Sounds like it became known and he was told the risks were low.
It was discovered after the transplant. Too late to do anything at that point, except to watch out for the cancer and treat it. My sister has been battling re-current endometrial cancer for more than a year and a half. She’s gone through 2 surgeries, radiation, and most recently completed chemo. Her recent CAT scan was negative of ca anywhere in her body! This is truly a praise report! (praise God!)