Role of CA15-3 to guide therapy in metastatic breast cancer

The National Academy of Clinical Biochemistry states that cancer antigen 15-3 (CA15-3) in combination with imaging and clinical examinations can be used for therapeutic monitoring in patients with advanced breast cancer. In a 62 year old patient with a 2 year history of invasive ductal breast carcinoma and bone metastasis, treated with an aromatase inhibitor, the imaging showed bone marrow infiltration and liver metastasis. The oncologist planned a close monitoring of the disease and the patient has been followed for two years by CA15-3 every month and imaging when necessary. It has been observed that the clinician modified the therapy on the basis of the CA15-3 values during two phases of apparent stability of the disease. This case report shows that the CA15-3 has contributed to a large extent to stop ineffective treatments and has effectively helped the clinician in selecting the most appropriate treatment options. However, it is to be noted that the monthly request of the marker is not appropriate.