@wanderingagorist, I would definitely think your salmon diet helped give your dog those extra years, and from everything I've read it definitely seemed the highly processed commercial dry food is one of the biggest causes of cancer, just like all the gmo & processed food sprayed with poisonous insecticides is helping cause cancer in humans. I know that commercial flea & tick products are full of bad chemicals that can be responsible for causing cancer, especially since these are applied directly to the pet, and I also read that toxic tap water can be a cause, probably from heavy metals, chlorine & maybe even the flouride, not to mention all the used Prozak & opioids and pharmaceutical drug waste leaching into the groundwater, slowly compromising all water everywhere, happening more quickly the more people get on manufactured pharmaceutical drugs. Also vaccines seem to be another major cause of some types of cancer in dogs...

The main environmental causes based on my research seem to be lawn & garden insecticides, lawn fertilizers, and chemicals found in non-natural household cleaners. Probably big-city pollution too, but that's a moot point where I'm at in a rather small town. Any chemical spray on the lawn or chemical cleaner on the carpet indoors is particularly bad because the dog's nose is usually so close to the ground. Second-hand smoke is also a cause of lymphoma in dogs (what I was personally fighting), as well as chemicals in the environment. Hope my response was helpful. You're right though, diet seems to be the main thing - with the right diet & healthy immune system the body is typically strong enough to fight it off on its own even if it forms. Once the body is compromised by bad diet or environmental poisons, it becomes that much easier for the cancer to find an opening to spread and start taking over, or to begin forming in the first place...

Glad to hear your dog beat the odds to live a few more years - that's amazing! Sadly mine didn't stand a chance as we just got to the cancer too late and the vet also thinks it was an extremely aggressive form of lymphoma moving particularly fast. And this is a dog who hadn't once gotten sick in her entire 9 year life until she got cancer - it just doesn't seem right. Feel free to check out my blog post documenting the story of our fight which we sadly just lost, as Pepper passed away the evening I was planning to conclude and post our story to Steemit, the night before last. At least she went as peacefully and painlessly as possible with me by her side. Post also has some embedded links to articles talking about causes of cancer in dogs you might also find interesting: https://steemit.com/blog/@jasonliberty/when-the-vet-gives-your-dog-1-3-days-to-live-every-healthy-day-is-a-gift-fighting-cancer-naturally

Thanks for the interaction, take care & have a wonderful day!