Across all adolescent and young adult age groups, tumors most commonly occur in the pituitary gland and craniopharyngeal duct. The largest portion of malignant tumors in those aged 15-39 occurs in the frontal lobe (28.6%). Overall, 50.2% of all malignant tumors in this age group occur in the frontal, temporal, parietal, and occipital lobes. In those aged 15-19 years, tumors most commonly occur in the cerebellum (17%), with 10.4% of tumors originating in the brain stem. Notably, incidences of astrocytomas decrease steadily with age, while meningiomas increase with age. Diffuse astrocytomas (16.1%) and glioblastoma (16%) are the most common glioma histology seen in those aged 15-39 years.
“What’s interesting is the wide variability in the types of brain tumors diagnosed within this age group which paints a much different picture than what we see in adults or in pediatric patients,” study author Jill Barnholtz-Sloan, PhD, of Case Western Reserve University School of Medicine and Scientific Principal Investigator for CBTRUS, said in a statement. “You also clearly see a transition from predominantly non-malignant and low-grade tumors to predominantly high-grade tumors with increasing age,” she said.
Overall, females are more likely to develop primary brain and CNS tumors than males, although this varies when broken down by histology.
Overall 10-year survival rates for malignant brain and CNS tumors have risen from 36.3% in 1973-1977 to 57.6% in 2003-2007; however survival rates for many histologies in this age group have not seen large improvements over time.
Ostrom QT, Gittleman H, De blank PM, et al. American Brain Tumor Association Adolescent and Young Adult Primary Brain and Central Nervous System Tumors Diagnosed in the United States in 2008-2012. Neuro-oncology. 2016;18 Suppl 1:i1-i50.