We did some searching and found this on Merck:
Salivary Gland Tumors
Salivary gland tumors are rare in cats, although cats are affected twice as frequently as dogs. They usually occur in cats more than 10 years old. Most salivary gland tumors are malignant, with carcinomas and adenocarcinomas the most common types. Spread to nearby lymph nodes and the lungs is common. Tumors removed by surgery alone tend to recur, so radiation treatment, with or without surgery, offers the best outlook in most cases.
So, it doesn't sound good. Dr T wanted to send off the slides to be tested elsewhere since it is pretty rare. Mom told her to go ahead, though it won't really change much unless it comes back non-cancerous for some reason. They are going to hold off on doing anything until they here back from the secondary test - maybe mid-week. However, based on his age, the goal is to keep him comfortable and maybe try to reduce the swelling at the back of his jaw. Mom told Dr T that she isn't sure if it is getting bigger or if it just that she has been staring at it for a week.
No idea what this means for time....they did discuss maybe trying to aspirate part of it to relieve some pressure but not sure if that will happen or not. The main goal is so long as he seems comfortable and still eating then we will give him all the time he has.