How long do dogs that have cancer live for?

my dog has a lump on his foot and they did tests and have said it is a cancer tumour... 

were going tomorrow to talk about the options but im just wondering if you dont get any treatment and just let the dog die naturally how long do they live for? 

or how long does it take for them to get really ill and NEED to be put down? 

hes already had the lump for about 6 months and he seems absolutely happy and in no pain atall... 

btw hes a lurcher (if that makes a difference atall ?) 

thanks.

 Best Answer:  I think it's hard to say. It depends mostly on the type of cancer, but also on things like whether or not it's spread to adjacent lymph nodes/organs and also on the dog breed. 

I wouldn't jump the gun just yet. Earlier this year what we thought was an infection from a split toenail turned out to be squamous cell cancer (even the initial biopsy had it wrong). We know it was SCC because we got the toe amputated and they checked again on the removed toe. It's been a couple months now and he's back to his energetic self for the most part (he's 10)