No dumb questions here, @Abbydog - Usually your Onc or Rad Onc will suggest any trial that they believe suits your particular condition and how you are responding to treatment .....
3.5 years ago, my Rad Onc suggested I go on one where 50% were on placebo & 50% were on a trial drug (that was targeting early stage BC) and I hesitated & stuck with the 'regular' treatment as I couldn't live with myself if I had the placebo & got a recurrence!
They are usually very 'up to date' on what is on offer .... tho the USA BC Sites may mention newer trials that are not yet available to Aussie ..... so if you spot one and mention it to them, they may be able to start lobbying to get the trial started in Australia too, if it would be of benefit to their patients.
Often the trials relate to those with further advanced cancers, to give them more quality of life with less pain & discomfort ...
Any immunotherapy treatment right now is really 'up there' for ALL stages of cancer, as it may stop it in its tracks, if they can get the right mix for those with BC.