Impact of tumour volume and treatment delay on the outcome after linear accelerator-based fractionated stereotactic radiosurgery of uveal melanoma

Abstract

Background/aimsPrimary radiation therapy is used to treat malignant uveal melanoma (UM). We report our single-centre experience with fractionated radiosurgery (fSRS) with a linear accelerator (LINAC) after specific adaptation for small target volumes with HybridArc.MethodsFrom October 2014 to January 2020, 101 patients referred to Dessau City Hospital with unilateral UM underwent fSRS with 50 Gy given in five fractions on five consecutive days. Primary endpoints were local tumour control, globe preservation, metastasis and death. Potential prognostic features were analysed. Kaplan-Meier analysis, Cox proportional hazards model and linear models were used for calculations.ResultsThe median baseline tumour diameter was 10.0 mm (range, 3.0–20.0 mm), median tumour thickness 5.0 mm (range, 0.9–15.5 mm) and median gross tumour volume (GTV) 0.4 cm³ (range, 0.2–2.6 cm³). After a median follow-up of 32.0 months (range, 2.5–76.0 months), 7 patients (6.9%) underwent enucleation: 4 (4.0%) due to local recurrence and 3 (3.0%) due to radiation toxicities, and 6 patients (5.9%) revealed tumour persistence with a GTV exceeding 1.0 cm³. Of 20 patients (19.8%) who died, 8 (7.9%) were tumour-related deaths. Twelve patients (11.9%) suffered from distant metastasis. GTV showed an impact on all endpoints, and treatment delay was associated with reduced odds of eye preservation.ConclusionLINAC-based fSRS with static conformal beams combined with dynamic conformal arcs and discrete intensity-modulated radiotherapy results in a high tumour control rate. The tumour volume is the most robust physical prognostic marker for local control and disease progression. Avoiding treatment delay improves outcomes.

Impact of Choroidal Melanoma Characteristics on Progression-Free Survival in Patients Undergoing Hypofractionated Stereotactic Photon Radiotherapy

“…The percentage of eyes that were enucleated in this patient collective after they had received LINAC therapy was 16.6% (58) during a follow-up period of up to 15 years (6 months to 15 years), and enucleation was most commonly due to neovascular glaucoma, which is in line with the literature (6.9–14.7%) [ 31 – 34 ]. Sixteen (4.6%) of these patients underwent enucleation due to tumor progression.…”

“…The median time until progression after LINAC treatment was 13.5 (range 7–18) months. The corresponding time in a previous study was 17.9 (range 10.9–43.6) months [ 31 ]. This shows that the most vulnerable phase concerning progression after treatment may be between 1 and 2 years after LINAC therapy, which further supports omitting thickness measurements, especially in the long-term post-treatment monitoring phase.…”

“…As ultrasonography is not ubiquitously available in many health care systems or facilities, patients with choroidal nevi or melanoma have to be monitored and followed up in sparse centers of expertise, so the question arises as to whether measurements using ultrasonography, in particular thickness measurements, may be replaced by measurements of other parameters such as LBD or tumor base area to detect change, as these parameters may be extracted from, e.g., fundus photography. We have also included volume (although thickness measurements are necessary for volume calculations), as it was previously shown that gross tumor volume, thickness, LBD, and time till therapy are prognostic for local recurrence-free survival [ 31 ]. With respect to tele-medicine and virtual surveillance of patients living far from oncology centers, we focused the research question solely on patient follow-up following treatment for choroidal melanoma, excluding the process of diagnosis and therapy finding as well as choroidal nevi from this research approach.…”

Ruthenium-106 Brachytherapy and Central Uveal Melanoma

“…This can be promptly controlled through direct binocular fundoscopy while placing the plaque. Concerning all treatment options an early detection of the UM and fast treatment is necessary for effective therapy because the size of the UM has an impact of the treatment success [3,24].…”

“…Brachytherapy is preferentially used for peripheral UM with an apical height up to 6 mm or central UM close to the fovea with an apical height up to 6 mm. We use stereotactic radiotherapy with photons successfully for UM with an apical height more than 6mm and UM close to or abutting the optic disc and achieved high local control rates [24]. Regarding the personal situation of each patient such as high age, underlying diseases and immobilization different treatment options for a personalized therapy such as Ru-106 Brachytherapy with adjuvant transpupillary thermotherapy is also a treatment possibility.…”