20201
Background : We previously identified two highly discriminating and predictive radiation - induced transcriptomic signatures by comparing series of sporadic and post - radiotherapy thyroid tumors ( 322 - gene signature ) , and by re - analyzing a previously published dataset of sporadic and post - Chernobyl thyroid tumors ( 106 - gene signature ) .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
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