Abscopal Effect for Metastatic Colorectal Cancer

Patients with colorectal cancer that had metastatic lesions after been treated with definitive surgery or chemoradiotherapy are being asked to participate in this study. 1. To observe immunity-mediated tumor response outside the radiation field (abscopal effect) after chemoradiotherapy of a metastatic site in metastatic colorectal cancer patients. 2. To induce the efficacy (effectiveness) of a new combination of therapy, chemoradiotherapy and thymalfasin for heavily pretreated, metastatic esophageal cancer patients; 3. To explore the role of PET/CT scanning to assess tumor response/abscopal effect. This study will help find out what abscopal effects (good or bad) the combination of radiotherapy and thymalfasin has on metastatic esophageal cancer.