I don’t believe the cover story about them being “discovered” during the fall. There’s ample evidence that she’s been being treated for cancer for more than a year (gloves, numerous absences). I suspect its far more advanced than the cover story that’s even being willfully fed to the compliant NYT.
Are these metastatic? Given her history, they likely are. I doubt they'll tell us.
When a surgeon states that there is no evidence of it spreading, it doesn’t really mean much. At best, they haven’t detected other places it has spread to.
The cancer treatment was not a secret. The fact that it’s in her lungs (and probably in her bones) was news.