First line therapies usually induce the longest progression free survival (PFS) in metastatic gastrointestinal cancers (GIC) as compared to subsequent lines of treatment. However, immunotherapy (IT) due to its mechanisms of action could influence sensitivity to conventional cancer therapy (CCT) after progression to IT and thereby, influence both tumor growth rate (TGR) and PFS. We have studied TGR and PFS before and after participation in phase I IT trials.