Jennifer M. Propp

Temporal trends in incidence of primary brain tumors in the United States, 1985-1999.

A number of reports have indicated an increasing incidence of primary brain tumors over the past few decades. The purpose of this study was to describe incidence rate trends in a population-based series of newly diagnosed primary nonmalignant and malignant brain and other CNS tumors, contributing five additional years to previously published incidence trends. Data for the years 1985 through 1999 from six collaborating state cancer registries of the Central Brain Tumor Registry of the United States were used to determine incidence trends in the broad age groups 0-19, 20-64, and >or=65 years, overall and for selected histologies. Multiplicative Poisson regression was used to express trends as average annual percent change (AAPC). Joinpoint regression was used to identify sharp changes in incidence occurring over this period. Overall, incidence increased modestly (AAPC, 1.1; 95% CI, 0.8-1.4). When brain lymphomas were excluded, this increase remained statistically significant. A sharp change in incidence of brain lymphomas from increasing to decreasing over time was identified. Specific histologies that were increasing included anaplastic astrocytomas in individuals aged >or=65 years, microscopically confirmed gliomas in both adult age groups, and microscopically confirmed glioma, not otherwise specified (NOS), in children. Increases that were not specific to any population subgroup were seen for oligodendrogliomas, ependymomas, meningiomas, and nerve sheath tumors. Decreases were noted for astrocytoma, NOS, nonmicroscopically confirmed gliomas, and pituitary tumors. Improvements in diagnosis and classification are likely reflected in the decreasing trends in unspecified glioma subgroups and the accompanying increasing trends in more specific glioma subgroups. However, increases in meningiomas and nerve sheath tumors deserve further attention.

Descriptive epidemiology of vestibular schwannomas

Vestibular schwannomas, commonly termed acoustic neuromas, arise from the vestibular branch of the eighth cranial nerve (acoustic nerve) and are benign, slow-growing brain tumors that negatively impact patient quality of life. They are thought to account for the majority of intracranial nerve sheath tumors. To describe incidence rate patterns and trends of primary nerve sheath tumors of the brain/CNS and the subset of vestibular schwannomas in two population-based incidence registries, data were obtained from 11 Central Brain Tumor Registry of the United States (CBTRUS) collaborating state registries and the Los Angeles County Cancer Surveillance Program (LACCSP) (1975-1998). Average annual incidence rates were tabulated by age, gender, race, year, and region and were age-adjusted to the year 2000 U.S. standard population. Multiplicative Poisson regression models were used to compare trends in primary nerve sheath tumors of the brain/CNS overall and in subgroups, including vestibular schwannomas, controlling for age, gender, race, microscopic confirmation, and region. Joinpoint regression analysis was used to identify any sharp changes in incidence over time. The overall incidence of primary nerve sheath tumors of the brain/CNS was 1.1 per 100,000 person-years (CBTRUS, 1995-1999 and LACCSP, 1995-1998). The incidence of vestibular schwannomas was similar for both data sets: 0.6 per 100,000 person-years (CBTRUS, 1995-1999) and 0.8 per 100,000 person-years (LACCSP, 1995-1998). Moreover, the incidence of primary nerve sheath tumors of the brain/CNS overall (CBTRUS, 1985-1999 and LACCSP, 1975-1998) and of vestibular schwannomas (CBTRUS, 1992-1999 and LACCSP, 1992-1998) increased over time. However, the incidence of benign schwannomas in sites other than the acoustic nerve either decreased (CBTRUS, 1992-1999) or experienced no significant change (LACCSP, 1992-1998). While improvements in diagnosis and reporting may explain some of these trends, further consideration of potential etiologic factors may be warranted.

