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To evaluate the safety and efficacy of stereotactic radiosurgery as an alternative to exenteration surgery in patients with orbital invasion by squamous cell carcinoma (SCC) of the conjunctiva.

Patients who had stereotactic radiosurgery for biopsy-proven conjunctival SCC invading the orbit but sparing the bone with a minimum of 1 year follow up were included. Treatment failure was defined as no decrease in tumour size 3 months after treatment. Patients were followed up 3-monthly for 2 years and 6-monthly afterwards with a minimum of yearly MRI scan of orbit.

Five patients met the inclusion criteria. The median age at presentation was 67 years. In all patients the SCC involved the bulbar and the forniceal conjunctiva. In two patients the caruncle was involved. An MRI confirmed extension of the SCC into the orbit and involvement of at least one rectus muscle. Stereotactic radiosurgery was done in a single session during which each patient received a marginal dose of 20 Gy. The mean follow-up was 30.2 months. Four patients responded to the treatment and had no evidence of recurrence by their last available follow-up visit. The patient whose tumour did not respond had the most aggressive disease as the tumour had indistinct margins on MRI orbits. He needed exenteration surgery with radical neck dissection three months later but eventually passed away from brain invasion.

Stereotactic radiosurgery should be considered as an alternative to exenteration surgery in the treatment of conjunctival SCC invading the orbit. It carries less morbidity and allows patients to maintain their vision. However, it is less likely to be successful when the SCC involves an extensive orbital area.