There is something else we should know. Allison recently lost Bubbles not long after joining our group. It's in Grief but I know a lot of people like me find that a painful forum to look in. Sorry for bringing that up Allison but that emotional loss will affect how things go with Mor Mor.
Maggies Mom Debby is right, we need more information. How old is Mor Mor, any family history you can provide, previous medical conditions (even things you think might not matter), any oddball thing he has ever swallowed or gotten in to, diabetic or not.
What exactly did the vet say? I ask this because over many years I've had vets say vague things like "This doesn't look good/I would recommend a super-expensive test" and I've even had an oncologist who was in tears and never actually said the word cancer. When I said "So treat her like a Princess and let her eat whatever she wants" she just nodded and promised to fax the files to my vet.
Diagnosing cancer requires either a slide of cells under a microscope or actually seeing something unmistakable through a scope or invasive surgery. Just because there is a 90% chance of something does not mean that's what it is.
An enlarged bladder could be caused by a lot of things. An enlarged bladder can be felt by hand if the vet is experienced and seen on X-ray. Moving beyond your vet's X-ray (I hope it's digital, some vets still use film) there is ultrasound, SPECT scan, CT scan (sometimes still called a CAT scan) and MRI. All of these scans still require someone to interpret them, it's not just a yes/no thing. One good thing about ultrasounds is that they are portable and in my Noah's case the tech came to my vet's office and there was no need for sedation. CT and MRI require full anesthetic because Mor will have to be perfectly still and MRI's are just incredibly noisy. I've had four of them.
Money is a touchy subject. Don't fall for a guilt trip "Well if you really love your cat..." because we put Jasper through an MRI and a spinal tap, almost $4,000, and it was all for nothing.
Now, I've said some things that are speculation on my part. If anyone wants to correct me please do so, this is not about me. A 90% chance of cancer means a 10% chance it's not. There's a good reason we're not supposed to dispense this kind of advice so I wanted everyone to see this. These are things that have happened to me, my wife and our cats and dogs but obviously I'm not a doctor.
One more thing. Did Mor get X-rayed again after your vet expelled urine? Was his bladder still enlarged? Does anyone know if the expelled urine should be examined for cancer cells?
I'm honestly trying to help and I know you've just been put through Hell with Bubbles. Thoughts anyone?