Tumors (neoplasias) are growths that we, as rat owners, see all too often. Learning about the different types of cancers will help us to identify problems as they occur, treat sooner, and better understand the disease processes involved.

Any abnormal growth, swelling, bump, or lump on your rat can be a potentially serious issue. Rats have a high metabolism and a relatively short life span compared to many other pets. Because of this, diseases can progress quite quickly.

It is essential that you check your rats often, even daily, for any physical abnormalities and that you watch their behavior and their movement for any abnormalities.

This link will give you information about checking your rats: Health Check

Not every lump is going to be a tumor, not every tumor is going to be cancerous, and not every cancer is going to be fatal.
Even so, every effort should be made to have any suspicious growths checked out and diagnosed by your veterinarian as soon as possible.