Dosimetry and Gastrointestinal Toxicity Relationships in a Phase II Trial of Pelvic Lymph Node Radiotherapy in Advanced Localised Prostate Cancer.
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ICR Authors
Authors
Ferreira, MR
Thomas, K
Truelove, L
Khan, A
Parker, C
Dearnaley, DP
Gulliford, S
Thomas, K
Truelove, L
Khan, A
Parker, C
Dearnaley, DP
Gulliford, S
Document Type
Journal Article
Date
2019-06-01
Date Accepted
2019-02-04
Date Available
Abstract
AIMS: Pelvic lymph node (PLN) radiotherapy for high-risk prostate cancer is limited by late gastrointestinal toxicity. Application of rectal and bowel constraints may reduce risks of side-effects. We evaluated associations between intensity-modulated radiotherapy (IMRT) dose-volume data and long-term gastrointestinal toxicity. MATERIALS AND METHODS: Data from a single-centre dose-escalation trial of PLN-IMRT were analysed, including conventionally fractionated (CFRT) and hypofractionated (HFRT) radiotherapy schedules. Associations between volumes of rectum and bowel receiving specified doses and clinician- and patient-reported toxicity outcomes were investigated independently. A metric, δ median (δM), was defined as the difference in the medians of a volume between groups with and without toxicity at a specified dose and was used to test for statistically significant differences. RESULTS: Constraints were respected in most patients and, when exceeded, led to higher rates of gastrointestinal toxicity. Biologically relevant associations between rectum dose-points and toxicity were more numerous with both mild and moderate toxicity thresholds, but statistical significance was limited after correction for false discovery rate. Rectal V50Gy (CFRT) associated with grade 2+ bleeding; bowel V43Gy and V47 (HFRT/4 days/week schedule) associated with patient-reported loose stools and diarrhoea, respectively. Further investigation showed that CFRT patients with rectal bleeding had a mean rectal V50Gy above the treatment planning constraint. CONCLUSIONS: When dose-volume parameters are kept below tight constraints, toxicity is low. Residual dosimetry loses much of its predictive power for gastrointestinal toxicity in the setting of PLN-IMRT for prostate cancer. We have benchmarked dose-volume constraints for safely delivering PLN-IMRT using CFRT or HFRT.
Citation
Clinical oncology (Royal College of Radiologists (Great Britain)), 2019, 31 (6), pp. 374 - 384
Source Title
Publisher
ELSEVIER SCIENCE LONDON
ISSN
0936-6555
eISSN
1433-2981
Research Team
Clinical Academic Radiotherapy (Dearnaley)
Radiotherapy Physics Modelling
Radiotherapy Physics Modelling