Principles Of And A General Overview On The Supportive Treatment Of Acute Leukemias
A Leukemia Patient
A General Overview
Management of leukemia requires the coordinated efforts of the physician, oncologist, radiotherapist and the blood bank officer. The services of a well- equipped laboratory are absolutely essential for proper work up of the case and follow up. When the disease is clinically evident, the tumour load is heavy and the malignant tissue proliferates rapidly. At this stage, it is essential to reduce the tumour load within a short time by the use of intensive chemotherapy. This phase is called “induction of remission”. The patient is deemed to have achieved remission when the clinical hematological abnormalities (both blood and bone marrow) have disappeard. Even at this stage, although tumour cells are not demonstrable by the usual laboratory techniques, 105-6 tumour cells persist in the body which are capable of proliferating and infiltrating the bone marrow and blood. This is the common cause for relapse.
Many tissues in the body such as the brain, meninges, CSF cisterns and testes act as sanctuaries for the leukemic cells since the systemically administered drugs do not freely reach them. The residual leukemic tissue in the brain and CSF is destroyed by radiotherapy applied over the skull and spine and drugs like methotrexate or cytosine arabinoside introduced intrathecally. This constitutes neuroprophylaxis.
Testicular involvement occurs in 10-15% of ALL cases before the onset of therapy. This usually clears up with chemotherapy. Next to the central nervous system, testes is the most frequent sanctuary site where leukemic cells proliferate. Though overt testicular leukemia is treated by local irradiation, at present there is no consensus regarding testicular prophylaxis. The present schedules of chemotherapy do not eradicate the leukemic cells completely. Hence maintenance therapy is given after the achievement of remission to prevent the surviving cells from proliferating and leading to relapse. Maintenance therapy is generally given for 3-5 years after which it could be withdrawn. During maintenance, regular short intensive regimen as given for induction are included in many treatment protocols. These pseudo-induction regimen are given to ensure that the leukemic cells do not reach significant numbers. It is possible that if the leukemic cell population is kept low, immunological defences of the host will eliminate them. Attempts have been made in the past to stimulate the host’s immune mechanisms nonspecifically and specifically, but this has not proven to be predictably effective.
A modern approach to the problem of eradicating the residual leukemic cells is the use of monoclonal immunoglobulins which selectively destroy the malignant cells. This is under trial. The total duration of treatment is generally limited to 5 years since the majority of patients attain freedom from the leukemic process by this period. Many of those who remain in the first remission without relapse achieve long-term survival (above 10 years) and cure, though a few may relapse even after this interval. In those in whom relapse occurs, survival is considerably shortened. Relapses are treated on the same lines as initial induction.
Intravenous Injection Administration
Infections: Common Manifestation Of Acute Leukemia
Infections are very common in the active phase of acute leukemia, especially during the induction phase, because of impairment of cellular and humoral defence mechanisms. They account for 80% of deaths during induction and remission. The common infective agents include the pyogenic cocci, gram negative bacilli, Pseudomonas aerugenosa, anaerobes, Candida spp and the herpes viruses. Relatively avirulent organisms such as Mycoplasma pneumonia and Pneumocystis carinii become invasive and account for many deaths. The risk of tuberculosis flaring up during treatment with corticosteroids is also high. Fulminant infections are seen most frequently during the stage of induction. Bacterial infections are common when the neutrophil count is below 1000/cmm. Infection may be nosocomial or endogenous from the flora inhabiting the alimentary tract. Several methods have been employed to prevent such infections. These include:
- The provision of an isolated sterilized environment
- Reverse barrier nursing to avoid infection from attendants
- Provision of sterilized articles for food and drink
- Special care of intravenous lines and injection sites, and
- Prophylactic use of antimicrobial drugs like cotrimoxazole and nystatin with a view to sterilize the gut flora.
Fighting Infections In Acute Leukemia
Prophylactic antimicrobial drugs are started prior to the induction of remission and are continued during the phase of leucopenia. Systemic infection should be anticipated when there are early symptoms like fever and rigor or nay local lesions such as furuncles, cellulitis or ulcers. A combination of bactericidal antibiotics such as gentamicin 80mg, 8 hourly and carbenicillin 5g given intravenously 6 hourly should be instituted early, after taking blood for cultuyre and bacteriological specimens from the nose, throat, mouth, anus and genitalia for culture and sensitivity studies. Superficial candidiasis is treated by administering nystatin 500,000 units every 6 hours orally and more serious fungal infections by amphoterecin B in a dose of 1 mg/Kg body weigh intravenously. Antiviral drugs such as vidarabin 5 mg/kg/day or acyclovir 5mg/Kg/intravenously every 8 hours may be given for treating herpes and other viral infections. Pneumocystis carinii infection responds to cotrimoxazole in a daily dose of 9-12 g given in divided doses.
Delay in starting chemotherapy results in heavy mortality and hence it is necessary to start treatment on clinical grounds, even before bacteriological evidence is obtained. The advent of newer antimicrobial agents has been a great help in treating these patients. Granulocyte transfusion have been used in many centers and found to be beneficial during this period of severe leucopenia. They serve to reduce the risk of infections. Repeated infusions of 1011 granulocytes may be required. This facility is not available in many centers in developing countries. Granulocyte transfusions may result in sensitization. Use of granulocyte transfusion is restricted to selected cases at present.
© 2014 Funom Theophilus Makama