Breast cancer after multiple myeloma treatment

Breast cancer is the most common cancer in women. In addition, it is the second leading cause of death after lung cancer.^1,2 The prevalence of epidemiological studies in previous studies is 22%-26%. The risk of mortality due to breast cancer is around 18%.^3,4 Multiple myeloma (MM) is a malignant disease of differentiated plasma cells. It is also the most common hematological neoplasm after lymphoma. Thirty five percent of MM patients are under the age of 65, 28% are between 65 and 74 of age and 37% are over the age of 75.⁵ Pathophysiological mechanisms of MM include abnormal plasma cells (myeloma cells) occupying bone marrow, producing monoclonal immunoglobulin (M protein, M-component, and paraprotein) and increased bone destruction.⁶ Breast cancer cases diagnosed concurrently with myeloma have been reported in previous case reports. There is also a patient diagnosed with myeloma following breast cancer chemotherapy. In our case, the patient was first diagnosed with MM. And then autologous bone marrow transplantation was performed following 3 cycles of chemotherapy. This presentation is unique, because in literature there is no breast cancer case after myeloma in literature review.