My experience:

You may need a referral letter. In my case, the referral letter was from private hospital.

Govt Hospital - Make an appointment to see the specialist. Once received confirmation from the doctor, they will refer to a group of specialist (the operation not just involve oncologist, but few specialist)
and then they will decide whether to proceed or not. if its too risky, then they decide not to go for operation. if yes, they will proceed ASAP.

my experience for cancer removal surgery. PM for details. Thank you.