A new study found that incidence rates for malignant brain and other central nervous system (CNS) tumors declined by 0.8% annually during 2008 through 2017 in the United States for all ages combined. The decline was driven by trends in adults, whereas rates have slightly increased by 0.5% to 0.7% annually among children and adolescents over the same time period. The report, published by Kimberly D. Miller, MPH, and colleagues in CA: A Cancer Journal for Clinicians, assessed contemporary patterns in brain tumor occurrence in the context of incidence, mortality, and survival trends.
More Findings From the Report
This collaborative study with Central Brain Tumor Registry of the United States researchers, led Dr. Miller, of the American Cancer Society, also found that although malignant brain and other CNS tumors are rare in the United States, they account for a substantial burden of cancer mortality because of their high fatality rate. In 2021, an estimated 83,570 individuals will be diagnosed with brain and other CNS tumors in the United States (24,530 malignant tumors and 59,040 nonmalignant tumors), and 18,000 people will die from the disease.
While incidence rates for malignant tumors are declining overall, survival remains low—only 36% of patients survive more than 5 years after diagnosis, up from 26% for patients diagnosed in the mid-1970s. The slow progress largely reflects a lack of advancement in the early detection and treatment of glioblastoma, for which 5-year survival only increased from 4% to 7% during this time period. Glioblastoma accounts for 49% of all malignant brain cancers in the United States.
Incidence rates for nonmalignant tumors, which disproportionately affect women and Black people, are slowly increasing, likely due to improvements in case finding and increased awareness. For example, incidence rates for meningioma increased by 0.9% annually among adults from 2008 to 2017. Though 5-year relative survival for all nonmalignant tumors remains high (92%), patients often experience debilitating long-term effects from their tumor and/or its treatment.
The report also found persisting disparities among children. For example, mortality rates are the same in White and Black children, despite lower incidence in Black children, reflecting lower 5-year survival (70% vs 79%, respectively). The largest survival disparities between Black and White children diagnosed during 2009 to 2015 were for diffuse astrocytomas (75% vs 86%, respectively) and embryonal tumors (59% vs 67%).
Although the molecular understanding of how brain cancers differ from each other is advancing rapidly, we continue to know little about why these tumors develop in the first place. To facilitate greater understanding, it critical to have access to timely, comprehensive data on occurrence. This is particularly important to understand the causes of sex, age, and racial/ethnic differences, especially for rarer subtypes and among understudied populations.— Kimberly D. Miller, MPH
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“Although the molecular understanding of how brain cancers differ from each other is advancing rapidly, we continue to know little about why these tumors develop in the first place. To facilitate greater understanding, it critical to have access to timely, comprehensive data on occurrence,” said Dr. Miller. “This is particularly important to understand the causes of sex, age, and racial/ethnic differences, especially for rarer subtypes and among understudied populations.”
The report also noted differences in incidence by sex. Malignant brain tumor incidence rates were higher in males (8.3 cases per 100,000) compared to females (6.0 cases per 100,000); conversely, incidence rates for nonmalignant tumors were higher in females (20.3 cases per 100,000) compared to males (12.8 cases per 100,000).
For malignant tumors, sex differences were the most striking among adults aged 45 years or older, among whom rates in females were 30% lower than those in males.
For nonmalignant tumors, sex differences peaked between ages 25 and 29 years, among whom rates in females were more than twofold higher than those in males (10.2 vs 4.7 per 100,000), a pattern driven by high pituitary adenoma rates in females in this age group.
The study authors concluded, “Malignant and nonmalignant brain and other CNS tumors exhibit wide heterogeneity in occurrence by age, sex, and race/ethnicity, and they cause substantial morbidity and mortality in the United States. Because of the aggressive nature of many malignant subtypes and limited knowledge regarding etiology, ongoing updates of the descriptive epidemiology of these tumors is essential. To that end, expansion of resources for central cancer registries to collect and report data in a way that is timely, specific, and broadly consistent across the United States is necessary to advance biologic understanding of brain and other CNS tumors. In addition, ongoing research is needed to elucidate the causes of sex, age, and racial/ethnic differences in occurrence, especially for rarer subtypes and understudied populations. Racial/ethnic disparities in treatment access and receipt should also be further explored.”
Disclosure: For full disclosures of the study authors, visit acsjournals.onlinelibrary.wiley.com.
