Radiotherapy for adenoid cystic carcinoma of the lacrimal gland: Study on twelve patients

Abstract

Purpose: Despite its slow growth pattern, adenoid cystic carcinoma of the lacrimal gland poses challenges due to its high recurrence rate. The rarity of this entity hinders the establishment of prospective studies and a consensus on optimal treatment strategies. Herein, we aim to report the results of patients with adenoid cystic carcinoma of the lacrimal gland treated with hypofractionated stereotactic body radiations or conventionally-fractionated radiations.

Materials and methods: This study included patients with non-metastatic adenoid cystic carcinoma of the lacrimal gland treated with a curative-intent from 2006 to 2019. Patient data, tumour characteristics, treatment details, and follow-up information were collected. Recurrence patterns, oncologic outcomes, and toxicity were assessed.

Results: We evaluated the data of 12 patients with a median 29years of age who received stereotactic body radiotherapy (n=5) or conventionally-fractionated radiotherapy (n=7). After a median follow-up of 98months, the overall local control rate was 50 %, with recurrences mostly marginal to the radiotherapy field. Although the 10-year overall survival rate was a promising 92 %, the respective rate for local recurrence-free survival was 37 %, which was significantly lower in patients who received stereotactic body radiotherapy (20 %) compared to patients who had with conventionally-fractionated radiotherapy (72 %). Although not statistically significant, patients in the stereotactic body radiotherapy arm encountered a higher rate of severe late toxicity (80 % versus 17 % in the conventionally-fractionated radiotherapy arm, P=0.07). The overall eye preservation rate was 64 %, all eye-losses due to local recurrence.

Conclusion: Our findings raise concerns about using stereotactic body radiotherapy for adenoid cystic carcinoma of the lacrimal gland based on increased rates of severe late toxicity and local recurrence. Conventional radiotherapy techniques should be applied to these patients to successfully control the local tumour with less toxicity.

Keywords: Adenoid cystic carcinoma; Adjuvant radiotherapy; Carcinome adénoïde kystique; Glande lacrymale; Lacrimal gland; Radiothérapie adjuvante; Radiothérapie stéréotaxique corporelle; Stereotactic body radiotherapy; Toxicity; Toxicité.