I am very sorry. They look like large mammary tumours - but you can see what a vet says …. if not removed, they will soon grow so large that she will need to be humanely put to sleep by a vet that knows how to do it properly - most do not
(gas/oxygen mix used for surgery, when unconscious to at least a surgical level - vet will test eye reflex and gently pinch toes - then she will be injected and kept unconscious with the gas/oxygen mix until dead. You will need to make sure it is done properly and stay with her if possible)
http://ratguide.com/health/neoplasia/mammary_tumor.php