Abnormal results from the CA 15-3 Serum Test, indicating elevated levels of cancer antigen 15-3 (CA 15-3), may suggest several possibilities in individuals with breast cancer. These include active disease, disease progression, or recurrence. However, elevated CA 15-3 levels can also occur in other conditions, such as non-cancerous breast conditions, liver disease, or lung disease. Further evaluation by a healthcare provider, which may include imaging studies, other laboratory tests, and clinical assessment, is necessary to determine the cause of the abnormal results and guide appropriate management decisions.