The only difinitive test for cancer is biopsy. A barium swallow will show contours, defects, etc. but not be a positive test for cancer. The cautious thing to do at this stage would be to set yourself up on a monitoring program at 3 and 6 month intervals. You have had a surgical only solution to a problem. There is always the possiblity that a micro metastasis, too small to be detected in an MRI or CT may be out there. I would watch things, ( not fearfully, but prudently) for the next few years.