Annual Report to the Nation on the Status of Cancer, 1975-2007, Featuring Trends in Brain Cancer: Questions and Answers
- Overall cancer death rates have continued to decrease since the early 1990s among both men and women. Death rates decreased on average 1.6 percent per year between 2003 and 2007. (Question 8)
- Incidence rates for all cancers combined decreased 0.8 percent per year from 2003 through 2007 for both sexes. (Question 5)
- Incidence rates of brain tumors differ by race/ethnicity, with whites at highest risk. (Question 12)
What is the purpose of this report and who created it?
This report provides a regular update of cancer incidence (new cases) and mortality rates (deaths) and trends in these rates in the United States, as well as an in-depth analysis of brain and other nervous system cancer trends. The North American Association of Central Cancer Registries (NAACCR), the National Cancer Institute (NCI), which is part of the National Institutes of Health, the American Cancer Society (ACS), and the Centers for Disease Control and Prevention, have collaborated since 1998 to create this report.
The feature section of this report highlights benign and malignant brain and nervous system tumors with an emphasis on cases diagnosed in 2004 and later, following passage of the Benign Brain Tumor Cancer Registries Act.
What are the sources of the data?
Cancer mortality information in the United States is based on causes of death reported by physicians on death certificates and filed by state vital statistics offices. The mortality information is processed and consolidated in a national database by the CDC through the National Vital Statistics System, which covers the entire United States.
Information on newly diagnosed cancer cases occurring in the U.S. is based on data collected by registries in the CDC's National Program of Cancer Registries (NPCR) and NCI's Surveillance, Epidemiology, and End Results (SEER) Program. NAACCR evaluates and publishes data annually from registries in both programs.
Long-term (1992 through 2007) trends for all races for all cancer sites combined and for the 15 most common cancers were based on SEER incidence data covering about 14 percent of the U.S. population. Data from NAACCR covering 40 population-based cancer registries were used to assess short-term trends from1998 through 2007. Data from 46 NAACCR population-based cancer registries were used to estimate a five-year period from 2003 through 2007 for each of the five major racial/ethnic populations: white, black, Asian and Pacific Islander, American Indian/Alaska Native, and Hispanic. The 40 and 46 registries met NAACCR's data quality criteria for each year included in the analysis. The registries covered 83.6 percent and 93.0 percent of the U.S. population, respectively.
Which reporting periods were chosen as a main focus of the report?
The period from 2003 through 2007 was used for describing the U.S. burden of cancer, and the period from 1998 through 2007 was used for describing trends in cancer incidence and death among the country's five major racial and ethnic populations. The period from 1975 through 2007 was chosen to represent the best perspective on long-term trends in cancer death rates among all races combined, while the period from 1992 through 2007 was chosen to represent the best perspective on long-term incidence trends.
What is detailed in the Special Feature of this year's report?
In this year's Special Feature, the authors explore unique challenges with respect to the diversity of brain and nervous system cancers. Significantly, this report examines brain tumors beyond those that are identified as malignant and looks at those that are borderline and benign, from 2004 through 2007.
Update on Incidence and Mortality Trends for All Cancer Sites Combined and the Top 15 Cancers
What is happening with cancer incidence trends overall?
Overall, cancer incidence rates for all racial and ethnic groups and both sexes combined decreased by 0.8 percent each year from 2003 through 2007, with a 0.6 percent annual decline for women and a non-statistically significant decline for men that was influenced by the recent 2005 through 2007 non-statistically significant increase in prostate cancer incidence [See Table 1 of manuscript]. When prostate cancer was excluded from the trend analysis, there was a statistically significant decline in incidence for all sites combined in men and women.
In contrast with mortality, for which declines are always good news, declines in incidence may reflect good news (decreases in risk factors that cause cancer or increased use of screening tests, such as colorectal and cervical cancer tests, that can actually help prevent cancer by allowing the removal of precancerous growths), bad news (decreased use of screening tests) or a combination of the two.
What is happening with long-term incidence trends for the top 15 cancers?
Among men, incidence rates of melanoma, and cancers of the liver, kidney, and pancreas increased in the five-year period from 2003 through 2007. Incidence rates decreased for lung, oral cavity, brain, stomach, and colorectal cancers. Rates were stable for cancers of the bladder, and esophagus, as well as for non-Hodgkin lymphoma, myeloma, and leukemia. Prostate cancer incidence rates were stable with a non-statistically significant increase of 3.0 percent per year during the period from 2005 through 2007.
