Radiotherapy Dose and Volume De-escalation in Ocular Adnexal Lymphoma

Modern radiotherapy (RT) technique and therapy de-escalation have led to encouraging results in lymphoma management. In this study, we aimed to describe the oncological and toxicity outcome in patients with ocular adnexal lymphoma.

A total of 45 patients with 52 orbital lesions who were treated at our Institution between 2003 and 2019 were considered. Clinical characteristics, treatment outcomes, and toxicity were assessed. Patients receiving 4-6 Gy were categorized as receiving ultra-low-dose RT, 24-30.6 Gy as standard-dose RT, and >30.6 Gy as high-dose RT.

The predominant histological subtype was marginal zone lymphoma in 39 lesions (75%). Radiation dose ranged from 4-50.4 Gy. In the whole cohort, 11% of the lesions were treated with ultra-low-dose RT, 33% with standard-dose RT, and 56% with high-dose RT; 60% of lesions were treated using intensity-modulated RT (IMRT), while 44% of lesions were treated with partial orbital RT. The median duration of follow-up was 33 months. The overall response rate was 94% (complete response rate=83%). The 5-year local control rate, progression-free survival, and overall survival were 100%, 76%, and 92%, respectively. We did not detect any significant difference in progression-free or overall survival regarding different radiation doses and volumes. Ultra-low-dose RT was associated with a significantly lower rate of grade 2 late toxicities (0% vs. 6% and 31%, p=0.05) in comparison with standard-dose and high-dose RT, respectively. Patients who received IMRT had a significant fewer acute grade 2 (16% vs. 43%, p=0.05) and a trend towards lower late grade 2 toxicities (9% vs. 33%, p=0.06).

Radiation dose and volume de-escalation seem to be safe and effective, with excellent local control and survival in the management of ocular adnexal lymphoma. IMRT seems to be associated with less toxicity.