Brachytherapy of Choroidal Melanomas Less Than 10 mm in Largest Basal Diameter
Susanna Jouhi,Jorma Heikkonen,Vappu Reijonen,Virpi Raivio,Martin Täll,Tero T. KiveläRead More
To compare tumor control, vision, and complications between patients with a choroidal melanoma of <10 mm in largest basal diameter (LBD) irradiated with 10-mm or 15-mm ruthenium plaques.
Retrospective, comparative case series.
One hundred sixty-four consecutive patients with a choroidal melanoma of <10 mm in LBD, 76 and 88 treated with the 10-mm and 15-mm plaque, respectively, from 1998–2014 in a national ocular oncology service.
Diagnosis was based on growth or high-risk characteristics. The apical dose was 100 to 120 Gy aiming to deliver ≥250 Gy to the sclera. Plaque positioning was modeled retrospectively. An increase of ≥0.3 mm in thickness and ≥0.5 mm in LBD indicated local recurrence. Outcomes were compared with cumulative incidence analysis and Cox regression. Median follow-up time for patients still alive was 8.4 years.
Main Outcome Measures
Recurrence rate, low vision, blindness, radiation maculopathy, and optic neuropathy.
Melanomas treated with the 10-mm plaque were smaller (median thickness, 1.9 mm vs. 2.6 mm; LBD, 7.1 mm vs. 8.6 mm) and located closer to foveola (median, 2.0 mm vs. 2.8 mm) than those treated with the 15-mm plaque (P < 0.001). The 2 plaques provided a safety margin in 43% versus 40% eyes, provided no safety margin to guard foveola in 17% versus 33%, and did not entirely cover tumor mainly close to the disc in 32% versus 18% of eyes, respectively (P = 0.052). The incidence of a local recurrence was comparable (13% vs. 15% at 10 years; P = 0.31) and associated with plaque positioning (hazard ratio [HR], 2.81 for no safety margin; P = 0.041). At 5 years, the incidence of low vision was 14% versus 24%, and that of blindness was 3% versus 6%. Distance to the foveola was associated with loss of both levels of vision (HR, 0.65 per 1 mm vs. 0.68 per 1 mm; P ≤ 0.001 vs. P = 0.004). The incidence of radiation maculopathy was comparable (19% vs. 18% at 5 years), whereas that of optic neuropathy tended to be higher with the 15-mm plaque (2% vs. 9%; P = 0.054).
The 10-mm ruthenium plaque contributes to better visual preservation, particularly with tumors close to fovea, without increase in local recurrence rate, and may therefore be preferable to the 15-mm plaque.