Among women, incidence rates of melanoma, and cancers of the kidney, thyroid, leukemia, and pancreas increased during the period from 2003 through 2007. Incidence rates decreased for cancers of the breast, lung, colorectum, uterus, cervix, bladder and oral cavity. Rates were stable for ovary and brain/nervous system cancers.
What is happening with incidence trends for breast cancer?
Breast cancer incidence rates, which increased 1.1 percent per year from 1992 through 1999, declined an average of 1.8 percent per year from 1999 through 2007. When examining incidence data for each year, the authors note that the decline in incidence does not continue after 2003. The factors that influence breast cancer incidence are complex, including changes in reproductive risk, obesity, the prevalence of mammography screening, and others. Recent reports suggest that the decrease in breast cancer incidence may be related to the rapid discontinuation of hormone replacement therapy, a known risk factor for breast cancer, as well as to a decline in mammography screening prevalence. A paper published Feb. 28, 2011, in Cancer Epidemiology, Biomarkers and Prevention (CEBP), examined trends in breast cancer incidence from 2000 through 2007. The research showed a decrease in breast cancer incidence rates from 2002 through 2003, but that this decline abated after 2003.
What is happening with cancer mortality trends overall?
Based on long-term mortality trends, overall cancer death rates have continued to decrease since the early 1990s among both men and women and decreased an average 1.6 percent per year between 2003 and 2007. For 2003 through2007, this decline was slightly more pronounced among men (1.9 percent per year) than women (1.5 percent per year). For children up to age 20, cancer death rates have declined since the 1970s. Death rates are the best indicator of progress against cancer.
What is happening with death rates for the top 15 cancers among men and women?
Among men, death rates decreased for 10 of the top 15 sites for both a five-year and 10-year period, including lung, prostate, colorectal, kidney, stomach, brain (malignant), and oral cavity cancers, as well as non-Hodgkin lymphoma, myeloma, and leukemia. Although colorectal cancer death rates declined for more than two decades, the most recent decline, from 2005 through 2007, was not statistically significant. Death rates for cancer of the liver and melanoma have increased, and an upturn in deaths due to cancer of the pancreas was reported during the most recent five-year time period.
Among women, death rates decreased for 11 of the top 15 cancers, including breast, ovary, and bladder, colorectal, brain (malignant), stomach, and kidney, as well as non-Hodgkin lymphoma, leukemia, and myeloma. Lung cancer death rates decreased in the recent five-year period, from 2003 through 2007, following long-term increases during the period from 1975 through 2003. In contrast, after decreasing from 1975 through 1997, the death rates for uterine cancer increased from 1997 through 2007. The pattern for ovarian cancer mortality has been inconsistent over time; however, rates decreased between 2003 and 2007. After many years of decreasing, cervical cancer death rates for the most recent five-year period do not show a statistically significant decrease. Death rates for pancreatic and liver cancer have increased since at least the late 1970s in women.
If cancer death rates continue to fall, does that mean the number of people dying from cancer will also continue to fall?
Not necessarily. The data described in the report are rates (number of deaths per 100,000 persons in the United States) and are adjusted for age, so they are comparable across various factors, such as race, time, and region. The actual number of people dying from cancer (sometimes called the count) can be influenced by several factors, including the growth in the number of older people in the United States (cancer is primarily a disease of aging) and the increase in size of the population.
Therefore, while the cancer death rate may go down in a given year, if there is an increase in the size and the overall age of the U.S. population that same year, the actual count of the number of cancer deaths could go up.
What is happening with childhood cancer rates?
Among children through the age of 19, cancer incidence rates have increased by 0.6 percent each year for both the most recent five-year period, 2003 through 2007, as well as the entire period from 1992 through 2007. Death rates continue to decrease, although the rate of decline has slowed since the mid-1990s; death rates declined 2.7 percent per year between 1975 and 1996 and declined 1.2 percent per year between 1996 and 2007. Considerable progress has been seen for many types of cancers that occur in children, resulting in overall declines in death rates for cancer among children since at least 1975.
When looking specifically at brain tumors, among children through age 19, the percentage of tumors that were malignant was higher than in adults. Malignant brain tumors in children were seen in 65.2 percent of brain tumor diagnoses, as compared to 33.7 percent in adults. Death rates for malignant brain tumors from 1999 through 2007 were stable in children. Mortality rates for benign brain tumors declined significantly (2.5 percent each year) in children through age 19.
Trends in brain tumors
What is happening with incidence rates for brain tumors?
