Anniston
As you noted SCBC is rare & aggressive. A suggestion of "no additional treatment" can be hard to accept without a seeking a second opinion.
The National Cancer Institute (NCI) is currently sponsoring a clinical trial, "Testing the Effectiveness of Two Immunotherapy Drugs (Nivolumab and Ipilimumab) With One Anti-cancer Targeted Drug (Cabozantinib) for Rare Genitourinary Tumors.
Rare includes : Bladder Adenocarcinoma, Bladder Mixed Adenocarcinoma, Bladder Small Cell Carcinoma, Bladder Squamous Cell Carcinoma, Chromophobe Renal Cell Carcinoma and others.
The study identifier is NCT03866382 (the 0 is a zero) and the web site for more info is:
clinicaltrials.gov/ct2/show/NCT03866382
There are many locations taking part in the study. These are the people working on the rare cancers. Perhaps you can make contact with the principal Investigator at a site near you and learn more about what the study involves and how it impacts older frail patients.
In seeking information about clinical trials that might accept me, I found it was tough to get answers, calls were seldom returned, but once I did establish contact the insights I gained made the effort worth while.
I am not sure that this is what you were hoping for, but I hope it helps.
General info about clinical trials is found starting at Clinicaltrials.gov
Best,
Jack