Accessory secondary plaque in brachytherapy for uveal melanoma

We describe the technique, indications and outcomes of an accessory secondary brachytherapy plaque for the treatment of uveal melanoma to provide supplemental tumor coverage for the primary brachytherapy plaque.

Retrospective case series was performed to identify brachytherapy plaque cases for the treatment of primary uveal melanoma where an accessory secondary plaque was created to improve treatment coverage of the uveal melanoma, and positioned at the time of removal of the primary brachytherapy plaque. Baseline tumor, patient characteristics, and clinical outcomes including tumor control, visual acuity, treatment complications, metastases and death treatment were obtained.

Of 1,144 uveal melanomas treated with brachytherapy over a 19-year period, eight (0.7%) cases were identified where an accessory secondary brachytherapy plaque was used. Six (75%) patients had uveal melanoma involving the ciliary body. After a mean follow up period of 31.5 ± 5.65 (SE) months, seven (87.5%) patients maintained tumor control and the mean visual acuity was logMAR 0.84 ± 0.57 (Snellen equivalent 20/138). Two (25%) patients developed metastasis, and one (12.5%) patient died of metastatic disease.

An accessory brachytherapy plaque is a practical solution to manage unexpected deficiencies in plaque coverage of the primary melanoma which avoids treatment delay and minimizes time for potential tumor growth. It may also avoid suboptimal adjunctive treatment options, such as transpupillary thermotherapy, and eliminates radioactive source loss if an entirely new brachytherapy plaque was created. A well-matched accessory secondary plaque may also better conform to the target than a generic plaque with a larger diameter.