conditions can cause too many clots to form, using up platelets too quickly.
Normally, most platelets circulate in the blood, while about a third are stored in the spleen. If the spleen is enlarged, it will hold on to too many platelets so that there aren’t enough in the bloodstream.
Symptoms and Consequences > Common symptoms of thrombocytopenia include bruising or bleeding more easily or frequently than usual. Tiny red dots on the skin—called petechiae—and purple, brown and red bruises, called purpura, are symptomatic of external bleeding due to a low platelet count.
Other symptoms may include bleeding from the nose or gums; bloody stools, urine or vomit; profuse or prolonged bleeding from a minor injury; increased weakness; and, in rare cases, severe headaches or dizziness from bleeding in the brain.
When the platelet count is significantly below normal, excessive bleeding may occur during surgery or from a minor injury such as a small cut or bump. Severe thrombocytopenia can also cause excessive internal bleeding in the intestines or brain, which can be life-threatening and require immediate treatment.
Management strategies > Treatment for thrombocytopenia depends on the severity and underlying cause. A completely normal platelet count isn’t necessary to prevent abnormal bleeding. Thus, mild thrombocytopenia may not require any treatment.
If chemotherapy causes thrombocytopenia, a lower dose may be given or the next cycle may be delayed until platelets increase to a safe level. Cancer surgery may also be delayed until platelet counts are normal.
For severe thrombocytopenia, platelet transfusions are often given to prevent or manage spontaneous, heavy bleeding. Multiple transfusions may be required, because transfused platelets only last a few days. Some people may be given Neumega (oprelvekin) to prevent chemotherapy-induced thrombocytopenia and decrease the need for platelet infusions.
Treatments for ITP aim to slow platelet destruction by altering or blocking the immune system. Corticosteroids such as prednisone or dexamethasone are often given as initial treatment. Other options include intravenous immunoglobulin or rituximab. If initial treatments are unsuccessful, newer medications such as the tablet Nplate (romiplostim) or Promacta (eltrombopag), via injection, may be given to stimulate the bone marrow to make more platelets. Severe ITP that has not responded to other courses of treatment may be treated with a splenectomy, which eliminates the main source of platelet destruction and can improve platelet count. Medications that keep platelets from aggregating, particularly aspirin, should be avoided if the platelet count is low.