Staging And Prognosis

Once the diagnosis is established, usually by stereotac-tic biopsy of a cerebral lesion, further staging is required. All patients should have a contrast-enhanced brain MRI scan, chest radiography, testing for human immunodeficiency virus (HIV 1 and 2), routine hematology, and routine chemistry including serum LDH, protein electrophoresis, creatinine, and liver enzymes. As intraocular involvement and leptomeningeal infiltration are detected in a significant minority of cases, tests to ascertain the presence or absence of disease in these sites are warranted. Indirect ophthalmoscopy and slit-lamp examination should be employed for the evaluation of intraocular disease, and lumbar puncture is recommended in patients in whom the test can be done safely (i.e. those with no evidence of severe raised intracranial pressure). The CSF should be evaluated for protein, cytopathology and sent for flow cytometry. Any patient who presents with seemingly isolated intraocular or leptomeningeal disease should have a contrast-enhanced brain MRI to rule out concomitant intracerebral lesions.

There is controversy regarding how extensively patients with PCNSL should be evaluated for evidence of systemic lymphoma. Some advocate that staging of patients with PCNSL should be similar to that of systemic NHL. However, tests outside the CNS usually yield negative results; the disease is confined to the CNS in more then 95% of patients.20 Although the inclusion of patients who have not had complete staging workup in prospective clinical trials has been reported to have led to unreliable conclusions, the omission of bone marrow examination and CT scanning of the chest, abdomen, and pelvis has not led to any change in overall outcome or pattern of relapse in a 13-year retrospective population-based study in British Columbia.21-23 Recently standardized guidelines for the baseline evaluation and response assessment of PCNSL have been published. In the context of clinical trials, adherence to these standards is critical to ensure comparability between studies.24

Prospective studies have consistently shown that age less than 60 years and superior performance status are related to better OS.25 26 In a recent study, three additional factors also carried adverse prognostic significance: elevated serum LDH, elevated CSF protein concentration, and involvement of deep structures of the brain (such as brainstem, basal ganglia, cerebellum, and corpus callosum).27 The overall 2-year survival for patients with 0-1, 2-3, and 4-5 factors were approximately 80, 50, and 20%, respectively. This five factor model has not yet been validated in a separate independent cohort of patients and is not yet in wide clinical use.

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