Tumour Response in Uveal Melanomas Treated with Proton Beam Therapy

Abstract

AimsPost-proton therapy surveillance of uveal melanomas relies on decreased thickness on repeat ultrasound B every 6 months for 2 years and yearly thereafter. Earlier pseudoprogression, a phenomenon described in other tumour types within the first months of irradiation, can also be observed in uveal melanomas and may lead to inappropriate enucleation. The Collaborative Ocular Melanoma Study (COMS) has defined ultrasound criteria to identify tumour progression after brachytherapy. We aimed to determine the reliability of ultrasound as a means to measure tumour height after proton therapy and predict local relapse. Materials and methodsAll 1992–2012 consecutive patients with at least three ultrasound B measurements during follow-up were included. ResultsThere were 55 local relapses of 886 patients (6.2%). Ultrasound B reliability was highest at 24 months, with specificity higher than 95% starting at 18 months. ConclusionBefore 18 months post-proton therapy, the risk of falsely concluding in favour of a relapse exceeds 5% and should prompt repeat measurements 3 and 6 months later but should not prompt enucleation without further clinical assessment.