RET and neoplasm: In this study, we applied interphase FISH on a subset of post-Chernobyl tumour that became clinically apparent within a short period of time after exposure to radiation (4–8 years) and compared the data generated with that from a group of papillary cancers with a longer latency (9–12 years), in order to study the pattern of rearrangement of the RET oncogene within these two groups.