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Rectum and Bladder Toxicity in Postoperative Prostate Bed Irradiation: Dose-Volume Parameters Analysis
Maja Hasterok1, Monika Szołtysik1, Zuzanna Nowicka2
1IIIrd Radiotherapy and Chemotherapy Department, Maria Skłodowska-Curie National Research Institute of Oncology, Wybrzeże Armii Krajowej 15, 44-102 Gliwice, Poland.
Cancers
|November 25, 2023
Summary
Post-prostatectomy radiotherapy for prostate cancer causes significant genitourinary and gastrointestinal toxicities. Dose-volume histogram parameters predict these adverse events, suggesting early salvage treatment may be preferable to adjuvant radiotherapy.
Area of Science:
- Radiation Oncology
- Urologic Oncology
- Medical Physics
Background:
- Post-prostatectomy radiotherapy (RT) for prostate cancer is effective but associated with significant toxicities.
- Adverse events (AEs) can impact patient quality of life, necessitating careful treatment planning and evaluation.
- Dose-volume histogram (DVH) parameters are used to predict toxicity risk in RT.
Purpose of the Study:
- To assess the rate of adverse events (AEs) in patients undergoing post-prostatectomy prostate bed radiotherapy.
- To evaluate the prognostic value of dose-volume histogram (DVH) parameters for predicting genitourinary (GU) and gastrointestinal (GI) toxicity.
- To determine if AEs occur even when commonly accepted dose constraints are met.
Main Methods:
- Retrospective analysis of 213 patients treated with post-prostatectomy prostate bed RT.
- Adverse events (AEs) were scored using the CTCAE v.5.0 criteria.
- Dose-volume histogram (DVH) parameters for the rectum and bladder were analyzed in relation to toxicity occurrence, including QUANTEC constraints.
Main Results:
- Acute grade 2 or higher (≥G2) GU AEs occurred in 18.7% and late in 21.3%; acute ≥G2 GI toxicity occurred in 11.7% and late in 11.2%.
- Rectal DVH parameters (V47, V46) were significant predictors of acute GI toxicity, while bladder DVH parameters predicted late GU toxicity.
- Significant AEs were observed even in patients adhering to standard dose constraints, indicating limitations in current predictive models.
Conclusions:
- Postoperative radiotherapy is linked to clinically relevant AEs predicted by DVH parameters, persisting even with adherence to dose constraints.
- Given the limited survival benefit of adjuvant RT, an early salvage approach is supported to minimize or postpone toxicity.
- Further research into refined DVH parameters and predictive models is warranted to optimize RT planning and reduce patient-related morbidity.
Keywords:
QUANTECadjuvant radiotherapyadverse eventsdose constraintsdose–volume histogrampostoperative irradiationprostate cancersalvage radiotherapy
