1. ¹Institute of Molecular Radiobiology, GSF-National Research Center for Environment and Health, Neuherberg, Germany
2. ²Institute of Endocrinology and Metabolism, Academy of Medical Sciences of the Ukraine, Kiev, Ukraine
3. ³Institute of Pathology, GSF-National Research Center for Environment and Health, Neuherberg, Germany
4. ⁴South West Wales Cancer Institute, Singleton Hospital, Swansea, UK

Correspondence: Dr H Zitzelsberger, Ingolstädter Landstr. 1, Neuherberg, D-85764 Germany. E-mail: zitzelsberger@gsf.de

⁵These authors contributed equally to this work.

Received 8 November 2005; Revised 2 March 2006; Accepted 21 March 2006; Published online 25 April 2006.

Abstract

Tissue samples from 13 post-Chernobyl childhood thyroid tumours that occurred within a short period of time (4–8 years) after the Chernobyl accident have been investigated by interphase FISH analysis for rearrangements of RET. In all, 77% of cases showed RET/PTC rearrangements and a distinct intratumoural genetic heterogeneity. The data were compared to findings on 32 post-Chernobyl PTCs that occurred after a longer period of time (9–12 years) after the accident. In none of the cases from either group were 100% of cells positive for RET rearrangement. In addition, the pattern of RET-positive cells was different in the two groups (short vs longer latency). A significant clustering of aberrant cells could be detected in the long-latency subgroup, whereas the aberrant cells were more homogeneously distributed among the short-latency tumours. The findings suggest that oligoclonal tumour development occurs in post-Chernobyl PTCs. This pattern of different clones within the tumour appears to become more discrete in cases with longer latencies, suggesting either outgrowth of individual clones or development of later subclones with time.