The Results of Stricter Inclusion Criteria in an Immunomagnetic Detection Study of Micrometastatic Cells in Bone Marrow of Uveal Melanoma Patients - Relevance for Dormancy.

Approximately 50% of uveal melanoma patients develop metastases. We want to evaluate the effect of stricter criteria on our data from our previous study correlating survival and bone marrow (BM) micrometastasis results using our immunomagnetic separation (IMS) method. Mononuclear cell fractions (MNC) isolated from BM were examined for tumour cells and the patients were classified as BM positive (BM+) or BM negative (BM-). The study originally included 328 consecutive patients with uveal melanoma from 1997 to 2006. The cohort was limited to 217 patients when we introduced cyto- or histopathological verification of melanoma cells in the patient as a main new criterion for inclusion. Tumour cells were found in BM-samples in 38.7% (95% CI, 32-45) at enrolment. Until the latest work-up 43.8% (95% CI, 38-50) of patients had developed melanoma metastases. After a minimum follow-up time of 8.5 years, 60.4% (95% CI, 54-66) of patients had died. The causes were: melanoma metastases 69.5%, another type of cancer 5.4% and non-cancerous causes 19.5%. Overall median survival was shorter for the BM- patients (11.3 years) (95% CI, 10-12) compared to the BM+ (16.5 years) (95% CI, 12-14), p = 0.04, log rank test. All-cause mortality and specific melanoma mortality estimated after 12 year follow-up showed a highly significant difference comparing BM- and BM+, p = 0.010 and p = 0,017, respectively. IMS yields a high fraction of BM+ samples due to micrometastasis at diagnosis and these cells appear to have a positive prognostic impact strengthening our previous report. The late recurrences support the concept of tumour dormancy.

Disseminated tumour cells in bone marrow of patients with uveal melanoma.

PURPOSE: Approximately 50% of patients with uveal melanomas develop metastases. Thus, it is important to improve our understanding of how melanoma metastases develop. METHODS: As part of a uveal melanoma micrometastasis study, we compared the detection rates of immunomagnetically selected (IMS) tumour cells in bone marrow (BM) with positively stained tumour cells using immunocytochemistry (ICC). Bone marrow mononuclear cells were isolated. Immunocytochemistry cytospin preparations were immunocytochemically stained in parallel with two different melanoma antibodies, 9.2.27 and HMB45. Using IMS, melanoma cells were selected from BM mononuclear cell fractions using immunomagnetic beads coated with the 9.2.27 antibody and identified by light microscopy. RESULTS: In cytospin preparations from 226 patients, melanoma cells were detected in 24 (10.6%), 10 with 9.2.27 and 17 with the HMB45 antibody. In three cases, we found positive cells with both antibodies. Six of the 226 (2.6%) patients that stained positively with ICC died with metastatic disease, all also positive with IMS. Sixty-six (29.2%) patients had positive BM samples with IMS at the first examination. Immunomagnetic selection (IMS) was positive in 36.8% of the 57 patients who later developed clinical metastases. Twenty-one IMS-positive patients and 31 IMS-negative patients died of metastases, in total 52 of 226 patients (23.0%). The mortality rate of melanoma metastasis was 24% (6/24) after at least 4 ½ years in ICC-positive patients compared to 38.5% (20/52) in IMS-positive patients. CONCLUSION: The presence of melanoma cells in BM of patients with uveal melanoma is documented in our study with IMS and ICC. Immunomagnetically selected is more sensitive than ICC in detecting tumour cells in BM. However, statistically, we did not find any prognostic impact of the presence of melanoma cells in BM.