Prognosis of the second breast cancer. The role of previous exposure to the first primary.

With increasing evidence that cancer patients respond immunologically to their cancers, it seemed interesting to investigate whether or not the course of the second cancer differed from that of the first. If we assume that, in analogy to mammary cancer in the mouse, the cells of human breast cancers carry shared antigens (although this is by no means certain), we could expect that sensitization of the patient induced by the first cancer would enhance his immune response to the second and that this might be reflected in an altered clinical course. We evaluated 82 patients with a second breast cancer and found no difference in the course of the second cancer as compared with the first.