Overall, from 2004 through 2007, 35.8 percent of the primary brain and other nervous system (ONS) tumors diagnosed were malignant, making non-malignant tumors about twice as common as malignant tumors in people over age 19. Incidence rates of neuroepithelial brain tumors among men and women rose 2.0 percent each year from 1980 through1987, and declined 0.4 percent each year from 1987 through 2007.
How do brain cancer incidence rates differ by race/ethnicity?
Whites had the highest incidence rates of brain tumors (malignant and non-malignant combined) at 19.0 per 100,000, followed by Hispanics at 17.8 per 100,000, and blacks at 17.7 per 100,000. American Indian/Alaska Natives had lower incidence rates of brain and other nervous system tumors at 15.3 per 100,000, and Asian and Pacific Islanders had the lowest rates at 13.5 per 100,000.
Glioblastoma was the most common type of neuroepithelial brain cancer, with whites having the highest incidence rates, followed by Hispanics, blacks, and American Indian/Alaska Natives. Asian and Pacific Islanders had roughly one-half the rate of these tumors when compared to whites.
How do brain tumor incidence rates differ among men, women and children?
Brain tumors are much more common among adults than among children. However, if a child is diagnosed with a brain tumor, it is more likely to be malignant. Adults are more likely to be diagnosed with a non-malignant tumor. Malignant brain tumors were seen in 65.2 percent of brain tumor diagnoses in children, as compared to 33.7 percent in adults.
Incidence rates for tumors of neuroepithelial tissue, a common type of brain tumor that is malignant in 94.9 percent of cases, were highest among men. Glioblastoma, a subtype of neuroepithelial tissue tumors, occurred 1.6 times more often in men than in women.
Meningioma, a non-malignant brain tumor, was the most frequently diagnosed type of brain tumor. Meningiomas were diagnosed over twice as often in women when compared to men and more often in blacks than whites.
What is happening with death rates for brain tumors?
Death rates for malignant brain tumors were stable from 1999 through 2007 in children (up to age 19) but declined significantly in adults (over age 20) at a rate of 1.2 percent each year. Death rates for benign brain tumors declined significantly in adults by 2.3 percent each year and by 2.5 percent each year in children (up to age 10).
For brain tumors, what affects survival rates and what are the late effects of therapy for children?
Modest improvements in survival rates for many types of brain tumors likely result from improvements in diagnostic and surgical techniques, radiotherapy, chemotherapy, biological therapy and the use of multimodality therapy. Major prognostic factors include the microscopic cellular makeup of the tumor, whether complete surgical removal is achieved, and the age of the patient at diagnosis. Late effects of therapy for childhood brain tumors are significant and include neurocognitive deficiencies, hormone deficits, growth impairment, second primary brain tumors, and toxicity related to a form of chemotherapy that uses the element platinum as a central component.
What are the primary risk factors for brain tumors and how can they be modified?
Several reviews of risk factors for brain tumors have been published recently. The relatively low variation in incidence and mortality rates for cancer of the brain and nervous system, nationally and internationally, suggests that environmental risk factors do not play a major role in this disease. In fact, other than hereditary tumor syndromes and increased familial risk without a known syndrome, the only known modifiable risk factor related to causation for brain tumors is exposure to ionizing radiation. Variability in age at onset, and in molecular tumor characteristics, suggests that risk factors for brain tumors may differ by the particular type of tumor. An example is the mostly consistent inverse association that has been observed between history of atopic disease (allergy hypersensitivity), including allergies and asthma, and risk of glioma and possibly meningioma; but no association with nerve sheath tumors (those that involve the casing along nerves) has been found. However, further research is needed to understand the complex interactions involved.
Where can I find out more about brain tumors?
More information can be found by going to the website of Central Brain Tumor Registry of the United States at http://www.cbtrus.org.
How to Read This Report
How are cancer incidence and death rates presented?
Cancer incidence rates and death rates are typically measured as the number of cases or deaths per 100,000 people per year and are age-adjusted to the 2000 U.S. standard population. When a cancer affects only one sex—for example, prostate cancer—then the number is per 100,000 persons of that sex. The numbers are age-adjusted, which allows for comparison of rates from different populations with varying age composition over time and in different regions. It is noteworthy that breast cancer occurs in both men and women, although it occurs less frequently in men. For rarer cancers, such as some that occur in children, rates can be represented per one million people.
What is annual percent change or APC?
The annual percent change (APC) is the average rate of change in a cancer rate per year in a given time frame (i.e., how fast or slowly a cancer rate has increased or decreased each year over a period of years). The APC was calculated for both incidence and death rates. The number is given as a percent, such as an approximate 1 percent per year decrease.