Malignant pineal germ-cell tumors: An analysis of cases from three tumor registries

The exact incidence of pineal germ-cell tumors is largely unknown. The tumors are rare, and the number of patients with these tumors, as reported in clinical series, has been limited. The goal of this study was to describe pineal germ-cell tumors in a large number of patients, using data from available brain tumor databases. Three different databases were used: Surveillance, Epidemiology, and End Results (SEER) database (1973-2001); Central Brain Tumor Registry of the United States (CBTRUS; 1997-2001); and National Cancer Data Base (NCDB; 1985-2003). Tumors were identified using the International Classification of Diseases for Oncology, third edition (ICD-O-3), site code C75.3, and categorized according to histology codes 9060-9085. Data were analyzed using SAS/STAT release 8.2, SEER*Stat version 5.2, and SPSS version 13.0 software. A total of 1,467 cases of malignant pineal germ-cell tumors were identified: 1,159 from NCDB, 196 from SEER, and 112 from CBTRUS. All three databases showed a male predominance for pineal germ-cell tumors (>90%), and >72% of patients were Caucasian. The peak number of cases occurred in the 10- to 14-year age group in the CBTRUS data and in the 15- to 19-year age group in the SEER and NCDB data, and declined significantly thereafter. The majority of tumors (73%-86%) were germinomas, and patients with germinomas had the highest survival rate (>79% at 5 years). Most patients were treated with surgical resection and radiation therapy or with radiation therapy alone. The number of patients included in this study exceeds that of any study published to date. The proportions of malignant pineal germ-cell tumors and intracranial germ-cell tumors are in range with previous studies. Survival rates for malignant pineal germ-cell tumors are lower than results from recent treatment trials for intracranial germ-cell tumors, and patients that received radiation therapy in the treatment plan either with surgery or alone survived the longest.

Time trends in oligodendroglial and astrocytic tumor incidence

Background: We hypothesized that the incidences of oligodendrogliomas, anaplastic oligodendrogliomas, and mixed gliomas have significantly increased from the early 1990s forward, while the incidences of anaplastic and grade II astrocytic tumors have significantly decreased. Methods: Data for the years 1973–2004 from the Surveillance, Epidemiology and End Results (SEER) public-use data and for 1985–2004 from six collaborating registries of the Central Brain Tumor Registry of the US (CBTRUS) were obtained. SEER*Stat was used to estimate age-adjusted incidence trends and annual percent change (APC) for selected histologies. Joinpoint regression was used to identify sharp changes in incidences occurring over time. Results: Using CBTRUS data, the incidences (per 100,000 person-years) of oligodendrogliomas (APC = 4.7), mixed gliomas (APC = 3.9) and anaplastic oligodendrogliomas (APC = 12.5) have all increased over time, while the incidences of astrocytoma not otherwise specified (APC = –8.1) and fibrillary astrocytoma (APC = –2.1) have decreased. Restricting the analyses to later years (1992–2004) using SEER data shows the incidence of oligodendrogliomas leveling off (APC = 0.5), while joinpoint analyses demonstrate a decreasing trend after 1998. Conclusions: This study has demonstrated that increases in oligodendroglial tumor incidence correspond to decreases in astrocytic tumor incidence over the same time period. Minimizing misclassification of glial tumors will be essential for accurately assessing incidence, survival, and mortality rates, as well as for identifying homogeneous subgroups for epidemiologic and treatment studies.

Gender affects survival for medulloblastoma only in older children and adults: A study from the surveillance epidemiology and end results registry

Males have a higher incidence of medulloblastoma (MB) than females, but the effect of gender on survival is unclear. Studies have yielded conflicting results, possibly due to small sample sizes or differences in how researchers defined MB. We aimed to determine the effect of gender on survival in MB using a large data set and strict criteria for defining MB.

Descriptive epidemiology of central nervous system germ cell tumors: nonpineal analysis

