Hi. I worked with a vet 8 years. If this were my dog, and the lump didn't appear painful or causing some other problem, I would leave it alone, just keeping tabs on it to make sure it wasn't getting bigger. If that happens and surgey is the last option, I say go for it. Anesthesias used today are VERY safe, even for an older dog. Your dog would be 'fasted' (no food) overnight, then given a shot of morphine to help her remain calm. She will be taken to surgery, and ketamine given to render her unconsious, then a breathing-anesthesia tube inserted in to her esophagus. She will then recieve either propofol or isoflourane in gaseous form. Surgery will be done, and she will be watched closely while waking up. I have seen thousands of dogs fly through surgery with blue ribbons. I can only count on one hand the amount of times I saw one die in eight years. But your vet is bound by law to tell you that the surgery is risky for this reason. Even rare, it can happen. And it most likely will not, if your dog is otherwise healthy. :)
Thank you so much for your advice, i appreciate it a lot.