Autumnplanner,
Welcome. I am not sure there is any definitive answer to the question of how many are cancerous. What you have described is probably a papillary growth. Sometimes they are benign or symptomatic of something else although I would guess the majority are a cancerous growth.
If there is anything I have learned with several other health issues is: "take it one day at a time". Easy for me to say now that I am healthy. That is all we can control. After the cystoscope your husband likely will be scheduled for a TURB (transurethral resection of the bladder) which is fancy words for a biopsy under a short anesthesia. He is fortunate to have a caring wife and caregiver. You still won't really know much until AFTER the pathology tells you what this actually is. Speculation is wasted effort. So, patience is the word. If this is bladder cancer it is very treatable and beatable.
