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ABSTRACT.Purpose: To evaluate whether tumour therapy for malignant uveal melanoma leads to a shedding of melanoma cells into the systemic circulation. Methods: Ninety-four peripheral blood samples from 81 patients with malignant uveal melanoma were collected before and after different tumour therapies and the number of circulating melanoma cells (CMCs) was investigated (seven patients with enucleation, 49 patients with stereotactic radiotherapy, 19 patients with endoresection of the tumour, 15 patients with ruthenium-brachytherapy and four patients with transpupillary thermotherapy). A cellular approach was used to detect CMCs through an immunocytological assay with tumour cell enrichment by immunomagnetic cell sorting. The number of CMCs was analysed further according to specific patient characteristics, tumour parameters and the development of metastasis. Results: There was no significant difference between the number of CMCs before and after the different therapies (p = 0.78). There was also no significant association between established prognostic parameters of primary uveal melanoma and the detection of CMCs (all p >0.05). The number of CMCs was not related to the development of metastasis in a short median follow-up time of 16 months (p > 0.05). Conclusion: No changes in CMC values were observed before and after different tumour therapies. In the majority of cases therapy does not lead to a shedding of detectable melanoma cells into the systemic circulation.

We developed a cellular approach to the identification of circulating melanoma cells in peripheral blood using immunomagnetic cell sorting. One hundred seventy-eight blood samples from 129 melanoma patients and 30 samples from healthy persons and nonmelanoma patients were examined. After density gradient centrifugation the interphase was incubated with the mAb 9.2.27. Positive cells were labeled with magnetic microbeads and enriched by immunomagnetic cell sorting. Cells were stained using an alkaline phosphatase-antialkaline phosphatase assay and examined by light microscopy. In spiking experiments, melanoma cells seeded at a concentration of one melanoma cell per ml whole blood could be detected reliably with the assay. Circulating melanoma cells were not found in 30 controls examined, nor were 9.2.27-positive cells found in 41 patients with primary malignant melanoma. In patients with regional lymph node metastases and in patients with disseminated disease, circulating 9.2.27-positive cells could be detected in 3 out of 22 patients (13.6%) and 10 out of 66 patients (15.2%) examined. We present a sensitive and specific immunocytological approach to detect circulating melanoma cells in peripheral blood. The method is not suitable for early detection of metastases but is a valuable tool for further investigating biological characteristics of circulating melanoma cells.

We developed a cellular approach to the identification of circulating melanoma cells in peripheral blood using immunomagnetic cell sorting. One hundred seventy-eight blood samples from 129 melanoma patients and 30 samples from healthy persons and nonmelanoma patients were examined. After density gradient centrifugation the interphase was incubated with the mAb 9.2.27. Positive cells were labeled with magnetic microbeads and enriched by immunomagnetic cell sorting. Cells were stained using an alkaline phosphatase-antialkaline phosphatase assay and examined by light microscopy. In spiking experiments, melanoma cells seeded at a concentration of one melanoma cell per ml whole blood could be detected reliably with the assay. Circulating melanoma cells were not found in 30 controls examined, nor were 9.2.27-positive cells found in 41 patients with primary malignant melanoma. In patients with regional lymph node metastases and in patients with disseminated disease, circulating 9.2.27-positive cells could be detected in 3 out of 22 patients (13.6%) and 10 out of 66 patients (15.2%) examined. We present a sensitive and specific immunocytological approach to detect circulating melanoma cells in peripheral blood. The method is not suitable for early detection of metastases but is a valuable tool for further investigating biological characteristics of circulating melanoma cells.