Purpose: Numerous studies of circulating epithelial cells (CECs)have been described in cancer patients, and genetic abnormalities have been well documented. However, with one exception in colorectal cancer, there has been no report of matching the genetic abnormalities in the CECs with the primary tumor. The purpose of this investigation was to determine (a) whether CECs in patients including those with early tumors are aneusomic and (b) whether their aneusomic patterns match those from the primary tumor, indicating common clonality.
Experimental design: Thirty-one cancer patients had CECs identified by immunofluorescence staining using a monoclonal anti-cytokeratin antibody. Their CECs were analyzed by enumerator DNA probes for chromosomes 1, 3, 4, 7, 8, 11, or 17 by dual or tricolor fluorescence in situ hybridization. Touch preparations of the primary tumor tissue were available from 17 of 31 patients and hybridized with the same set of probes used to genotype the CECs.
Results: The number of CECs from each patient ranged from 1-92 cells/cytospin. CECs showed abnormal copy numbers for at least one of the probes in 25 of 31 patients. Touch preparations from the primary tumors of 13 patients with aneusomic CECs were available. The pattern of aneusomy matched a clone in the primary tumor in 10 patients.
Conclusions: We conclude that the vast majority of CECs in breast, kidney, prostate, and colon cancer patients are aneusomic and derived from the primary tumor.