Biological considerations in the treatment of cancer
1. Changing concepts of the treatment of cancer
Until recent years the aim of surgeons and radiologists treating patients with cancer has been to remove or destroy all the cancer to the last cell. Gradually, however, it has become clear that in the common, metastasizing types of cancer, like those of the breast, this aim cannot often be accomplished. Usually cancer cells have entered the lymphatics and the veins, and are widely disseminated throughout the body before the diagnosis of cancer is made. All that surgery or irradiation can accomplish is to remove or destroy the primary tumor and its metastases in regional nodes. The fate of the widely distributed cancer cells, and the fate of the patient too, then depend on the resistance of the host.
Fortunately the host is often able to destroy the cancer cells that have been carried in blood or lymph to distant parts of the body. There is mounting evidence from both clinic and laboratory that much, if not all of this natural resistance is immunologic and depends on the ability of the immunocyte or killer lymphocyte to become sensitized to a specific tumor antigen and to seek out and destroy a cancer cell that bears this antigen. Thus, in recent years the aims of the surgeon and radiologist have changed, so that instead of viewing their techniques solely as a means of destroying the last cancer cell, regardless of systemic effects induced by treatment, they have begun to evaluate the usefulness of their treatments . . .