Proton beam radiation for iris melanoma: case series and review of literature

OBJECTIVE: Purpose of this study is to analyse the visual outcomes, the complication and eye retention rate as well as tumour control data of patients treated with proton beam radiation therapy (PBRT) for iris melanoma. METHODS: Retrospective case series and review based on patients’ records. All tumours were categorised according to the American Joint Committee of Cancer staging criteria for primary iris melanoma und underwent either sectorial or whole anterior segment PBRT. RESULTS: Thirteen cases were identified of which five received PBRT of the whole anterior segment and eight received sectorial PBRT. Local tumour control after a mean follow-up of 25 months was 92%. Complications after PBRT included cataract (46%), secondary glaucoma (31%), superficial keratitis (15%) and madarosis (8%). Complications were more common in patients necessitating irradiation of the entire anterior segment than in patients which received sectorial irradiation. Eye retention was achieved in all cases. No statistically significant difference in the mean best corrected visual acuity (BCVA) and intraocular pressure (IOP) was found before and after treatment. Comparison of mean BCVA and IOP between different treatment groups (complete anterior segment vs sectorial irradiation) at the last follow-up visit were also not significantly different. No patient developed metastatic disease during follow-up. CONCLUSION: PBRT is a safe and vision preserving therapeutic modality for iris melanoma. Complete irradiation of the anterior segment is associated with higher complication rates.