PURPOSE

This study aimed to investigate the plasma expression levels of microRNA-223, microRNA-27b, and microRNA-155 in patients with choroidal melanoma (CM) T_1–2N₀M₀ before and after brachytherapy (BT).

MATERIAL AND METHODS

A total of 41 patients with choroidal melanoma T_1–2N₀M₀ were examined. The mean age was 59.8±15.26 years (ranged 25—81). All patients underwent standard ophthalmologic examination and CT/MRI to exclude metastases. Blood plasma expression levels of microRNA-223, -27b, and -155 were determined using real-time PCR before and after ruthenium-106 brachytherapy at follow-up intervals ranging from 3 to 49 months. In 15 patients, repeat testing was performed at 32—49 months (mean 37.78±5.67 months). Results were expressed as percentages relative to controls (taken as 100%). The control group consisted of volunteers without oncological or inflammatory diseases.

RESULTS

Patients were divided into three groups according to tumor size: small, medium, and large CM. Before treatment, expression levels of microRNA-223 and microRNA-27b increased with tumor growth (p<0.05). No significant differences in microRNA-155 expression were observed between groups. Three months after BT, patients with small CM demonstrated a reduction in the expression of all three microRNAs, which became more pronounced at 12.9±1.3 months (p<0.05). In 10 patients examined 32—49 months after treatment, microRNA expression levels were lower than those in the control group. In one patient with small CM, metastases were detected 48 months after BT; 16 months prior to this, no microRNA deregulation or metastatic signs on CT/MRI had been identified. In patients with medium-sized CM, the decrease in microRNA expression occurred more slowly. In one case, a liver metastasis was detected 5 months after BT; after exclusion of this patient from the analysis, a trend toward decreasing microRNA levels was confirmed in the remaining group. In patients with large CM, no decrease in microRNA expression was observed. Regardless of the degree of tumor regression (complete or partial), the expression levels of microRNA-223, -27b, and -155 remained elevated throughout the follow-up period, which may reflect a persistently high risk of occult metastasis.

CONCLUSION

Analysis of microRNA expression levels in the blood plasma of CM patients can be used to assess the effectiveness of brachytherapy and to monitor patients within the framework of lifelong follow-up.