My mum is now having trouble swallowing. It means she is not getting her cancer medication properly (her bone marrow cancer has been kept in check since 1992), and they are looking for different meds that is administered differently. She is 82, and the decline has been slower the last few years. The ability to chew and slow seem to be declining fast now.
The new cancer meds will give different side effects that she will be unable to communicate as she is no longer verbal, and may not be viable. We will have to decide whether to continue or stop medicating her.
If the OP was me, and in my shoes, she would probably just say "to hell with it, mum is old, has cancer and dementia, lets stop the meds, lets stop being a burden on society." But it is not that simple.
Stopping her medication, which are keeping her white blood platelets on an even 600 (400 should be ideal) will cause the levels to rise (we tried two weeks off medication to see what happened, and the levels rose to 1300, and mum has burst blood vessels throughout her face and struggles to keep awake). Two things may happen if the levels rise. Her blood will either thicken and clot, causing blood clots and possibly stroke. Alternatively her blood may become really thin and cause a brain hemorrhage, and possibly stroke. It may not kill her, just make her more disabled and in need of more care.