I read some frightening stats a little while ago: 45% of dogs over the age of 10 will die of cancer, and a recent study has shown that 63% of Goldens die of cancer. Yikes. Causes are largely unknown, but there is thought that excessive carbohydrate intake in over-processed dry food diets can play a role in some dogs. Good for you for wanting to provide better nutrition for your pup. You might want to research raw a bit more, it's not as dangerous as you think. Here's some good info:
http://rawfed.com/