You will be assigned to a dose level of capecitabine based on when you joined this study. Up to 4 dose levels of capecitabine will be tested. Up to 6 participants will be enrolled at each dose level. The first group of participants will receive the lowest dose level. Each new group will receive a higher dose than the group before it, if no intolerable side effects were seen. This will continue until the highest tolerable dose of capecitabine is found.