20204
Results : We found that the 5 genes common to the two signatures classified the learning / training tumors ( used to search these signatures ) of both the post - radiotherapy ( 7 PTC ) and the post - Chernobyl ( 6 PTC ) thyroid tumor series as compared with the sporadic tumors ( 7 sporadic PTC in each series ) .
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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:
 None