Continuation of adjuvant temozolomide until tumor progression after upfront chemoradiation therapy produces promising survival in patients with GBM, especially with pseudoprogression.

e13001 Background: Radiation therapy with concomitant temozolomide (TMZ) followed by 6 months of adjuvant TMZ is standard of care in newly diagnosed glioblastoma multiforme (GBM). The 6-month time frame for adjuvant TMZ was chosen arbitrarily and the optimal duration of TMZ chemotherapy remains undefined. In addition, the duration of TMZ chemotherapy and survival can be affected by uncertainty in differentiating pseudoprogression (Ps), indicating necrosis/inflammation, from true tumor progression. This IRB-approved retrospective study determined the survival of GBM patients treated with chemoradiotherapy (CRT) and adjuvant TMZ continued until tumor progression. Methods: Patients with biopsy-proven newly diagnosed GBM at Oregon Health and Science University from January 2006 to June 2012 were treated with upfront CRT followed by adjuvant TMZ without Pneumocystis jirovecii pneumonia prophylaxis until tumor progression. Diagnosis of Ps was made by relative cerebral blood volume (rCBV) estimation based on per...