How well cancer of the esophagus responds to chemoradiation varies from person to person. Currently, doctors cannot tell before surgery in which patients the chemoradiation will kill all of the cancer, some of the cancer, or not much of the cancer. Studying patients' PET/CT scans and tumor tissue for biomarkers may help researchers predict how an individual patient will respond to chemoradiation. This could spare future patients from having unnecessary surgery or chemoradiation treatment that is not effective.