MY FIRST POST & ?'s about radiation

Was diagnosed with Wilm's tumor in 1969. Had complete left nephrectomy. Received vincristin and cosmagen chemotherapies and cobalt treatments. Now 43 years later I have been diagnosed with clear cell renal carcinoma with a 4cm tumor on right kidney and it matastisized to S1 & L5 with approximate 4 cm tumor. Tumor has been removed from spine. Surgery was said to be palpative. Have seen great relief of pain in back. Then a month or so later had partial right nephrectomy with clean margins and good kidney output. I am taking Sutent and getting 25 radiation treatments to the spine in S1 & L5 area. I am down 12 of the 25 treatments. Dr. confronted me today with idea of doing 3 additional treatments. His concern is complications that might arise do to previous cobalt treatments 43 years ago. Possible complications are scar tissue in bowel in a few years and nerve damage or scar tissue affecting nerves in and around lower spine. I have a few days to make upmy mind but thought I might find some helpful information here to assist me in making the decision.