A negative APC describes a decreasing trend, and a positive APC describes an increasing trend. In this report, all trends are statistically significant unless noted otherwise.
What is average annual percent change or AAPC?
This year's report uses the average annual percent change (AAPC) as an addendum to the underlying joinpoint (see below for an explanation of jointpoints) annual percent change (APC) trends as a summary measure to compare fixed interval trends by race/ethnicity. The AAPC quantifies the average trend over a fixed period of multiple years. In describing long-term and short-term trends with APC and AAPC estimates, all trends described as "increasing" or "decreasing" are statistically significant unless otherwise noted. Non-statistically significant trends may be described as "level," "stable," "non-significant decrease" or "non-significant increase."
Based on long-term trends, the AAPCs for the most recent five years, 2003 through 2007, were similar to the APCs for the most recent time period. As expected, when the incidence trend fluctuated over time, the 10-year (1998-2007) AAPCs differed from the most recent APCs, e.g., all sites combined for men and women, and cancers of the prostate and pancreas in men, and cancers of the breast, pancreas, and ovary, in women.
Similar to incidence trends, the AAPCs in death rates for 2003 through 2007 were generally similar to the APCs for the most recent joinpoint period. However, long-term trends can often obscure shorter term changes. Differences in the five-year and 10-year AAPCs typically identify types of cancer where the 10-year trend may mask important recent changes.
Why were rates adjusted for delays in reporting incidence data to SEER?
The report presents analyses of long-term trends in cancer incidence rates with and without adjustment for reporting delays and more complete information. Adjusting for these delays and accumulating more complete and accurate information provides the basis for a potentially more definitive assessment of incidence rates and trends in the most recent years for which data are available. Cancer registries routinely take two to three years to compile their current cancer statistics. An additional one to two years may be required to have more complete incidence data on certain cancers, such as melanomas and leukemias, particularly when they are diagnosed in outpatient settings. Cancer registries continue to update incidence rates to include these cases. Consequently, the initial data reported for certain cancer incidence rates may be an underestimate. Long-term reporting patterns in SEER registries have been analyzed, and it is now possible to adjust site-specific incidence rates and incidence rates for all cancers combined to correct for expected reporting delays and more complete information.
What is joinpoint analysis and how does it account for the different time periods used for trends analysis in this report?
Joinpoint analysis is a statistical method that describes changing trends over successive segments of time and the amount of increase or decrease within each segment. This statistical method chooses the best-fitting point or points, which are called joinpoints; these points are where the rate of increase or decrease changes significantly.
Joinpoint regression analysis involves fitting a series of joined straight lines to the age-adjusted rates, and each line segment is described by an annual percent change that is based on the slope of the line segment. Each joinpoint denotes a statistically significant change in trend. Joinpoint analyses were performed for incidence and mortality trends.
What other data issues need to be considered?
This report uses data from the U.S. Census Bureau to calculate incidence and death rates. National and state population estimates for 2003 through 2007 are based on new, improved methodology, which affected some state-level incidence rates for 2007.
Incidence data for 2005 through 2007 were affected by data sharing restrictions within the Veterans Health Administration (VHA). VHA hospitals have traditionally been a critical source of data for cancer cases diagnosed among veterans served by those institutions. The new requirements restrict the submission of cancer cases to central cancer registries, however, resulting in incomplete reporting of VA hospital cases in some registries. VA cases account for at least 3 percent and possibly as much as 8 percent of all cancer cases diagnosed among men. Therefore, incidence rates for men may be underestimated. Since late 2008, VA facilities and states with central cancer registries have worked to establish data transfer agreements that may help cancer registries receive missing VA cases over time and provide a more complete estimate of national cancer incidence.
Where is this report published?
To view the full report in the Journal of the National Cancer Institute, please go to http://www.oxfordjournals.org/our_journals/jnci/press_releases/kohlerdjr077.pdf.
Reference: Kohler BA, Ward E, McCarthy BJ, Schymura MJ, Ries LAG, Eheman C, Jemal A, Anderson RA, Ajani UA, Edwards BK. Report to the Nation on the Status of Cancer, 1975-2007, Featuring Tumors of the Brain and Other Nervous System.JNCI; Published online March 31, 2011, and in print on May 4, 2011.
Where can I find out more about the report?
For a press release on this Report, go to http://www.cancer.gov/newscenter/pressreleases/2011/ReportNation2011release
For Spanish translations of this press release and Q&A, go to http://www.cancer.gov/espanol/noticias/ReportNation2011SpanishRelease
Central Brain Tumor Registry of the United States: http://www.cbtrus.org
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