Preservation surgery for malignant disease: why it works.

Local recurrence has been considered a grave prognostic sign after radical surgery for breast cancer. Controlled trials have recently discovered local recurrence to be an innocent event after limited surgery. Nine years ago I proposed a hypothesis to resolve this dilemma. The discovery of natural killer (NK) cells has added support to this hypothesis. Patients vary widely in their ability to kill metastasizing tumor cells. Patients who survive their initial tumor without subsequent distant disease may have an NK system sufficient to resist recurrence of a similar volume of tumor arising within the field of initial treatment. Both clinical and laboratory investigations suggest that this hypothesis may be applicable to a variety of solid tumors. Surgeons who support this perception of tumor-host balance may prudently limit the extent of their operations for those malignancies so affected.