Encrusted Stent, Low Grade tumour Uterer & Kidney

My Sister was diagnosed in 2020 with High Grade Urothelial with Lamina Propria Invasion and CIS stage pT1 which was removed in Sept 2020, follow up cystoscopies were NED till December 2023 when a Low grade Non-Invasive Papillary Urothelial Carcinoma grade 1-2 TCC pTa was removed. A stent was inserted in the uterer then, and she has just had her appointment to have the stent removed ( 18/3/24) and the Dr said that the stent was encrusted and that there were now tumours in her ureter and her kidney! we have an appointment with the Dr on Monday to get the pathology report from the biopsy taken. The Dr "thinks it looks the same as the tumour he removed in December, Low Grade). He said at the hospital that he would recommend the removal of her kidney and ureter! my Sister was absolutely in shock to say the least as there had been NO mention of any problems with her ureter or kidney beforehand. He also said that her actual bladder looked really good. So I have been trying to do some research and I have seen where it has been known for cancer to seed in the ureter when a stent has been used???? so I would be very appreciate if anyone has any knowledge of this happening or have had it happen to them.

Thank you all in advance, we are just so stressed and confused at the moment.