Definition: 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.
Input: Question: Is pattern of first recurrent lesions in pancreatic cancer : hepatic relapse associated with dismal prognosis and portal vein invasion?
Answer: Hepatic relapse was associated with a dismal prognosis and with pathological portal vein invasion. Novel therapeutic strategies are therefore required to reduce the incidence of hepatic relapse, especially in patients with portal vein invasion.
Output:
yes