Do people have the right to know their diagnosis and prognosis as well as anything else connected with their condition, their treatment and its consequences? What ethical principle supports this...

Do people have the right to know their diagnosis and prognosis as well as anything else connected with their condition, their treatment and its consequences?  What ethical principle supports this "right"? Explain how the principle supports the "right" as a "good" thing.  If not, why not?