Conservative treatment of uveal melanoma: Probability of eye retention after proton treatment

Enucleation was performed after proton treatment in 57 of 1006 (5.7%) uveal melanoma patients treated with proton beam therapy at the Harvard Cyclotron Laboratory between July 1975 and December 31, 1986. Only 2% of 99 patients with small tumors and 4% of 566 patients with intermediate size tumors underwent enucleation after treatment; 10% of 341 patients with large tumors lost the treated eye. No eyes were removed after 52 months, with 89% of enucleations performed during the first 36 months after treatment. Eye retention rates at 60 months were 89.1 ± 3.0% for the entire group, and 97 ± 3.7%, 92.7 ± 3.1%, and 78.3 ± 7.0% in patients with small, intermediate, and large tumors, respectively. Significantly greater enucleation rates were observed in patients with large tumors than in those with intermediate tumors (p = <.0001), in patients with tumor height > 8 mm relative to those with tumors ≤ 8 mm, p = (<.0001), with tumor diameter > 16 mm compared to ≤16 mm, (p = <.0001), and with tumor involvement of the ciliary body compared to involvement of the choroid only (p = <.0001). Possible strategies to decrease the likelihood of enucleation in patients at apparently increased risk of losing the eye after conservative therapy, that is, those with large tumors involving the ciliary body, might include a lower total dose, a more protracted treatment course, or a lower radiation dose and adjuvant treatment with chemotherapy and/or immunotherapy, with hyperthermia, or with other radiation sensitizers.