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Two groups of patients were selected : the first group suffered from epithelial serous ovarian tumors and the second group suffered from benign ovarian lesions ; ovarian tissue samples from all the subjects ( benign and malignant ) were subjected to methylation - specific polymerase chain reaction for methylated and unmethylated alleles of the genes ( E - cadherin , p15 , and p16 ) .
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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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