My cat keeps quacking.

My 14 year old colour point persian Coco has for the past year now taken to, what sounds like, quacking around the house. She'll sit there and quack, almost as though theres something stuck in her throat. &Whatever it is, she keeps swallowing it down.
I've tried rubbing her throat softly and patting her back to try and coax her to let it up but she has none of it.
She does indeed have mammery cancer, but she was quacking long before the cancer came along. Or, so we believe.

I've tried googling quacking cats and all I get are jokes and such.
I guess you could call it coughing, but it really doesn't seem much like coughing as its clearly evident theres something trying to get out.

I was wondering if anyone knew anything about what this is?
Thanks a bunch and such.

I would take her to the vet to have her throat checked out. If she, indeed, has mammary cancer, then you really need to rule out a metastatic mass to the throat. If she has a mass, this could become a serious emergency very quickly.

Go to the Vet it could be in her Lungs and Throat.

I'd also suggest a vet. It could be something simple, like a hairball, or it could be a dental issue or possible related to the cancer. With so many possibilities, a vet visit can help rule out the more serious issues.