Thanks for your query.
Passing blood in the urine may be due to many causes. But mostly it might be due to bladder tumors and kidney
tumors. sometimes due to stone disease and also after chemotherapy
). You had already mentioned that your brother is having colon cancer
infiltrating into bladder. So now his problem of blood in the urine is mostly due to this infiltration. The chances of new bladder tumor to occur is rare but still may occur. you can get an ultrasound
of the abdomen to see if there are any other lesions in the bladder apart from this infiltration. If there are any other lesions then they an be further worked up.