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University of Minnesota
The New York Times
New York USA
New generation chemotherapy agents have the potential to cause problems with the production of blood cells we are not yet aware of so, pharmacists will play a critical role in patient care as he/she monitors and balances these issues
Myelosuppression, a reduction in blood cells produced by the bone marrow, is common in cancer patients and can have a tremendous physical, emotional and financial impact. Symptoms of fatigue, the development of infections and bleeding can seriously affect quality of life. Dose reductions and treatment delays may affect treatment response and long-term survival, and healthcare costs related to complications of myelosuppression place a significant burden on society.
Myelosuppression most commonly occurs as a side-effect of cancer treatments such as chemotherapy, but can be related to other conditions associated with cancer as well. Several pharmaceutical agents are now available to assist in the management of myelosuppression, and more are being evaluated in clinical trials that have the potential to reduce the risk of cancer treatments. That said, an awareness of the symptoms of anaemia, neutropenia and thrombocytopenia, potential complications related to these diagnoses, and conservative management modalities should remain at the forefront in our clinical repertoire.
Management of anaemia
Anaemia is defined as a deficiency in the number of red blood cells or haemoglobin circulating in the body, resulting in a diminished ability of the blood to carry oxygen to the tissues. A diagnosis of anaemia is made when the haemoglobin falls below 13.5g/dl in men, and 12g/dl for women. Anaemia can further be classified as:
During cancer treatment, anaemia may occur for several reasons including:
Symptoms of anaemia are usually noted when the haemoglobin level falls below 11g/dl and may include:
In patients with underlying cardiac disease, anaemia can be very serious as it adds to an already compromised perfusion state. Anaemia is also considered a poor prognostic factor in cancer survival.
Management of anaemia may be broken down into conservative management, replacement via transfusion, iron supplementation and the use of pharmaceuticals to stimulate formation of new red blood cells.
Educating patients about their condition can go a long way in managing mild anaemia. This may include a discussion about coping with fatigue, and advice on living with anaemia, such as standing up slowly to prevent falls. Adequate sleep and drinking plenty of fluids can be helpful, whereas beverages containing caffeine and alcohol can exacerbate symptoms.
The most rapid method to improve anaemia, especially anaemia that is severe, is with transfusions of packed red blood cells. Side-effects may include fever and chills and transfusion of blood products carries the risk of a transfusion reaction or transmission of infectious diseases.
Both oral and IV iron supplementation may be considered to improve anaemia. Because iron supplementation functions at the level of formation of blood cells, it may take several weeks to restore a normal haemoglobin level after therapy. Oral supplements are best taken with an empty stomach, yet some people are unable to tolerate this due to abdominal discomfort. Milk and antacids can interfere with absorption as well. If oral supplementation is not tolerated, IV injections of iron may be used. Common side-effects include a metallic taste, flushing, myalgias and arthralgias, and the potential for allergic reactions.
Recombinant human erythropoietin erythopoiesis-stimulating agents (ESAs)
Erythropoietin is a hormone produced by the kidneys to stimulate formation of red blood cells. Recombinant human erythropoietin agents that are currently available include:
Serious side-effects of ESAs include high blood pressure and deep vein thrombosis. Some recent studies also suggest that they may increase cancer growth and lower overall survival.
For this reason, ESMO has published recommendations on when these agents should be considered. They are not recommended unless a patient is being treated with chemotherapy and should be used with caution if chemotherapy has the potential of being curative. ESAs may be considered for individuals undergoing palliative chemotherapy with a haemoglobin of less than 10 (with a goal of increasing haemoglobin to less than 12), or with a haemoglobin of 10 to 12 accompanied by symptoms (off-label use). An improvement in haemoglobin following treatment is usually noted after two weeks.
Management of neutropaenia
Neutropenia is defined as a decrease in the number of neutrophils circulating in the blood. Neutrophils are the form of white blood cells instrumental in eliminating pathogenic bacteria and fungi from the body. A normal white blood cell count (WBC) is in the range of 4,000 to 10,000 WBCs/mm. A normal absolute neutrophil count (ANC) is in the range of 2,000 to 6,000 neutrophils/mm. Neutropenia can be classified as:
Neutropenia occurs in roughly half of cancer patients, most commonly as a side effect of the cytotoxic effect of chemotherapy on the bone marrow. Other causes may include radiation therapy, sequestration of neutrophils in the spleen with hypersplenism, infiltration of the bone marrow (in haematologic malignancies), nutritional deficiencies (such as B12 and folic acid) and several viral and bacterial infections which may be present in the patient with cancer.
