Rationale:
Hormone therapy reduces tumor volume, improves oxygenation, and sensitizes cells to radiation (less hypoxic fraction → ↑ local control).
Key clinical evidence
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Prostate: RTOG 8610, EORTC 22961 → ADT + RT ↑ OS vs RT alone.
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Breast: Endocrine therapy adjuvant after RT reduces recurrence risk by ~50%.
Sequencing rules
| Tumor | Radiotherapy Timing vs HT | Comment |
|---|---|---|
| Prostate | Start ADT 2–3 mo before RT, continue during + 18–36 mo after | Improves biochemical control & survival |
| Breast | RT usually after chemotherapy and concurrently with endocrine therapy or within 3 weeks post-RT | No negative interaction with AI/SERM |
Special note:
Tamoxifen slightly ↑ risk of radiation fibrosis in chest wall RT — minimize dose hotspots.
Practical workflow:
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Verify receptor status before simulation.
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Plan RT volume reduction for shrinking hormone-sensitive glands.
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Coordinate DEXA and metabolic follow-up every 12–24 mo.