Feasibility of partial-orbit irradiation as a treatment strategy for patients with orbital mucosa-associated lymphoid tissue lymphoma.

OBJECTIVE:For early-stage orbital mucosa-associated lymphoid tissue lymphoma (MALToma), radiotherapy (RT) is known to be the treatment of choice. The classical recommended treatment field is the entire ipsilateral orbit, exposing normal orbital structures such as the lacrimal gland and lens, which are sensitive to moderate doses of radiation, to the full treatment dose. Herein we aimed to evaluate the clinical outcomes and dosimetric values in patients with orbital MALToma who received RT. DESIGN:This study was a retrospective study. PARTICIPANTS:Forty patients with orbital MALToma treated with curative RT. METHODS:The patients were classified into the conjunctival RT (n = 23), partial-orbit RT (n = 10), and whole-orbit RT (n = 7) groups. The treatment outcomes and dosimetric values of the orbital structures were reviewed. RESULTS:We found the 5-year local, contralateral orbit, and overall relapse rates to be 5.0%, 5.9%, and 16.0%, respectively. Local relapse events occurred in 2 patients in the conjunctival RT group. No relapse was observed in the partial-orbit RT group. Whole-orbit RT caused significantly higher rates of dry eyes during treatment. The partial-orbit RT group showed a significantly lower ipsilateral eyeball mean dose and ipsilateral eyelid mean dose than the other groups. CONCLUSION:Partial-orbit RT showed encouraging clinical, toxicity, and dosimetric outcomes in patients with orbital MALToma and has the potential to be a treatment option for such patients.