Annual Report to the Nation on the Status of Cancer, 1975 -2011: Questions and Answers
What is the purpose of this report and who created it?
This report provides a yearly update of cancer incidence (new cases) and mortality (death) rates, and trends in these rates in the United States. The special feature section of this year’s report highlights the incidence of breast cancer subtypes by race, ethnicity, poverty level and state.
The North American Association of Central Cancer Registries (NAACCR), the American Cancer Society (ACS), the Centers for Disease Control and Prevention (CDC), and the National Cancer Institute (NCI), part of the National Institutes of Health, have collaborated since 1998 to produce the Annual Report to the Nation on the Status of Cancer.
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 each state’s 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 U.S.
Information on newly diagnosed cancer cases occurring in the U.S. is based on data collected by registries in the NCI's Surveillance, Epidemiology, and End Results (SEER) Program and CDC's National Program of Cancer Registries (NPCR). NAACCR evaluates data annually from the registries of both programs and provides combined data for this analysis.
Long-term (1992-2011) overall incidence trends for all cancer sites combined, childhood cancers, and for the 15 most common cancers were based on SEER incidence data covering about 14 percent of the U.S. population. Data from combined SEER and NPCR population-based cancer registries were used to estimate cancer incidence rates and 10-year (2002-2011) trends for five major racial and ethnic groups: white, black, Asian and Pacific Islander, American Indian/Alaska Native, and Hispanic. For the period 2007-2011, 48 registries, covering 97 percent of the U.S. population, met NAACCR data quality criteria, and for the time period 2002–2011, 42 registries (covering 93 percent of the U.S. population) met these criteria.
Which reporting periods were chosen as a main focus of the report?
The period from 2007-2011 was used for describing the U.S. burden of cancer rates, and the period from 2002-2011 was used for describing trends in cancer incidence and death rates for five major racial and ethnic groups. The period from 1975-2011 was chosen to provide the best perspective on long-term trends in cancer death rates among all races combined, while the period from 1992-2011 was chosen to provide the best perspective on long-term incidence trends.
What is detailed in the special feature section of this year’s report?
In this year’s special feature section, the authors highlight newly available data on national female breast cancer incidence rates by tumor characteristics for four common molecular subtypes that are based on hormone receptor expression (either HR+ or HR-) and/or epithelial cell of origin (luminal or basal). The epithelium is the layer of cells that line or cover internal organs; basal cells (or base) are found in the lower part of the epidermis and luminal cells, the most common type, line the mammary ducts. There are two HR+ breast cancers (Luminal A and Luminal B) and two HR- cancers (basal-like and human growth factor-neu receptor (HER2)-enriched). Understanding the extent of each type of breast cancer in the population by subtype is increasingly important for guiding treatment, predicting survival, and developing prevention plans. The molecular subtypes can be approximated by HR/HER2 status; i.e., Luminal A (HR+/HER2-), Luminal B (HR+/HER2+), HER2-enriched (HR-/HER2+), and triple negative (HR-/HER2-).
Beginning with cases diagnosed in 2010, all population-based cancer registries in the U.S. were required to report both HR and HER2 status for breast cancer cases. This report uses the most current data available, which includes data from 42 states plus the District of Columbia, making this the most comprehensive analysis of breast cancer subtype incidence available. A recent, large-scale U.S. analysis of breast cancer subtypes using 2010 HR/HER2 data was conducted using registries covering 28 percent of the U.S. population (Ref.: Howlader N, et al. JNCI, 2014). The analysis confirmed results from prior small studies by subtype that documented demographic patterns of the two main subtypes and showed HR+/HER2- to be the most common subtype and HR-/HER2- (commonly called triple negative) being more common in younger women and non-Hispanic black women than in other age or racial/ethnic groups.
Update on Incidence and Mortality Trends for All Cancer Sites Combined and the Most Common Cancers
What is happening with cancer incidence trends overall?
Incidence rates represent the number of reported new cases over a period of time per 100,000 people in the general population. From 2002-2011, age-adjusted incidence rates for all cancers combined declined 0.5 percent per year for both sexes in the U.S. For the period 2007 to 2011, among men, incidence rates decreased 1.8 percent. Overall incidence rates increased 0.8 percent from 1992 to 1998 among women but were steady from 1998 to 2011. As has been the case since 1992, overall incidence rates increased by 0.8 percent per year among children 14 years of age or younger as well as for children 0-19 years of age.
While declines in cancer mortality rates are always good news, changes in incidence rates may represent both good and bad news. Declines in cancer incidence rates that occur as a result of decreased modifiable risk factors or increased use of screening tests (colorectal and cervical cancer screening) that allow the detection and removal of precancerous lesions are good news. However, a drop in screening rates can also make it appear that incidence rates are lower while in fact some cancers will not be detected early and may not be discovered until they are at a more advanced stage.
Note that findings are presented for the top 17 cancers among men and top 18 cancers among women in order to accommodate the top 15 cancers for all races and ethnicities combined and for each major racial and ethnic group. Cancer represents over a hundred different types of diseases, based on where it occurs in the body as well as the biological features of the tumor. The report uses broad groupings to present cancer statistics on rates and trends. In the Special Feature however, as the understanding of the biological and genetic features of breast cancer has evolved and is reported in medical records, experts are now revising and stratifying how breast cancers are grouped for statistical reporting. The hope is that this newer type of reporting and classification can expand to include many other types of cancer.
What is happening with cancer mortality trends overall?
Overall age-adjusted cancer death rates continued to decline, a trend that began in the early 1990s. From 2002 to 2011, death rates decreased by 1.8 percent per year among men, by 1.4 percent per year among women, by 2.1 percent per year among children ages 0-14, and by 2.3 percent per year among children 0-19 years of age. Age-adjusted death rates are the best indicator of progress against cancer, although other measures, such as quality of life, are also important.
