Capecitabine and Lenvatinib With External Radiation in Rectal Adenocarcinoma

Pre-surgery Lenvatinib, days 1 - 5. Dose Escalation Levels: 1.) 10 mg by mouth (PO) daily (QD); 2.) 14 mg PO QD; 3.) 20 mg PO QD; 4.) 24 PO QD.

Pre-surgery Capecitabine, 850 mg/m\^2, twice a day (BID) on days 1-5 for 5½ -6 weeks.

Pre-surgery RT: Participants will receive 6 weeks of radiation therapy. The radiation sessions will be daily, Monday through Friday, except for holidays.