Noni, At this point you do not have a cancer diagnosis - there are non-cancer causes for a blockage in the ureter. Most important is to find out what is causing the blockage.
I copy my earlier reply in the forum to another person who had trouble finding information on ureter blockages / cancer:
"Ureter Cancer is frequently called Upper Tract Urothelial Carcinoma or UTUC. Using all three terms on google will provide many responses.
One recent drug approval for Low Grade Upper Tract Urothelial Carcinoma (LGUTUC) is "Gelmyto", a form of Gemcitabine.
I have had only one kidney since the 60s, thus there has been concern about the possibility of UTUC ever since the bladder cancer diagnosis; thus my interest in UTUC.
Not all ureteral cancers are from the bladder, as you have suspected. Independently, after bladder cancer was diagnosed I was found to have an unrelated Renal Cell Cancer in my one and only kidney. That cancer was described as having the potential to spread downstream to the ureter and bladder. Fortunately, the kidney cancer was successfully (so far) removed.
Maybe it is just me, and my situation, but I would want additional opinions and thoughts on how to address the ureter tumor problem before considering losing a kidney. Reliable sources on google (Cancer Society, well know major medical institutions, etc) will offer possibilities to discuss with your care team about ureter treatment."
Also, google search on "distal ureter" and "ureter blockage" and "Ureteroscopy". I hope this helps.
Best
Jack