Patient demographic data will be collected at baseline. Once patients start chemotherapy, treatment toxicity data will be collected prior to chemotherapy and after cycles 1-3. For patients receiving continuous chemotherapy such as infusional 5-FU or capecitabine concurrent with radiation, a cycle will be defined as 2 weeks. Toxicity data will be collected following Common Terminology Criteria for Adverse Events (CTCAE) v4.0. Data will be collected for common side effects associated with typical colorectal cancer chemotherapy regimens including, leukopenia, neutropenia, anemia, thrombocytopenia, fatigue, nausea/vomiting, diarrhea, mucositis, hand-foot syndrome, peripheral neuropathy, and abdominal pain. Other toxicities identified by study staff will be collected as well. Chemotherapy dose modifications made by the treating physician will be collected for chemotherapy cycles 1-3.