Proton Therapy With Capecitabine for Rectal Cancer

The primary objective of the Phase I portion of this study is to evaluate the safety of a combination of capecitabine and proton therapy for patients with locally advanced or recurrent rectal cancer. The maximum tolerated dose (MTD) will be determined in the Phase I portion of this trial. The primary objective of the Phase II portion of this study is to evaluate the local control rate in patients treated with the above regimen at the MTD. Secondary Objectives: 1. To evaluate local tumor response in patients treated with the above regimen. 2. To evaluate the relapse-free and overall survival in patients treated with the above regimen. 3. To evaluate proton dosimetry in patients receiving this treatment. 4. To evaluate quality of life in patients receiving this therapy.