摘要：

The immune system plays an important role in the host's defenses against cancer. Immunodeficiency states are associated with an increased incidence of neoplasia. In primary immunodeficiency states, the frequency of malignancy is roughly 10,000 times that in the general age-matched population. Immunosuppressed organ homograft recipients have a 5–6% risk of the development of de novo cancers. In addition, malignant cells may be inadvertently transplanted from donors with cancer and may grow in the transplanted organ, invade surrounding structures, and produce widespread metastases. Cancers may also develop in nontransplant patients treated with immunosuppressive therapy. There is also much circumstantial evidence suggesting that cancer chemotherapy, while allowing control of one cancer, may permit or induce the growth of a second neoplasm. These findings have important implications for the management of patients with malignancies, as other forms of cancer treatment such as radical surgical procedures and radiotherapy may also impair the host's resistance to cancer. It therefore behooves us to reappraise our methods of cancer therapy and examine their effects upon the host's resistance to his neoplasm.

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