During the most recent 10-year period (2002-2011), death rates among men decreased for 10 of the 17 most common cancers (lung, prostate, colon and rectum, leukemia, non-Hodgkin lymphoma, esophagus, kidney, stomach, myeloma, and larynx) and increased for four others (cancer of the pancreas, liver, melanoma, and soft tissue including heart). During the corresponding time period, death rates among females decreased for 13 of the top cancers (lung, breast, colorectal, ovary, leukemia, non-Hodgkin lymphoma, brain, kidney, stomach, cervix, bladder, esophagus, and oral), whereas they increased from 2002 to 2011 for cancers of the pancreas, uterus, and liver. After decreasing for many years, cancer death rates stabilized during 2007 to 2011 for myeloma among females and for bladder, brain, and oral cancers among males.
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 (for example, the number of deaths per 100,000 people in the U.S.) and are adjusted for age so they can be compared across groups that vary by factors such as race, time period, and regions with different age structures (i.e., some areas have higher concentrations of older people while others have more young people). 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 U.S. (cancer is primarily a disease of aging), as well as an increase in the size of the population.
Therefore, although the cancer death rate may go down during a particular period, the actual number of cancer deaths could go up because the number of older Americans is increasing and the overall size of the population is increasing.
Tracking Breast Cancer Subtypes
Why is knowledge of breast cancer subtypes important?
A 2015 study conducted among 500 women in California who had been diagnosed with breast cancer between 2010 and 2011 found that women often don't know their subtype diagnosis (Ref.: Freedman RA, et al. Cancer. 2015). A better knowledge of their molecular subtypes might help women understand treatment decisions and assist them with medication compliance. According to the authors of the California study, cancer patients who understand the basis for their treatment are generally more satisfied with that treatment.
Based on their medical records, only 56 percent of women reported their correct estrogen status, 58 percent reported their correct HER2 status and 57 percent reported their correct stage, which is a measure of how advanced their cancer is. Only about one in five women reported their correct grade, which is a definition of the pathology, or cellular appearance, of their cancer. Lack of knowledge of all of these factors was more pronounced among minority women.
What did this report find about the demographics of subtypes?
This report found that the breast cancer subtype HR+/HER2- was the most common, with an age-adjusted rate of 86.5 per 100,000 women in the U.S. This rate was six times higher than triple-negative breast cancer rates of 15.5, seven times higher than the HR+/HER2+ breast cancer rate of 12.4, and 16 times higher than the HR-/HER2+ breast cancer rate of 5.5. In every racial and ethnic group, rates for HR+/HER2- breast cancers were higher than any other subtype and the HR+/HER2- rate was highest for non-Hispanic white women (92.7 per 100,000 women in the U.S.). Rates for triple-negative breast cancers (HR-/HER2-) were highest among non-Hispanic black women compared with all other racial/ethnic groups, with an age-adjusted rate of 27.2 per 100,000 women in the U.S.
For women, the following represents the distribution of breast cancer cases in the U.S.:
- HR+/HER- represents 73 percent of all breast cancer cases
- Triple-negative represents 13 percent of all breast cancer cases
- HR+/HER2+ represents 10 percent of all breast cancer cases
- HR-/HER2+ represents 5 percent of all breast cancer cases
Breast cancers of all subtypes were most commonly diagnosed at a local stage and least commonly diagnosed at a distant stage in all racial and ethnic groups. Non-Hispanic black women had the highest rate of breast cancer diagnosed at a distant stage across every subtype.
Did breast cancer subtypes vary by income level or geographic area?
Breast cancer rates of HR+/HER2- decreased with increasing poverty levels for every racial and ethnic group with the highest rate, 98.7 per 100,000, for non-Hispanic white women living in low poverty areas. There were no clear relationships between census tract-based poverty and incidence for the other subtypes for any race/ethnicity.
State-level triple-negative breast cancers rates were lower in the northwest and higher in the southeast. Rates of HR+/HER2+ breast cancer were higher than the national rate in Idaho, Tennessee, and Pennsylvania and lower in Colorado, Florida, Hawaii, Kentucky, Maine, South Dakota, and Virginia. For HR-/HER2+ breast cancer, no states had rates that were statistically different from the national rate. It should be noted that geographic variation is driven by many factors, and the state-level differences must be interpreted carefully. Incidence rates of HR+/HER2- breast cancers were generally higher in states with higher mammography screening.
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 people 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.
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 mentioned in the text are statistically significant unless noted otherwise. For non-statistically significant trends, terms such as "stable," "non-significant increase," and "non-significant decrease" were used.
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, particularly in the most recent years for which data are available. Cancer registries routinely take two years 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 when they are diagnosed in outpatient settings. Cancer registries continue to update incidence rates to include these cases. Consequently, the data initially reported for certain cancer incidence rates may be an underestimate.
Long-term reporting patterns in NCI’s SEER (Surveillance, Epidemiology and End Results) registries have been analyzed and it is now possible to adjust incidence rates for all cancers combined and for site-specific cancers with a correction for expected reporting delays and more complete information. However, SEER registries do not cover the entire population, thus combined data from SEER and CDC’s National Program of Cancer Registries (which is not delay-adjusted) are important for assessing the incidence of cancer in the U.S.
Why was this report published in 2015 and why was there no report published in 2014?
The Annual Report was last published on December 16, 2013 (see http://onlinelibrary.wiley.com/doi/10.1002/cncr.27514/abstract) in Cancer. Publication dates are determined by journal editors and sometimes publication is delayed for a variety of reasons, thus leading to a delay in the publication of this most recent report.