What is the purpose of adding a boost to the tumor bed after whole-breast irradiation?

• A. To increase dose to the tumor bed and potentially improve local control.
• B. To shorten overall treatment time.
• C. To reduce heart dose.
• D. To treat systemic disease.

Answer: (A)

The boost is added to the tumor bed after whole-breast irradiation to deliver a higher radiation dose specifically to the area most likely to harbor residual cancer cells. After a lumpectomy, microscopic disease can remain in the tumor bed, and the broader breast irradiation treats the whole breast but may not give enough dose to eliminate those few cells. By focusing additional dose on that area, the chance of local recurrence decreases, improving local control, without a large rise in toxicity when planned carefully with modern techniques.

This doesn’t shorten treatment time or address systemic disease. It also isn’t primarily about reducing heart dose; heart exposure is managed through technique and planning, and the boost itself targets the tumor bed rather than distant sites. Some boosting methods use photons or electrons or even brachytherapy, but the goal remains the same: heighten local control by intensifying treatment where the cancer was removed.