Hypercalcemia + weight loss

Our 5 year old female cat (spayed) started to lose weight about 6-8 months ago. She has went from 13lbs to 8.9lbs. She has had a decreased appetite and decreased energy but otherwise normal stools and behavior. We took her to the vet for some blood tests and everything came back normal except she was hypercalcemic. The vet immediately went to cancer as the most likely diagnosis. We have an abdominal ultrasound scheduled for tomorrow.

Has anyone has any experience with symptoms like this in their cats and what was the outcome? Are there some other diagnosis that could be causing weight loss and hypercalcemia? Would really appreciate any help or input. Thank you!