CHEMORADIOTHERAPY FOR BRAIN TUMORS

Among malignant brain tumors, glioblastoma is the most common. This is an exceptionally aggressive and locally spreading tumor with a very poor prognosis and low survival rate. Glioma is considered resistant to chemotherapy and radiation. Recently, concomitant and adjuvant chemoradiotherapy with temozolomide has become the standard treatment method for newly diagnosed glioblastoma. Other chemotherapy regimens in neoadjuvant or adjuvant regimens with procarbazine, lomustine and vincristine failed to improve survival rates. Preclinical studies suggest synergism or additivity of radiation therapy and temozolomide in glioma cell lines. Epigenetic inactivation of the DNA repair enzyme methylguanine methyltransferase (MGMT) appears to be the strongest prognostic marker of outcome in patients treated with chemotherapy with alkylating agents. Patients whose tumors lack methylation of the MGMT promoter are less likely to benefit from the addition of temozolomide chemotherapy and need alternative treatment strategies, such as a targeted approach using vatalanib tyrosine kinase, vandetinib, cilengitide integrin inhibitor, bevacizumab and cetuximab monoclonal antibodies.