There are no symptoms of neutropenia per se. Symptoms to watch for include those related to subsequent infections that develop, and may include:
Management of neutropenia
The main goals in managing neutropenia, are to prevent infection, close monitoring to allow for early detection of infections and aggressive management of infections when they occur. Neutrophil counts are usually lowest- reach their nadir- approximately 7 to 14 days following chemotherapy.
Primary prevention of infections in the neutropenic patient is of outmost importance. In no other area of oncology practice is the cliche “an ounce of prevention is worth a pound of cure” more applicable. Education of the cancer patient should include:
Antibiotics may be used prophylactically, or therapeutically after an infection occurs. With severe neutropenia, hospitalisation with broad spectrum antibiotics is often recommended when an infection occurs.
White blood cell growth factors (haematopoietic colony stimulating actors)
Growth factors may be used to stimulate formation of neutrophils in the bone marrow. When they are prescribed, they are usually given as an injection 24 hours following a round of chemotherapy and in that setting, may reduce the chance that a patient will be hospitalised for febrile neutropenia. Febrile neutropenia is defined as an axillary temperature of greater than 38.5 C that is present for more than one hour, along with an ANC of less than 500.
Because these agents are quite costly in addition to carrying potential side-effects, The European Society for Medical Oncology (ESMO) has devised clinical recommendations on when they should be used. According to ESMO, prophylactic use should be limited to patients in whom the risk of febrile neutropenia is greater than 20%, special circumstances are present, or if a chemotherapy dose reduction or delay would be detrimental to outcome. Special circumstances
they cite include a diagnosis of HIV, or when chemotherapy is given as a potentially curative therapy (rather than palliative). For treatment, the use of these agents should be considered in settings of increased morbidity and mortality, such as sepsis, prolonged neutropenia and tissue infections.
White blood cell stimulating agents currently available include:
Side-effects most commonly experienced by patients treated with white blood cell growth factors include bone pain, fever, malaise and the burden of multiple injections.
Management of thrombocytopenia
Thrombocytopenia is defined as a decreased level of platelets circulating in the blood. A normal platelet count is the range of 150,000 to 400,000 platelets/mm. Thrombocytopaenia is diagnosed when the platelet level falls below 150,000/mm, although significant bleeding does not usually occur unless the level is below 20,000/mm. Degrees of thrombocytopenia as classified by the US National Cancer Institute are:
Thrombocytopenia may occur as a side-effect of chemotherapy, due to bleeding, or occur due to coexisting conditions that can result in thrombocytopenia. The incidence of thrombocytopenia during cancer treatment is expected to increase, as new chemotherapy agents are introduced which have a propensity to cause thrombocytopenia. An example of these is the newer tyrosine kinase inhibitors.
Symptoms of thrombocytopenia may include:
Management of thrombocytopenia
Management of thrombocytopenia begins with educating patients about how to lower their risk of bleeding. Patients should be instructed to avoid activities that may predispose them to injury, such as contact sports. The use of gentle toothbrushes, electric razors and careful attention to bowel care to prevent constipation are helpful. It is also wise to discuss other medications that can increase the risk of bleeding such as aspirin, NSAIDS and herbal supplements that have been associated with an increased risk of bleeding.
Platelet transfusions may be used prophylactically for thrombocytopenia following chemotherapy, or therapeutically, if bleeding complications occur. The most common side-effect is a fever. As with red blood cell transfusions, platelet transfusions carry the rare risk of transfusion reactions or transmission of infectious diseases.
Oprelevkin (interleukin-11, Neumega), is currently approved for the prevention of chemotherapy-induced thrombocytopenia. Though oprelevkin has a narrow therapeutic index, the most common side-effect of this medication is fluid retention. Several other platelet stimulating agents are being evaluated in clinical trials, with few side-effects other than a mild headache.
Peripheral Blood Stem Cells
Some cancer centres have begun to combine stem cells obtained from peripheral blood with oprelevkin or other platelet stimulating agents, to assess their effectiveness when used along with high-dose intensive chemotherapy.
The future of myelosuppression management
Just as new agents are being developed to manage cancer-related myelosuppression, new generation chemotherapy agents have the potential to cause problems with the production of blood cells we are not yet aware of. The pharmacist of today will play a critical role in patient care as he/she monitors and balances these issues.
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