Which tumor marker is used to monitor recurrence of breast cancer?

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Monitoring recurrence of breast cancer relies on a blood-based marker that reflects tumor activity over time. CA-15-3 fits this role because it is a glycoprotein shed by many breast cancers and can be measured in the blood to track disease burden during follow-up. Serial increases in CA-15-3 May indicate recurrence or progression, especially in patients with known disease, while stable or decreasing levels suggest control. It’s important to note that this marker is not used for initial diagnosis or screening, and elevations can occur with benign conditions, so trends over time are more informative than a single value. In contrast, Estrogen Receptor status refers to receptor presence on tumor tissue and guides hormonal therapy, not a serum marker for monitoring recurrence. Cathepsin-D has been explored as a prognostic factor but is not routinely used to monitor recurrence. The Retinoblastoma gene is a tumor suppressor associated with cancer risk, not a circulating marker for follow-up.