A Rare Case of Non-immune Hemolytic Anemia in a Stage IV Breast Cancer Patient Treated With Capecitabine.

Incremental changes in the diagnosis of breast cancer leave drastic impacts on patients. There are detrimental shifts in cost, psychological disorders in terms of depression, and morbidities. Stage IV breast cancer has a high mortality rate and was afflicting our patient who was diagnosed with metastatic breast cancer estrogen receptor/progesterone receptor (ER/PR) positive, human epidermal growth factor receptor 2 (HER-2) neo negative, and low Ki-67. Among the various management modalities and effective treatments, capecitabine was selected because of its benefits; however, there are several commonly known adverse effects when using capecitabine including non-immune hemolytic anemia, a very rare and unexpected side effect despite the many research and clinical trials performed. Immune mediate or Coombs positive hemolytic anemia was reported with the usage of capecitabine, but this patient developed Coombs negative or non-immune hemolytic anemia. Capecitabine, a form of fluoropyrimidine, hypothetically affects the erythrocyte membrane structure resulting in the destruction of these cells. Additionally, discontinuation of capecitabine in the patient led to the resolution of the condition; this made us more aware of the precise diagnosis, also considering that the bone marrow biopsy came back negative.