22657
Results : One hundred and seventy one papillary thyroid cancer patients were included ( mean age 45 +/- 16 yrs , followed for a median of 4 yrs after initial treatment ) .
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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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