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

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

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.

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.

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.