You can TRY to sue, but there's only one problem:
You have to PROVE ~ and I do mean PROVE ~ your father was IRREPARABLY HARMED by the first hospital.
How was your father harmed? What harm did the hospital cause to your father that could not be repaired by someone else? Aside from having to go to another hospital ~ where you took him and he was properly diagnosed, on the same day, so there was NO DELAY IN TREATMENT --- do you see what I'm getting at? Where is the HARM? There is none.
By the time this goes to trial, and they'll probably let this one go to trial because there WAS NO HARM, your father may be cured of his Cancer, or he may die from it. Either way, it's going to take years to get to Court. You need to think about what your father's energy needs to be focused on: fighting a hospital he cannot defeat, or beating his Cancer?
I know you're angry; you have every right to be angry about the way you were treated. But the fact is the first hospital DID NOT GIVE him Cancer. HE already HAD Cancer when he went there; they simply failed to detect it. Had you taken your father home and allowed him to stay there, undiagnosed and untreated, and he'd died from that Cancer, then you'd have a case for Medical Malpractice.
Since you DID NOT follow their orders ~ since you took your father to another facility and got him properly diagnosed and treated the same day ~ THERE IS NO HARM. You cannot prove they caused you anything more than an inconvenience ~ the inconvenience of going to a second hospital.
They delayed his diagnosis by what -- a couple of hours? In the long-run, that makes no difference. Had they delayed his diagnosis by a couple of weeks, or months, or years -- that would have made a difference. But that didn't happen.
File a complaint about how you were treated; you have that right and responsibility. But you do NOT have a legal case for Medical Malpractice. I'm sorry. They did not cause permanent harm to your father. You prevented that from happening ~ thank goodness.
Former Employee of Medical Malpractice Attorney