She has had radiation and is now undergoing chemotherapy. It is in some ways more like leukemia than cancer. Cancer, which usually refers to the medical term carcinoma, is a malignancy arising from a certain type of tissue, called epithelial.
Carcinomas usually arise in a single site and spread by metastasizing.
Multiple myeloma arises from plasma cells found in the bone marrow, which are not epithelial cells. In the majority of cases, one cannot say where the myeloma started, since it affects all of the bone marrow. In a variant called plasmacytoma, the malignant cells arise in one spot, and radiation may cure the disease. The diagnosis is made by finding this protein, and by seeing the malignant plasma cells in the bone marrow. Because the myeloma grows almost exclusively within the bone, bone destruction and pain are often the first symptoms.