How does bladder cancer travel to

I found out I had bladder cancer 12/31/15. I was told it was t1 high grade and it was not in the muscle. I was told to take vitamin c and come back in May . Cystoscope showed 2 bb sized areas and a reddened area. Doctor said he may want me to do chemo. The results was p1 high grade...no muscle propria to test. I went back to my 12/31/15 results and read it...it also showed no muscle propria present. How could the doctor tell me it was not in the muscle???

He sent me to an oncologist for chemo. Oncologist was confused why I was there since no muscle tested and I had not been staged. She referred me for a 2nd opinion at Emory Clinic. The doctor there said he could not explain why FORMER urologist sent me for chemo even though I had not been staged. He set up blue light cysto at the hospital for the next week.

This did have muscle propria with all 3 specimens submitted. 2 were CIS with no muscle invasion and one was urothelial cell with no muscle invasion. New doc was going to set up for bcg but I had a new issue. My left lower back had been hurting since after May cysto. Bone scan and ct scan had shown degenerative area L5 - S1. So I went to orthopedic doctor thinking it was something like arthritis. They sent me for mri. It showed a left lumbar Paraspinal lesion. Emory urologist set me up for biopsy. Biopsy showed metastic bladder cancer. So I am at stage 4.

Now I am starting radiation next week and chemo on the 22nd....and I am totally confused. How did the cancer travel to back without invading my bladder muscle???

Thank you,
Rebecca