Well, it looks like things are worse than originally thought. Although it did not show up on the MRI (generally just big things show up), it appears that I have a 'dusting of cancer cells at the base of my spine on the cauda equina, where all the nerve endings that deal with the legs come out.
And, it appears, based upon observational symptoms alone, that the cancer has invaded my cerebrospinal fluid. This is a very difficult thing to treat because chemotherapy to the CSF would have a significant impact on my quality of life. So no more chemo, but I am receiving 5 rounds of radiation in the saddle back area to try to relieve symptoms such as pain. I now wear a pain patch and use additional pain drugs when there is break through pain. Wish I had better news.