But that's not evolution as you don't pass the cancer on, i.e. your sperm doesn't get created with the cancerous dna.
Older males actually cause most change as their dna replication is not as good as when younger so a higher chance of a mutation at conception. This is not the case with women though whose eggs are formed at birth.
Philosophically speaking cancer is a strange thing. It's own success brings on it's own demise and therefore brings into question what is life about,. (not in the 7 characteristics explanation). Cancer seems to show that we are a collection of co-operating cells but in an accidental way where each cell is 'selfish'.