Taking drugs by mouth, rather than by injection, is the obvious way to get them directly to the source of problem when the malignant tissue is located within the intestinal tract (such as in cancer of the colon).
had a friend with a tumour near the base of the spine, this was treated with chemo in pill form, it had to be taken in the hospital though. At the same time my wife was going through breast cancer and the chemo was the usual intravenus (not quite sure thats the right spelling)...