Oral Capecitabine and Temozolomide (CAPTEM) for Newly Diagnosed GBM

The purpose of this study is to evaluate the safety and efficacy of administering the medication capecitabine along with temozolomide when you start your monthly regimen of oral temozolomide for the treatment of your newly diagnosed glioblastoma multiforme (GBM). Capecitabine is an oral chemotherapy that is given to patients with other types of cancer. The study will evaluate whether the dosage of 1500 mg/m2 of capecitabine is tolerable after radiation, when taken along with temozolomide. It will also try to determine if the medication capecitabine helps patients respond to treatment for a longer period of time compared to just temozolomide alone, which is the standard of care.