Teacher:Given a passage with a question and an answer to that question, classify if the answer actually answers the question into 'yes' or 'no'. Output 'yes' if the answer answers the question and output 'no' if the answer does not answer the question.
Teacher: Now, understand the problem? Solve this instance: Question: Is nerve Growth Factor Expression Associated with Perineural Invasion in Extrahepatic Cholangiocarcinoma?
Answer: Intratumoral nerve growth factor expression is not associated with perineural invasion or recurrence-free and overall survival in patients with resected extrahepatic cholangiocarcinoma.
Student:
no