Rbc in urine 15-20. Cancer or not?

Sir/mam My sister was diagnosed with rbc in urine..she only once saw blood in urine after which she went to doctor and went for urine test..then the test shown rbc in urine 15-20..but since then she didn't find blood in urine with eyes..but the next 2 test again showed rbc with the same range..i followed up two urologist..both of them said that nothing to worry..drink plenty of waters..also i went through kidney test ultrasound and everything..all the reports were normal.. only abnormality was microscopic rbc in urine..may i know whether there is something to worry or not..also plz tell is she safe..she don't feel any pain while urinating.. everything is normal.. it's just microscopic blood..also tell me is there any chance of bladder cancer or not?