Background: The mechanism of multistage carcinogenesis initiated by environmental carcinogens produces clonal evolution of initiated cells to the stage of metastasis. However, the simultaneous co-existence of various cell clones is not excluded. The analysis of chromosome alterations appears to be the best method to assess the clonal composition of a tumor.
Material/Methods: Laryngeal tumor specimens and their corresponding metastases to the adjacent lymph nodes (20 pairs) were analysed by comparative genome hybridization (CGH).
Results: The profile of gains and losses of DNA copy number was found to be fairly similar in the primary tumor location and in its metastasis. In this study the most frequent losses were found on 3p, 5q, 9p, 13p, and 13q, while gains occurred in 1q, 3q, 5p and 11q. The gains and losses were found more frequently in metastasis than in primary tumor, except for the loss of 3p and the gain of 5p. The biological function of the latter chromosome alterations seems to be limited to tumor growth, rather than metastasis formation.
Conclusions: A comparison of the profiles of chromosome alterations in primary tumor locations and metastases indicate that the progression of laryngeal cancer is connected with the clonal evolution of tumor cells.

Keywords: clonal evolution, metastases, molecular cytogenetics, laryngeal cancer