Visual acuity, oncologic, and toxicity outcomes with 103Pd vs. 125I plaque treatment for choroidal melanoma

Abstract

Purpose: To evaluate outcomes of choroidal melanoma patients treated with ¹²⁵I or ¹⁰³Pd plaque brachytherapy.

Methods and materials: From 1993 to 2012, our institution treated 160 patients with ¹⁰³Pd (56.1%) and 125 patients with ¹²⁵I (43.9%) plaque brachytherapy. Tumor outcomes, visual acuity (VA), and toxicity were compared. Multivariate analyses (MVAs) and propensity score analysis were used to help address differences in baseline characteristics.

Results: Median followup was longer for ¹²⁵I patients, 52.7 vs. 43.5 months (p < 0.01). At baseline, ¹⁰³Pd patients had lower rates of VA worse than 20/200 (4.4% vs. 16%, p = 0.002), T3-T4 tumors (17.5% vs. 32.8%, p = 0.03), and transpupillary thermotherapy use (3.1% vs. 9.6%, p = 0.001). Both ¹⁰³Pd and ¹²⁵I provided >90% 3-year overall survival and >93% 5-year secondary enucleation-free survival. On MVA, radionuclide was not predictive for tumor outcomes. A higher percentage maintained vision better than 20/40 with ¹⁰³Pd (63% vs. 35%, p = 0.007) at 3 years. MVA demonstrated ¹⁰³Pd radionuclide (odds ratio [OR]: 2.12, p = 0.028) and tumor height ≤5 mm (OR: 2.78, p = 0.017) were associated with VA better than 20/40. Propensity score analysis matched 23 ¹²⁵I with 107 ¹⁰³Pd patients. ¹⁰³Pd continued to predict better VA at 3 years (OR: 8.10, p = 0.014). On MVA for the development of VA worse than 20/200 or degree of vision loss, radionuclide was not significant. Lower rates of radiation retinopathy were seen with ¹⁰³Pd than ¹²⁵I (3 years: 47.3% vs. 63.9%, p = 0.016), with radionuclide significant in MVA.

Conclusions: Both ¹²⁵I and ¹⁰³Pd achieve excellent tumor control. An increased probability of long-term VA better than 20/40 and reduced risk of radiation retinopathy is associated with ¹⁰³Pd.

Keywords: Choroidal melanoma; Episcleral plaque brachytherapy; Iodine; Palladium.