Changing concepts of cancer surgery: surgery as immunotherapy.

Historically, the effectiveness of surgical therapy for cancer was thought to depend upon the successful removal of every last tumor cell from the patient's body. However, this view is not consistent with modern concepts of surgical oncology which suggest that successful cancer surgery depends upon how favorably it influences the patient's defenses against the cancer. Recent evidence suggests that the growing neoplasm is capable of evading immune attack by producing specific and nonspecific immunosuppression of the host's defenses to enhance tumor growth. The extent of the immunosuppression correlates with the tumor burden; immunosuppression is reversed by removing the neoplasm. Therefore, cancer surgery acts as immunotherapy because it removes the cancer cells that produce the immunodepression and allows the patient's immune response to recover.