You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is Which of the following is not a tumor marker: and explain in detail?
Human leucocyte antigen A2 REF: Harper biochemistry 25th edition page 809, (American cancer society) http://www.cancer. org/acs/groups/cid/documents/webcontent/003189-pdf.pdf, http://en.wikipedia.org/wiki/Tumor_antigen, See APPENDIX-26 for list of "Tumor markers" A tumor marker is a substance found in the blood, urine, or body tissues that can be elevated in cancer, among other tissue types. An elevated level of a tumor marker can indicate cancer; however, there can also be other causes of the elevation. Tumor markers can be used in a number of ways. Screening and early detection of cancer Diagnosing cancer (CA 125 for ovarian cancer, AFP for liver cancer) Determining prognosis for ceain cancers Staging the extent Monitoring the treatment Detecting recurrence