Adjuvant radiotherapy in orbital malignancy

1 June 2022 | James Hsuan | EYE - Oculoplastic, EYE - Orbit

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This is a retrospective review of high dose volumetric modulated arc radiotherapy (VMAT) for adjuvant treatment of patients with orbital malignancy who had already undergone local excision or exenteration. VMAT differs from conventional external beam radiotherapy in that it is a form of intensity modulated treatment where portions of the beam are blocked, and delivered in an arc or series of arcs rather than in a square or rectangular shaped beam. This allows better focusing of the beam on the target areas whilst minimising exposure to other critical structures. Eighty-four patients comprising 48 local excisions and 36 exenterations underwent VMAT with a mean dose of 65Gy. After a mean follow-up of 18 months, there was no change in visual acuity in the local excision group, and only single cases each of bacterial keratitis, corneal opacification, radiation retinopathy, radiation optic neuropathy and cicatricial entropion. Severe dry eye occurred in three patients. The incidence of these complications was far lower than that reported with conventional external beam radiotherapy. The study suggests this is a treatment with fewer serious side-effects, but the follow-up may be too short for some later complications and there was no data on tumour recurrence rates.