Iodine Brachytherapy versus Transpupillary Thermotherapy for Choroidal Melanoma: Long–term Choroidal Vascular Changes.

Abstract

Abstract: : Purpose:To compare long–term choroidal vascular alterations observed in small or medium choroidal melanoma after iodine– 125 brachytherapy versus those observed after transpupillary thermotherapy. Methods: Sixty–nine eyes of 69 patients affected by malignant choroidal melanoma with a largest basal tumor diameter smaller than 10 mm and tumor height smaller than 3.5 mm were treated with either transpupillary thermotherapy (TTT) (35 eyes) or iodine–125 brachytherapy (34 eyes) (IBT). Fluorescein and indocyanine green (ICG) angiography were performed at 3–month intervals during the first year, and every 6 months thereafter. Results: The mean follow–up was 35.5 months (range 24– 58 months). Long–term changes of choroidal circulation were limited to the treated area after TTT, while they involved larger areas of the choroid beyond the treatment margins after IBT. Occlusion of choriocapillaris was observed in all cases (100%). Closure of medium and large choroidal vessels progressively also occurred in 98% of the cases treated with IBT versus 34% of the eyes treated with TTT (p < 0.05). The patency of these choroidal vessels was associated with retinochoroidal anastomosis in four cases treated with TTT (11%), never detected after IBT. In both the TTT and the IBT groups we observed a choroidal vascular remodelling (in 42% and in 35% respectively). In the eyes treated with IBT choroidal vascular remodelling was characterized by the presence of segments of choroidal vasculitis, choroidal aneurysmal changes and ICG leakage in the late phases of the angiogram. Retinochoroidal anastomosis was observed in all cases of local failure of TTT (four cases). Conclusions: Radiotherapy induces slow, progressive and complete occlusion of choroidal vasculature; the same does not apply in most cases of the TTT treated eyes. The persistent patency of choroidal circulation, choroidal vascular remodelling and retinochoroidal anastomosis seem to be important predictive factors of recurrence after TTT. The high rate of choroidal vascular closure after IBT as compared with TTT may perhaps mean a better local control of the tumor. Therefore ICG angiography is important for the follow–up of patients who received forms of treatment (TTT or IBT) of which long–term safety and efficacy are still under investigation.

Keywords: melanoma • radiation therapy • choroid