In this cancer charity speech you will say that this is a disease that affects virtually everyone at some stage. You will point out how widespread the disease is and that if people don’t experience it themselves, then almost certainly a family member or close friend will.
You will speak about the huge problems cancer can cause, both physically and emotionally, and of how important it is, therefore, that as a caring society we do everything we can to treat and hopefully eliminate it. You will praise the people working in the field (either of treatment or research, as appropriate) and praise the donors who make their work possible.
You will thank the organizers for their hard work and may wish to end with a toast to either the hosts or beneficiary of the event. A short, sincere poem may bring poignancy to your cancer charity speech.