common use. Chemotherapy Most studies show no benefit from the addition of chemotherapy. However, a large clinical trial of 575 participants randomized to standard radiation versus radiation plus temozolomide chemotherapy showed that the group receiving temozolomide survived a median of 14.6 months as opposed to 12.1 months for the group receiving radiation alone. This treatment regimen is now standard for most cases of glioblastoma where the person is not enrolled in a clinical trial. Temozolomide seems to work by sensitizing the tumor cells to radiation, and appears more effective for tumors with MGMT promoter methylation. High doses of temozolomide in high-grade gliomas yield low toxicity, but the results are comparable to the standard doses. Antiangiogenic therapy with medications such as bevacizumab control symptoms, but do not appear to affect overall survival in those with glioblastoma. The overall benefit of anti-angiogenic therapies as of 2019 is unclear. In elderly people with newly diagnosed glioblastoma who are reasonably fit, concurrent and adjuvant chemoradiotherapy gives the best overall survival but is associated with a greater risk of haematological adverse events than radiotherapy alone. Other procedures Alternating electric field therapy is an FDA-approved therapy for newly diagnosed and recurrent glioblastoma. In 2015, initial results from a phase-III randomized clinical trial of alternating electric field therapy plus temozolomide in newly diagnosed glioblastoma reported a three-month improvement in progression-free survival, and a five-month improvement in overall survival compared to temozolomide therapy alone, representing the first large trial in a decade to show a survival improvement in this setting. Despite these results, the efficacy of this approach remains controversial among medical experts. However, increasing understanding of the mechanistic basis through which alternating electric field therapy exerts anti-cancer effects and results from ongoing phase-III clinical trials in extracranial cancers may help facilitate increased clinical acceptance to treat glioblastoma in the future. A Tel Aviv University study showed that pharmacological and molecular inhibition of the P-selectin protein leads to reduced tumor growth and increased survival in mouse models of glioblastoma. The results of this research could open to possible therapies with drugs that inhibit this protein, such as crizanlizumab. Prognosis The most common length of survival following diagnosis is 10 to 13 months, with fewer than 1–3% of people surviving longer than five years. In the United States between 2012 and 2016 five-year survival was 6.8%. Without treatment, survival is typically 3 months. Complete cures are extremely rare, but