Tumour control probability after Ruthenium-106 brachytherapy for choroidal melanomas

Abstract

Purpose: Ruthenium-106 (Ru-106) brachytherapy is a common eye-preserving treatment for choroidal melanomas. However, a dose-response model describing the relationship between the actual delivered tumour dose and tumour control has, to the best of our knowledge, not previously been quantified for Ru-106 brachytherapy; we aimed to rectify this. Material and methods: We considered consecutive patients with primary choroidal melanomas, treated with Ru-106 brachytherapy (2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014). Dosimetric plans were retrospectively recreated using 3D image-guided planning software. Pre-treatment fundus photographies were used to contour the tumour; post-treatment photographies to determine the accurate plaque position. Patient and tumour characteristics, treatment details, dose volume histograms, and clinical outcomes were extracted. Median follow-up was 5.0 years. The relationship between tumour dose and risk of local recurrence was examined using multivariate Cox regression modelling, with minimum physical tumour dose (D 99% ) as primary dose metric. Results: We included 227 patients with median tumour height and largest base dimension of 4 mm (range 1-12, IQR 3-6) and 11 mm (range 4-23, IQR 9-13). The estimated 3 year local control was 82% (95% CI 77-88). Median D 99% was 105 Gy (range 6-783, IQR 65-138); this was the most significant factor associated with recurrence (p < .0001), although tumour height, combined TTT and Ru-106 brachytherapy, and sex were also significant. The hazard ratio (HR) for a 10 Gy increase in D 99% was 0.87 (95% CI 0.82-0.93). Using biological effective dose in the model resulted in no substantial difference in dose dependence estimates. Robustness cheques with D 1-99% showed D 99% to be the most significant dose metric for local recurrence. Conclusion:The minimum tumour dose correlated strongly with risk of tumour recurrence, with 100 Gy needed to ensure at least 84% local control at 3 years.

Predictive factors of radio‐induced complications in 194 eyes undergoing gamma knife radiosurgery for uveal melanoma

“…Although higher radiation dose has been associated with lower risk of tumour recurrence (Espensen, Appelt, et al. 2020), greater optic nerve damage should be expected (Gigliotti et al. 2018; Espensen, Kiilgaard, et al.…”

Predicting Visual Acuity Deterioration and Radiation-Induced Toxicities after Brachytherapy for Choroidal Melanomas

“…However, an optimal treatment strategy has to balance tumour control and the risk of healthy tissue toxicity, especially when a major treatment aim is to preserve normal function. We established a dose–response relationship for tumour control probability (TCP) after ruthenium-106 (Ru-106) brachytherapy in a previous work [3], but corresponding models for normal tissue complication probabilities (NTCP) are required in order to decide on treatment modality and optimise treatment at an individual patient level. We examined the relationship between radiation dose to healthy tissues and the risk of visual acuity deterioration and radiation-induced toxicity for a large cohort of patients with choroidal melanoma treated with Ru-106 brachytherapy.…”

3D image‐guided treatment planning for Ruthenium‐106 brachytherapy of choroidal melanomas

“…Prediction models for TCP and NTCP have previously been developed on a separate cohort (Espensen et al 2019; Espensen et al 2020) based on detailed evaluation of recurrence and specific late complications. Dose metrics identified as correlating with late outcomes in those papers were extracted from treatment plan DVHs/DSHs for the current study patient cases.…”

“…cervical cancer) has more recently been implemented into clinical practice (Sturdza et al 2016). Using previously developed prediction models (Espensen et al 2019; Espensen et al 2020), we evaluated the potential impact of 3D image‐guided treatment planning in terms of tumour control probability (TCP) and normal tissue complication probability (NTCP), compared to central axis‐based (2D) treatments.…”