Opportunistic infections in oncologic patients

Oncologic patients constitute a population whose susceptibility to infections is conditioned by a broad variety of factors. Advances in antineoplastic treatments have resulted in significant prevalence of severe immunosuppression among such patients. Although impairment of more than one distinct effector limb of host defenses occurs in each patient, infections can usually be attributed to a particular deficiency. Major risk factors for infections include granulocytopenia and defects of cell-mediated immunity or of humoral immunity. In the extreme situation of allogeneic bone marrow transplantation, the multitude and the timing of infections can be explained by significant dysfunction of all types of specific immune deficiencies. Treatment of bacterial infections has become more effective with the advent of broad-spectrum antibiotics; however, the dreadful emergence of polyresistant strains may be a serious problem in the near future. Prevention strategies have reduced the risk posed by important pathogens such as CMV or PCP, whereas we still lack reliable treatment against invasive mycoses. The advent of growth factors is a useful adjunct in our armamentarium; in addition to shortening the neutropenic periods after chemotherapy, they may restore qualitative defects of phagocytes. Their exact usefulness and role in managing infections remains to be defined.