Prognostic Factors Associated With Survival in Patients With Diffuse Astrocytoma

Background: Diffuse astrocytoma (DA) is a rare disease with inadequately understood epidemiological characteristics and prognosis. Identification of the factors associated with the survival in DA patients is therefore necessary. In this study, we aim to investigate the clinicopathological characteristics of DA to delineate factors influencing the survival of DA. Methods: A population-based cohort study was conducted, utilizing prospectively extracted data from the Surveillance, Epidemiology and End Results (SEER) database. Patients with histological diagnosis of DA in the SEER database from 1973 to 2017 were included. Results: A total of 799 participants with DA were included, consisting of 95.9% fibrillary astrocytoma and 4.1% protoplasmic variants. The average age of participants was 41.9 years, with 57.2% being male. The majority of the population was white (87.5%). More than half (53.9%) of the patients were married. DA arose mostly in the cerebrum (63.8%). Around 71.6% of the population had received surgical treatment. The overall 1-, 3-, 5-, and 10-year survival rate were 73.7, 55.2, 49.4, and 37.6%, respectively. Kaplan-Meier analysis showed that age at diagnosis, marital status, primary tumor site, tumor size, and surgery was possibly associated with cancer-specific survival (CSS) (p < 0.05). Multivariate Cox proportional hazard analysis indicated that surgery was a protective factor whereas older age, larger tumor size, and tumor in the brainstem were harmful factors for patients with DA. Moreover, a nomogram predicting 5- and 10-year survival probability for DA was developed. Conclusions: Age, primary tumor site, tumor size, and surgery were associated with the survival of patients with DA.

Diffusely infiltrating astrocytomas: pathology, molecular mechanisms and markers

Diffusely infiltrating astrocytomas include diffuse astrocytomas WHO grade II and anaplastic astrocytomas WHO grade III and are classified under astrocytic tumours according to the current WHO Classification. Although the patients generally have longer survival as compared to those with glioblastoma, the timing of inevitable malignant progression ultimately determines the prognosis. Recent advances in molecular genetics have uncovered that histopathologically diagnosed astrocytomas may consist of two genetically different groups of tumours. The majority of diffusely infiltrating astrocytomas regardless of WHO grade have concurrent mutations of IDH1 or IDH2, TP53 and ATRX. Among these astrocytomas, no other genetic markers that may distinguish grade II and grade III tumours have been identified. Those astrocytomas without IDH mutation tend to have a distinct genotype and a poor prognosis comparable to that of glioblastomas. On the other hand, diffuse astrocytomas that arise in children do not harbour IDH/TP53 mutations, but instead display mutations of BRAF or structural alterations involving MYB/MYBL1 or FGFR1. A molecular classification may thus help delineate diffusely infiltrating astrocytomas into distinct pathogenic and prognostic groups, which could aid in determining individualised therapeutic strategies.