Hello Appy5673 and welcome to this forum; I am so pleased you have come here to tell us about what is happening.  What a terrible situation for you  I realise you don't know the cause of his illness but you have to start somewhere and you are welcome here (unless anyone can think of anywhere better!).  I have been looking up other cases where a family member refuses to see his doctor and it sppears the first thing to do is to visit your father's GP surgery and explain to them exactly what is happening and ask if they will do a home visit in the circumstances.  If the receptionist at the surgery is being difficult ask for a phone call from the doctor to yourself in order to discuss the situation.  You need to do this mainly for the sake of your father (and the rest of your family) and also so a doctor can sign sickness certificates for your father's employers.  You need to explain to his employers exactly what is happening; he is probably not getting paid because he has not been sending in sickness certificates.

If the doctor thinks your father is of sound mind (not mentally ill) s/he cannot go against his wishes for treatment.  If the doctor thinks he is not of sound mind then there are things s/he can do to enforce treatment.

I don't think you should give up your studies; if you enjoy your course then follow it - you have a long life ahead of you and I don't think that your father, when thinking rationally, would want you to stop your course.

When your father is being angry, as I understand it, it is probably his illness which is causing the anger although he may not realise that and direct it at the people who love him.

Please come back to us and tell us how things are going - I so much hope his doctor will get to see him.  If eventually you get a diagnosis which has nothing to do with cancer we will point you in the right direction to get support.   Annie