Immunomagnetic detection and clinical significance of micrometastatic tumor cells in malignant melanoma patients.
OBJECTIVE
Positive associations between the presence of micrometastatic tumor cells and disease aggressiveness have been reported in several tumor types, but the clinical implications are still not established. We wanted to test a new, sensitive immunomagnetic detection method on bone marrow (BM) and peripheral blood (PB) samples from patients with malignant melanoma and relate the findings to clinical outcome.


METHODS
Samples from 210 patients admitted for relapse of cutaneous melanoma were examined. Mononuclear cell fractions isolated from BM and PB were incubated with superparamagnetic particles coated with antimelanoma antibodies. Live tumor cells with bound beads were isolated with a magnet and identified in a microscope as cell-bead rosettes. Beads without antibody or with an irrelevant antibody were used as controls. The whole procedure was completed within 2-3 h. The identity of the cells was confirmed with a new double labeling procedure with fluorescent microparticles.


RESULTS
Rosetted melanoma cells were found in BM aspirates of 35 of 186 (19%) patients, but in only 2 of 208 (1%) PB samples. The controls were all negative. After a median observation time of 1.1 year (range, 0-6.8 years), patients with tumor cells in BM showed a significantly shorter overall survival from time of BM aspiration (P = 0.009). In multiple regression analysis, a positive BM test was a strong indicator of overall survival (P = 0.021), associated with disease stage (American Joint Committee on Cancer) and with the number of metastatic sites, but not with the primary (Breslow) tumor depth and morphology.


CONCLUSIONS
The results demonstrate the prognostic significance of detecting BM micrometastasis in melanoma patients. The results strengthen the validity of the immunobead technique. In contrast to other techniques, the method identifies intact, live tumor cells that can be further characterized, making the assay attractive for extended use.
Faye
Ragnar S
RS
Department of Tumor Biology, Institute for Cancer Research, The National Hospital, Oslo, Norway.
Aamdal
Steinar
S
Høifødt
Hanne K
HK
Jacobsen
Erling
E
Holstad
Linn
L
Skovlund
Eva
E
Fodstad
Øystein
Ø
D000328:Adult; D000368:Aged; D000906:Antibodies / Q000737:chemistry; D000911:Antibodies, Monoclonal / Q000737:chemistry; D001854:Bone Marrow Cells / Q000166:cytology; D005260:Female; D006801:Humans; D018189:Immunomagnetic Separation / Q000379:methods*; D008297:Male; D008545:Melanoma / Q000097:blood / Q000175:diagnosis / Q000473:pathology*; D008875:Middle Aged; D009362:Neoplasm Metastasis; D012044:Regression Analysis; D012680:Sensitivity and Specificity; D013997:Time Factors; D016896:Treatment Outcome
D000906:Antibodies; D000911:Antibodies, Monoclonal