Central nervous system (CNS) germ cell tumors (GCT) have not been epidemiologically well described. Our study describes 2 population-based series of nonpineal CNS GCT. Data on all primary (malignant and nonmalignant) CNS (ICD-O-3 sites: C70.0-C72.9, C75.1-C75.3) GCT diagnosed between 2000 and 2004 from the Central Brain Tumor Registry of the United States (CBTRUS) and on all malignant GCT diagnosed between 1992 and 2005 from the Surveillance, Epidemiology, and End Results (SEER) were analyzed. Of 234 nonpineal GCT in CBTRUS, the most common site was brain, NOS (31.6%). Males had a greater frequency (59.7%) than females (40.3%). However, by age group, the male-to-female incidence rate ratio (IRR) differed: children (0-14 years) had an IRR of 1.1, young adults (15-29 years) an IRR of 2.3, and adults (aged 30+) an IRR of 1.0. For children and young adults, most tumors were malignant (86.8% and 89.0%, respectively), whereas for adults, more than half were nonmalignant (56.8%). Germinoma was the most frequent diagnosis (61.5%). In SEER, the frequency of malignant GCT in the CNS (2.5%) was greater than that in the mediastinum (2.1%). Of 408 malignant CNS GCT, 216 (52.9%) were nonpineal. The male-to-female IRR was 1.5. Overall relative survival for nonpineal CNS malignant GCT was 85.3% at 2 years, 77.3% at 5 years, and 67.6% at 10 years. Previous studies of GCT that have not stratified by site have suggested greater gender disparity. Nonpineal CNS GCT show no significant gender preference, yet have outcomes similar to pineal GCT.

Medulloblastoma incidence has not changed over time: a CBTRUS study.

Earlier studies have reported changes in the incidence of medulloblastoma (MB) but have conflicted, likely because of small sample size or misclassification of MB with primitive neuroectodermal tumor (PNET). The incidence of MB and PNET from 1985 to 2002 was determined from the Central Brain Tumor Registry of the United States, a large population-based cancer registry, using strict histologic and site codes. No statistically significant change in MB incidence was observed over the last 2 decades, but there was an increase in MB and PNET combined.

Average years of potential life lost in those who have died from brain and CNS tumors in the USA.

The aim of this study was to quantify the impact of all primary malignant and nonmalignant brain and central nervous system (CNS) tumors on mortality in the USA in terms of years of life lost, an indicator of premature mortality in the population. In this study, US mortality data for the year 2001 from the National Center for Health Statistics and life tables from the US Census Bureau were used. Person-years of potential life lost (PYPLL) and average years of potential life lost (AYPLL) were calculated for all deaths due to brain and CNS tumors as an underlying cause. 16,819 deaths due to brain and CNS tumors occurred in 2001, leading to a total loss of 357,483 person-years of life and an average loss of 21.3 years (AYPLL). Hispanic men and women had an AYPLL of 31.7 and 33.9 years, respectively, a figure substantially higher than other race and ethnicity categories. Malignant tumors led to an AYPLL of 25 years, which was significantly higher than the AYPLL of 19 years due to nonmalignant tumors. The relative impact of tumors arising in the various anatomical sites in the brain and CNS among adults and among children was not similar. The use of population survival indicators, such as PYPLL and AYPLL, will help better understanding of the effect of racial, ethnic, gender and age differences on the mortality due to malignant and nonmalignant brain and CNS tumors. Information on years of life lost, as well as mortality data, will be useful in focusing research priorities and resources in this field.

A Case for the Worldwide Collection of Primary Benign Brain Tumors

Background: Incidence data on malignant tumors are reported by the International Agency for Research on Cancer, with 189,485 new malignant brain tumors globally in 2002. However, collection and reporting of benign brain tumors are not universal. The objective here is to encourage the collection of primary benign brain tumors worldwide. Methods: Worldwide numbers of primary benign brain tumors were estimated through published articles and cancer registry reports presenting directly or indirectly reported benign incidence rates or frequencies for regions or countries. Results: An estimated 186,678 benign brain tumors were diagnosed worldwide in 2002. The estimated numbers of benign brain tumors were higher in females than males (105,918 vs. 80,759). Since many countries do not report primary benign brain tumors, the incidence rate estimates vary significantly by region. Conclusions: This is the first survey to assess worldwide numbers of benign brain tumors. Under-reporting, non-standardized collection, lack of age-adjustment, and other causes of the varying incidence rates must be considered. However, the estimated number of benign brain tumors approximately equals, and could exceed, the number of malignant brain tumors globally. Registration of primary benign brain histologies in different geographical areas and ethnicities could provide clues to the underlying causes of these tumors.