Abstract
Purpose :
Uveal melanoma (UM), the most common primary ocular malignancy in adults, can arise from the malignant transformation of a choroidal nevus. The Cancer Genome Atlas (TCGA), a recently described classification system based on cytogenetic aberrations on chromosomes 3 and 8, provides a reliable prognostication of metastasis and death in UM. We hypothesize that high-grade tumors (TCGA C or D), which portend higher rates of metastasis and death, arise from a nevus with greater rate of growth and faster time to transformation compared to a low-grade tumor (TCGA A or B).
Methods :
A retrospective review was conducted for patients diagnosed with choroidal nevus demonstrating transformation into UM. There were 86 patients who underwent fine-needle aspiration and cytogenetic analysis of the tumor. Clinical risk factors for transformation, such as visual symptoms, tumor base size, tumor thickness, echogenicity on ultrasound, and presence of orange pigment or subretinal fluid at date of nevus diagnosis and date of transformation (DOT) to UM were recorded. Student’s t-test was used for continuous variables and chi-squared test was used for categorical variables.
Results :
Of the 86 patients with transformation of choroidal nevus into melanoma, 66% (57/86) were cytogenetically low-grade and 34% (29/86) were cytogenetically high-grade. Fast transformation of choroidal nevi (≤ 1 year) into UM was seen in 21% (18/86) of patients and slow transformation (> 1 year) was seen in 79% (68/86) of patients. Tumors with fast transformation showed similar rates of low-grade and high-grade cytogenetics (56% vs. 44%, p=0.64), however slow transformation tumors showed a greater predilection of low-grade cytogenetics (69% vs. 31%, p=0.002). When comparing high-grade tumors to low-grade tumors, the former showed greater rate of base size increase (2.3 vs. 0.7 mm/year, p=0.03), greater rate of thickness increase (1.1 vs. 0.5 mm/year, p=0.04), and greater presence of clinical risk factors at DOT (5.0 vs. 4.0, p>0.001).
Conclusions :
Choroidal nevus with documented fast transformation (≤ 1 year) can possess a high or low-grade cytogenetic profile, however a nevus that slowly transforms (> 1 year) will more likely demonstrate low-grade cytogenetics, predictive of lower rates of metastasis and death. Faster rates of increase in base size and thickness predicted high-grade cytogenetics, suggestive of higher rates of metastasis and death.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.