Monaz: Hello, I'm Monaz Mehta, editor in the Cochrane Editorial and Methods department. In March 2021, the Cochrane Neuro-Oncology Group published a series of eight new complex systematic reviews on priority topics for the brain tumour community. These were selected from the most important unanswered questions identified by people in this area using James Lind Alliance Priority Setting Partnership methods, which bring together patients and the public with practitioners. One of the reviews was a network meta-analysis of treatments for glioblastoma in the elderly and we asked lead author, Catherine Hanna from the University of Glasgow in the UK, to tell us about the condition and the review.

Catherine: Glioblastoma or GBM is one of the tumours that arises and spreads within a person's central nervous system. It's the most malignant glioma on the WHO glioma classification and invariably has a poor prognosis. It's also the most common brain tumour in adults, with 4 to 6 patients diagnosed with GBM per 100,000 in the UK each year. Approximately half of patients diagnosed with GBM are 65 or over and increasing age is strongly associated with poorer survival. Elderly patients often tolerate treatment less well due to poorer overall fitness, greater neurological deficits, and a higher number of co-existing medical conditions compared to younger patients. It's therefore very important to understand which treatments are effective and tolerated in elderly patients specifically and our review attempts to bring all the relevant evidence together into one place to help with this.
We investigated which treatments have been shown to be effective or cost-effective for elderly patients with GBM, with a focus on those over the age of 70. We found 12 trials that included more than 1800 elderly patients with GBM. Six of the trials recruited elderly patients only, whereas the other six recruited patients of a wider age range. 
Seven trials had sufficient data to be included in a network meta-analysis, in which we combine trials that investigated different treatment comparisons to try to identify are most effective treatments. This analysis showed that chemoradiotherapy prolongs survival compared to radiotherapy and, although less certain, there was some evidence that chemoradiotherapy improves survival compared to temozolomide chemotherapy and that adding bevacizumab to chemoradiotherapy made little or no difference to survival.
Using more the more usual pairwise meta-analyses, we found that chemoradiotherapy prolongs time to progression compared to radiotherapy alone, as does adding bevacizumab to radiotherapy, and that radiotherapy alone probably prolongs disease progression compared to supportive care. There was some evidence that there may be little difference in quality of life between using temozolomide versus radiotherapy alone, but an indication that this chemotherapy did increase clotting and bleeding events compared to radiotherapy. There was also evidence that adding bevacizumab to radiotherapy increased the risk of clotting problems. One trial that we were not able to include in the network meta-analysis suggested that a therapy called tumour treating fields may improve survival when added to chemotherapy after chemoradiotherapy has started, but more research is needed to confirm this for elderly patients.
In summary, our review shows that chemoradiotherapy prolongs survival compared to radiotherapy and may do so compared to chemotherapy alone. If a patient or clinician is deciding between radiotherapy alone or temozolomide alone, they should know that there is probably little difference in quality of life outcomes, and chemotherapy carries a higher risk of bleeding and clotting complications. With regard to bevacizumab, there is no strong evidence to support adding this drug to treatment, and more evidence is needed for the use of tumour treating fields in the elderly.

Monaz: If you would like to learn more about Catherine's network meta-analysis, the trials in the review and its conclusions, you can find it online. Just go to Cochrane Library dot com and search 'glioblastoma in the elderly'.