Adjuvant brachytherapy with strontium-90 or ruthenium-106 in conjunctival melanoma

Abstract

Purpose : Limited data are available on the outcome of different brachytherapy modalities in conjunctival melanoma, as the disease is rare and data is often pooled for statistical purposes. This study evaluates and compares the clinical outcome of adjuvant brachytherapy with either Strontium-90 or Ruthenium-106 in conjunctival melanoma.

Methods : A retrospective review was performed of the clinical data of 58 patients who received adjuvant brachytherapy after local resection of conjunctival melanoma with either a Sr-90 handheld-applicator or a Ru-106 plaque in the Leiden University Medical Center (the Netherlands) between 1999 and 2016. The protocol with adjuvant Sr-90 was used in our institution until 2012, the protocol with adjuvant Ru-106 was used hereafter for logistical reasons. Local recurrence, metastasis, survival, visual acuity and treatment complications were assessed.

Results : A total of 32 patients were treated with adjuvant Sr-90 and 26 with adjuvant Ru-106. All lesions were epibulbar, with a mean thickness of 1.12 mm and a mean largest basal diameter of 6.82 mm. Mean age at diagnosis was 58.9 years. There were no differences in baseline tumour characteristics between the two groups. Mean follow-up of patients treated with Sr-90 was 113.4 months, and 29.0 months for patients treated with Ru-106. Local recurrence occurred in 8 cases (25%) after Sr-90, and 5 cases (19%) after Ru-106 (p=0.60), with 3- and 5-year recurrence rates of 16% and 19%, versus 32% and 32%, respectively (p=0.45). Metastasis developed in 2 cases (6%) after Sr-90, and 1 patient (4%) after Ru-106 (p=1.00), with 3- and 5-year metastasis rates of 3% and 7%, versus 4% and 4%, respectively (p=0.83). Melanoma-related death was seen in 3 patients (9%) after Sr-90 treatment, and in none after Ru=106 treatment (p=0.25). Most reported overall complications were pain or discomfort (29%), dry eye symptoms (21%), symblepharon (9%), ptosis (12%) and cataract (7%). No severe corneal or scleral problems were observed. Median visual acuity was 20/20 pre-surgery as well as at the end of follow-up, in both treatment groups.

Conclusions : Adjuvant brachytherapy with Sr-90 or Ru-106 provides good tumour control with few side effects in patients with limited conjunctival melanoma. No statistically significant differences in treatment outcome were detected. The choice for either treatment may be based on experience of the clinician and availability of materials.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.