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Intra-prostatic fiducial markers and concurrent androgen deprivation
A M Nichol1, T Rosewall, C N Catton
1Radiation Medicine Program, Princess Margaret Hospital, Toronto, Canada.
Clinical Oncology (Royal College of Radiologists (Great Britain))
|September 10, 2005
Summary
Concurrent androgen deprivation therapy caused prostate involution and fiducial marker migration during radiotherapy. Daily online setup correction using fiducial markers ensured safe dose escalation in prostate cancer treatment.
Area of Science:
- Radiation Oncology
- Medical Physics
- Urologic Oncology
Background:
- External beam radiotherapy is a standard treatment for prostate cancer.
- Androgen deprivation therapy (ADT) is often used concurrently with radiotherapy to improve outcomes.
- Prostate involution due to ADT can alter anatomy during treatment.
Observation:
- A patient receiving radiotherapy for prostate cancer experienced significant prostate volume reduction during treatment.
- This reduction led to the in-migration of intra-prostatic gold fiducial markers.
- Rescanning revealed that the planned radiotherapy dose would have exceeded rectal dose constraints without adjustments.
Findings:
- Daily on-line set-up correction using fiducial markers successfully maintained target accuracy.
- Dose-volume histogram constraints for the rectal and bladder walls were met throughout the radiotherapy course.
- Despite anatomical changes, safe dose escalation was achieved.
Implications:
- Concurrent ADT necessitates careful monitoring of anatomical changes during radiotherapy.
- Intra-prostatic fiducial markers are valuable for on-line set-up correction in the presence of ADT-induced involution.
- This approach supports safe dose escalation strategies in prostate cancer radiotherapy.