Uveal melanoma develops earlier in Asians
Uveal melanoma (UM) presents at a younger age for Chinese and Asian-Indian patients than it does for Caucasians, according to a new Singapore study.
“For this uncommon tumour, an approach using a regional registry replete with information on the gene expression profile will be invaluable in understanding the disease spectrum in the Southeast Asian population, and will also enable individualized treatment to improve long-term survival,” said researchers.
In a retrospective case analysis of 11 consecutive UM patients (median age at presentation, 42.9 years; 54.5 percent female), the most common presenting symptom was blurring of vision, reported by 81.8 percent (n=9). The most common initial diagnosis was melanoma (36.4 percent; n=4), and majority of the patients received their definitive diagnoses 1–6 months after initial presentation. [Singapore Med J 2019;doi:10.11622/smedj.2019054]
“Notably, all patients with UM in our series had [choroidal melanoma],” researchers pointed out.
After delivery of the final diagnosis, the treatment of choice was enucleation in five patients (45.5 percent) and transpupillary thermotherapy and observation in one patient each (9.1 percent for both).
Four patients (36.4 percent) were assigned to receive plaque brachytherapy, half of whom experienced tumour regression, followed by the presence of a residual tumour mass that remained stably benign throughout the remaining follow-up period. Two patients experienced radiation retinopathy, which required intravitreal injections of bevacizumab or ranibizumab, respectively.
Almost half (45.5 percent; n=5) of the participants had metastatic disease, which developed at a mean age of 46.6 years. The mean time from diagnosis to metastasis detection was 79.6 months. Median overall survival from the detection of metastasis was 20 months. Only one of these patients survived until the end of the study.
Genetic testing was performed on three patients: one before brachytherapy and two after enucleation. The patient positive for metastasis showed monosomy 3 and mutations in the cKIT gene. On the other hand, the two participants without metastasis showed evidence of monosomy 3 and gain of 3q/8q.
Over a median follow-up of 29 months, seven survivors (63.6 percent) were reported. All four deaths were related to metastasis.
“The reason that the Chinese and Asian-Indians present with ocular melanoma at a younger age compared to other populations is still unclear, and this is of biological interest,” said researchers. “We postulate that the earlier presentation could be due to differences in gene expression profile in Chinese patients.”
“The spectrum of disease mutations in metastasizing UM is rapidly expanding. Going forward, the emerging challenge is practical clinical application of these genetic prognostic factors to risk stratify and individualize surveillance protocols for early detection of metastasis, and discern if selected patients may benefit from prophylactic adjuvant systemic therapy to prevent metastasis,” they added.