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: Does vascular density predict future metastatic disease in clinical stage 1 non-seminomatous germ cell tumours of the testis?
Answer: We confirmed the value of vascular invasion as a prognostic marker in stage 1 NSGCT. Tumour vessel density was of no prognostic value. Two factors may contribute to this. First, there was wide variation of vessel density between different blocks of a tumour. Second, the most vascular area in a tumour was frequently in low-grade tumour.
Student:
no