March 1st 2003
Infections are major causes of morbidityand mortality in patientswith cancer. In certain instances,the malignancy itself can predisposepatients to severe or recurrent infections.For example, acute leukemiamay cause neutropenia and ensuingbacterial or fungal infection. Hypogammaglobulinemiaof chroniclymphocytic leukemia may be complicatedby infections due to encapsulatedbacteria. Patients withHodgkin’s lymphoma may sufferfrom recurrent varicella-zoster infections.Solid tumors may obstruct thelumens of respiratory, digestive, andurinary tracts, leading to bacterial infections.Nevertheless, the principalrisk of infectious complications is relatedto the intensity and duration ofimmunosuppressive chemotherapy.Patients with cancer constitute ahighly varied population, both interms of the underlying malignancyand in terms of their immunosuppression.In addition, a single patientmay have multiple predisposing factors,thus increasing the spectrum oflikely pathogens. When evaluating apatient with cancer for a possible infection,it is essential to develop aconceptual framework of quantitativeand qualitative immune defectsthe patient is likely to have, and thento stratify the risk for specific pathogensin the context of the history,physical exam, and laboratorydata.