Dose-volume analysis of planned versus accumulated dose as a predictor for late gastrointestinal toxicity in men receiving radiotherapy for high-risk prostate cancer. (July 2022)

• Record Type: Journal Article
• Authors: Ong, Ashley L.K; Knight, Kellie; Panettieri, Vanessa; Dimmock, Mathew; Tuan, Jeffrey K.L; Tan, Hong Qi; Wright, Caroline
• Is Part Of: Physics and imaging in radiation oncology. Volume 23(2022)
• Page Start: 97
• Page End: 102
• Publication Date: 2022-07
• Subjects: Accumulated dose -- Predictive model -- Gastrointestinal toxicity -- High-risk prostate -- Volumetric image-guidance; Radiotherapy -- Periodicals; Radiation dosimetry -- Periodicals; Cancer -- Imaging -- Periodicals; Oncology -- Periodicals; 615.842
• DOI: 10.1016/j.phro.2022.07.001
• Languages: English
• ISSNs: 2405-6316

Abstract

Highlights: Interfractional variations in organs at risk were observed in prostate radiotherapy. Rectal accumulated dose was significantly higher at the intermediate-high dose region. Rectal planned dose was significantly higher at the very high dose region. Dose>78.2 Gy to 0.03 cc of rectum was predictive of late Grade 2 toxicity. Patient age>72 years was predictive of late Grade 2 rectal toxicity. Abstract: Background and purpose: Significant dose deviations have been reported between planned (DP ) and accumulated (DA ) dose in prostate radiotherapy. This study aimed to develop multivariate analysis (MVA) models associating Grade 1 and 2 gastrointestinal (GI) toxicity with clinical and DP or DA dosimetric variables separately. Materials and methods: Dose volume (DV) metrics were compared between DA and DP for 150 high-risk prostate cancer patients. MV models were generated from significant clinical and dosimetric variables (p < 0.05) at univariate level. Dose-based-region of interest (DB-ROI) metrics were included. Model performance was measured, and additional subgroup analysis were performed. Results: Rectal DA demonstrated a higher intermediate-high dose (V30-65 Gy and DB-ROI at 15–50 mm) compared to DP . Conversely, at the very high dose region, rectal DA (V75 Gy and DB-ROI at 5–10 mm) were significantly lower. In MVA, rectal DB-ROI at 10 mm was predictive for Grade ≥ 1 GI toxicity for DA and DP . Age, rectal DA for D0.03 cc, and rectal DP for DB-ROI 10 mm were predictors for Grade 2 GI toxicity. Subgroup analysis revealed that patients ≥ 72 years old and a rectal DA of ≥ 78.2 Gy were highly predictive of Grade 2 GI toxicity. Conclusions: The dosimetric impact of a higher dose rectal dose in DA due to volumetric changes was minimal and was not predictive of detrimental clinical toxicity apart from rectal D0.03 cc ≥ 78.2 Gy for Grade 2 GI toxicity. The use of the DB-ROI method can provide equivalent predictive power as the DV method in toxicity prediction.