Impact of radiation fractionation on pseudoprogression in older patients with glioblastoma: a retrospective cohort study.

AIMS: We aimed to investigate a potential association between hypofractionated radiotherapy (HFRT) vs. conventional radiotherapy (CRT) and development of pseudoprogression in patients over the age of 65 treated for glioblastoma (GBM). MATERIALS & METHODS: Seventy-nine patients with glioblastoma (29 who received HFRT and 50 who received CRT) were included in this retrospective cohort study from a single institution. Demographic, clinical, and radiation information, including development of pseudoprogression and standard prognostic factors like Karnofsky Performance Status (KPS) and extent of surgical resection, were collected. RESULTS: Radiation regimen alone was not associated with development of pseudoprogression. Patients who had lower KPS at the time of diagnosis and received HFRT had lower rates of pseudoprogression. There was no association between radiation regimen, pseudoprogression, and any other clinical factors. CONCLUSION: Older patients with glioblastoma who receive HFRT are not more likely to develop pseudoprogression than those who receive CRT. Patients with lower functional status receiving HFRT may be less likely to mount an inflammatory response leading to pseudoprogression. Prospective investigation is warranted to validate these results and evaluate other factors leading to treatment complications in older patients with glioblastoma in order to optimize outcomes and minimize toxicity.