Congratulations on being selected to speak at your Relay, it's an honor. I am a Hero Of Hope Speaker for the American Cancer Society and Relay For Life. I have given many speaches to various groups. If they have not given you a topic, you should speak to what is personal to you. Describe how you were diagnosed, then give the reader's digest condensed version of your treatments, how your doing now, how has cancer affected your life, how has support groups like WhatNext and resources at the American Cancer Society helped you, then close out with your hope for the future.
Here are a couple of links to me giving my presentation to Relay groups. http://youtu.be/QgY_IxoF46o Jackson Tn. for Super Saturday event
http://youtu.be/i68M-nE02dc In Nashville, Tn. for Team captain's university.
Please email me gregatwhatnext.com if you need any help getting your presentation together.