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.

Question: Is vinorelbine an effective and safe drug for AIDS-related Kaposi 's sarcoma : results of a phase II study?
Answer: Vinorelbine is safe and effective in the treatment of patients with advanced KS who have been previously treated with one or more chemotherapy regimens.
yes