Proton radiotherapy in advanced malignant melanoma of the conjunctiva

Background The management of conjunctival melanoma is challenging and frequently ends in exenteration. The aim of this retrospective study was to evaluate the long-term results of proton beam radiation with regard to various clinical parameters. Methods Eighty-nine patients with extended conjunctival melanoma (≥T2) and multifocal bulbar located tumors (T1c/d) were treated consecutively with proton radiotherapy (dose 45 Gy). The following parameters were assessed: TNM stage, tumor origin, local recurrence, performance of exenteration, occurrence of metastases, overall survival, and potential complications. A time-to-event analysis was preformed to the primary endpoints: relapse, metastasis, exenteration, and death by use of Kaplan-Meier cumulative survival estimates and Cox proportional hazards regression that provides hazard ratios and 95% confidence intervals. Results The median follow-up time was 4.2 years (max. 21.7 years). Local recurrence and metastatic disease occurred in 33% and 16% of patients, respectively. Exenteration-free survival and overall survival tended to be worse in T3 melanoma. No association between tumor origin and local recurrence, metastatic disease, or overall survival was observed. Main complications after proton radiotherapy were sicca-syndrome (30%), secondary glaucoma (11%), and limbal stem cell deficiency (8%). Conclusions In summary, proton radiotherapy in conjunctival melanoma is an effective alternative to exenteration, with a 5-year cumulative probability of eye preservation of 69%.