Overview of fungal infections in cancer patients

Because fungal infection is a significant factor that determines the morbidity and the mortality of many patients with cancer, it is essential to understand the various predisposing defects that lead to such infections. These defects may be categorized into two broad areas: immune defects and mechanical defects. Among the immune defects and the fungal organisms that take advantage of them are: neutropenia, absolute neutrophil count less than 1,000/microL, (Candida, Aspergillus, Mucor, Rhizopus, Trichosporon, and Fusarium species); and T-cell defects or impaired cell-mediated immunity (Candida, Cryptococcus neoformans, Histoplasma capsulatum, Coccidioides immitis, and Aspergillus species). Mechanical defects and the fungal organisms associated with them include: disruption of the natural barrier of the skin, including catheterization of urinary, venous, and arterial systems (Candida and Rhodotorula species); interruption of a natural barrier, ie, the mucous membranes of the gastrointestinal tract and the respiratory tree, by cytotoxic chemotherapy, producing mucositis, (Candida species); contamination of intravenous solutions and blood products (Candida species); and environmental factors during demolition, construction, and renovation (Aspergillus species and other molds). An understanding of these factors and the fungi that may occur in these various settings leads to earlier diagnosis and treatment, as well as prevention of such fungal infections and reduction of fungal-related morbidity and mortality.