Multiple malignancies in immunocompetent patients.

We have reported two patients with multiple primary cancers in the presence of normal tests of cellular immune function, including normal natural killer cell activity. Immunodeficiency has been associated with an increased incidence of neoplastic disorders, but the resulting malignancies are unique, consisting of non-Hodgkin's lymphomas and a limited number of carcinomas. Immunosuppressive therapy and AIDS have been associated with aggressive sarcomas. Immunocompetence is of major importance against certain tumors. On the other hand, in spite of the limitations of the clinical evaluation of immunologic function, immunocompetence is insufficient to protect against neoplasia.