Высокие дозы облучения диска зрительного нерва и желтого пятна повышают риск потери зрения при лечении меланомы

Among patients with posterior uveal melanoma (PUM) treated with plaque radiotherapy, higher radiation doses to the optic disc and foveola are associated with greater long-term risk of ≥15-letter visual acuity loss, according to results of a study published in Retina. Researchers conducted a retrospective study of 4000 eyes with PUM involving the choroid and/or ciliary body that were treated with a single course of plaque radiotherapy at Wills Eye Hospital between 1976 and 2008, without prophylactic anti–vascular endothelial growth factor (anti-VEGF) injections or laser photocoagulation. Tumors were categorized by thickness as small (0-3.0 mm), medium (3.1-8.0 mm), or large (>8.0 mm). Radiation exposure was stratified by optic disc dose (≤4000 vs >4000 cGy) and foveolar dose in 1000- or 2000-cGy increments. The primary outcome was a 15-letter or more visual acuity loss. Of the 4000 eyes, 1011 (25%) had small, 2445 (61%) medium, and 544 (14%) large tumors. Median patient age was 60 years, median tumor thickness was 4.5 mm, and median radiation doses were 8079 cGy to the tumor apex, 3346 cGy to the optic disc, and 4021 cGy to the foveola. Over a median follow-up of 45 months, cumulative ≥15-letter visual acuity loss increased from 30% at 1 year to 48% at 2 years, 60% at 3 years, 73% at 5 years, 82% at 10 years, and 90% at 20 years. With optic disc dose ≤4000 cGy and foveal dose 0-2000 cGy, visual preservation was achieved in nearly 50% at 20 years. Higher doses to these structures led to worse visual outcomes. Vision loss increased with greater radiation exposure to both the optic disc and foveola. Among eyes receiving ≤4000 cGy to the optic disc, ≥15-letter loss occurred in 38% of eyes with a foveolar dose of 0-1000 cGy, 52% with 1001-2000 cGy, 59% with 2001-3000 cGy, 68% with 3001-4000 cGy, and 71% with 4001-5000 cGy. For eyes receiving ≤4000 cGy to the optic disc, increasing foveolar dose was associated with progressively poorer visual acuity survival. Compared with a foveolar dose of less than 2000 cGy, a dose of 2001-4000 cGy was associated with a 71% higher hazard of 15-letter or more loss (HR, 1.71; 95% CI, 1.47-1.99; P <.01). Increasing the dose from 2001-4000 to 4001-6000 cGy was associated with a further increase in risk (HR, 1.21; 95% CI, 1.01-1.45; P =.03). Among eyes receiving greater than 4000 cGy to the optic disc, visual acuity survival was uniformly poor across foveolar dose categories. Notably, with an optic disc dose of 4000 cGy or lower and foveolar dose of 2000 cGy or lower, nearly 50% of eyes maintained visual preservation at 20 years, suggesting that minimizing radiation exposure to these visually critical structures may improve long-term outcomes. Study limitations include the retrospective design; the approximately 4-decade study period during which radiation physics and computer simulation techniques evolved; and potential variability in radioactive seed placement, plaque orientation/design, and surgical placement, which could have influenced the estimated radiation exposure to ocular structures. “With optic disc dose ≤4000 cGy and foveal dose 0-2000 cGy, visual preservation was achieved in nearly 50% at 20 years. Higher doses to these structures led to worse visual outcomes,” explain the researchers. “As this is one of the modifiable factors in our care of patients with PUM, consideration for lowering doses to these visual structures, perhaps with neoadjuvant tumor shrinkage, could benefit patient visual outcomes.” This article originally appeared on Ophthalmology Advisor