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A total of 109 prospectively sampled cancer patients , receiving the first treatment with an EGFR inhibitor , were genotyped for functional EGFR polymorphisms and tagging variants in genes involved in receptor downstream signaling .
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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