Cancer is the #1 disease-related cause of death for dogs and cats.
I came across this website with a lot of facts and useful information on the subject ranging from causes of cancer to early warning signs to links about cancer care. There are also some very good tips on how to minimize your pet’s risk. Essential reading for pet parents!
Check out the website.

PCA looks like it’s owned by a dog food company, Blue Buffalo, which is fine, as long as they’re not using it to market their food as being “cancer preventative”. The founder of Blue Buffalo had an Airedale Terrier named Blue who died of stomach cancer, I believe. The biggest cancer preventative IMO is not over-vaccinating our pets. So I am glad they do mention this on the website: (copy/pasted)
Over-Vaccination It has been clinically proven that over-vaccinations can weaken the body’s immune system and set the stage for cancer. In fact, in cats there is now a specific type of cancer that is named “Vaccine Induced Fibro Sarcoma” which comes as a side effect of and at the location of the vaccine injection.