Introduction: With the 2016 update of the WHO Classification of Tumors of the Central Nervous System incorporating molecular subtyping to histology, WHO grade II diffuse astrocytic and oligodendroglial tumors are now subcategorized by distinct molecular markers. Currently, there are no published systematic reviews quantifying differences in progression free survival (PFS) and overall survival (OS) on the basis of molecular subtypes of WHO grade II diffuse gliomas, against the background of administered treatments.
Methods: Utilizing the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) and the Cochrane Handbook of Systemic Reviews of Interventions, we conducted a systematic review through MEDLINE, Embase, and CENTRAL.
Results: For OS, the first quartile (25%), median (50%), third quartile (75%), and 95% confidence interval were respectively identified (in months)—astrocytoma-wild type WHO II (A-wt II): 22.8, 32.2, 40.7, and 21.6-61.2; astrocytoma-mutant WHO II (A-mt II): 69.85, 115.2, 128.4, and 55.4-164.0; oligodendroglioma WHO II (OD II): 106.3, 163.7, 213.3, and 67.3-235.4 (p-value = 0.0001675). For PFS, the 25th, 50th, and 75th percentiles, and 95% confidence interval are as follows (in months), respectively—A-wt II: 6.90, 17.45, 19.57, and 3.00-23.69; A-mt II: 37.20, 43.20, 55.63, and 35.7-60.0; OD II: 47.42, 59.2, 88.28, and 46.3-91.2 (p-value = 0.01488).
Conclusions: This appears to be the first systematic review of OS and PFS in patients with WHO grade II LGGs, against treatment modalities, in molecularly stratified subsets introduced by the WHO 2016 classification of CNS tumors. Overall, A-wt II was confirmed to have a significantly shorter OS than A-mt II; meanwhile, there was no significant difference found between OS of OD II with A-wt II and A-mt II. Additionally, all three molecular subtypes were found to have statistically significant differences between PFS, with OD II having a statistically better PFS than A-mt II. These data can provide valuable prognostic insight to patients and clinicians. Additionally, assessing survival differences enhances understanding of treatment recommendations against molecular markers and may facilitate future clinical trial design.
Patient Care: Knowing the raw PFS or OS data helps design better future clinical trials and provides patients with more tangible information when making critical and complex treatment decisions. Additionally, despite the limitations, this study makes sense of the best available data, helping better elucidate the progression and outcomes of WHO grade II gliomas.
Learning Objectives: • Median progression free survival and overall survival for grade II wild type astrocytomas was found to be 17.45 and 32.2 months, respectively.
• Median progression free survival and overall survival for grade II mutant astrocytomas was found to be 43.20 and 115.2 months, respectively.
• Median progression free survival and overall survival for grade II oligodendrogliomas was found to be 59.20 and 163.7 months, respectively.
• Grade II wild type astrocytoma overall survival was found to be significantly shorter than grade II mutant astrocytomas, but no significant differences were found between overall survival of grade II oligodendrogliomas and mutant or wild type astrocytomas.
• All three molecular subtypes of grade II gliomas had significantly different progression free survivals.