Annual Report to the Nation on the Status of Cancer, 1975-2006, Featuring Trends in Colorectal Cancer: Questions and Answers
- Incidence rates for all cancers combined decreased 0.7 percent per year from 1999 through 2006 for both sexes. (Question 5)
- Death rates decreased, on average, 1.6 percent per year from 2001 through 2006. (Question 8)
- Long-term incidence trends for colorectal cancer (CRC) have been fairly consistent in men and women. (Question 11)
- Incidence and death rates differ by race/ethnicity and sex. CRC had the third highest incidence rate across all U.S. populations, except for Hispanic men and Black, Asian and Pacific Islander, and Hispanic women, in which it ranked second. (Questions 12,14)
What is the purpose of this report and who created it?
This report provides an update of cancer incidence (new cases) and death rates and trends in these rates in the United States, as well as an in-depth analysis of a colorectal cancer trends and projections. The National Cancer Institute (NCI), which is part of the National Institutes of Health, the American Cancer Society (ACS), the North American Association of Central Cancer Registries (NAACCR), and the Centers for Disease Control and Prevention (CDC), have collaborated annually since 1998 to create this report.
The feature section of the report describes colorectal cancer (CRC) rates and trends, as well as modeling projections for future CRC rates across the United States.
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 United States 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. Incidence rates are for invasive cancers, except for bladder cancer, which also includes in situ cancer (cancer that is confined to the inner lining of the bladder).
Long-term (1975 through 2006) trends for all races for all cancer sites combined and for the 15 most common cancers were based on SEER incidence data covering about 10 percent of the U.S. population. Short-term trends (1996 through 2006) for five racial/ethnic populations (white, black, Asian and Pacific Islander [API], American Indian/Alaska Native [AI/AN] and Hispanic/Latino) by sex for all sites combined and for the 15 most common cancers were based on data from SEER and NPCR registries. This report includes about 71 percent of the U.S. population. Average annual (2002 through 2006), sex-specific, and age-adjusted incidence rates were based on incidence data from 43 population-based cancer registries that cover about 86 percent of the U.S. population.
Which reporting periods were chosen as a main focus of the report?
The period from 2002 through 2006 was used for describing the U.S. burden of cancer, and the period from 1997 through 2006 was used for describing trends in cancer incidence and death among the country's five major racial and ethnic populations (white, black, Asian and Pacific Islander, Hispanic/Latino, and American Indian/Alaska Native). The period from 1975 through 2006 was chosen to represent the best perspective on long-term trends in cancer incidence and death rates among all races combined.
What is detailed in the Special Feature of this year's report?
In this year's Special Feature on Colorectal Cancer Trends and Impact of Interventions (Risk Factors, Screening, and Treatment) to Reduce Future Rates, the authors used microsimulation population-level modeling projections to show that with accelerated cancer control there could be an overall mortality reduction of 50 percent by 2020. To project future trends, the researchers considered three possible scenarios. In the first, risk factors, as well as screening and treatment rates, stayed exactly the same as they were in the year 2000. In the second scenario, they assumed that these variables would continue on their current trend, increasing or decreasing at a steady rate. In the third scenario, risk factors, screening and treatment all improved at a plausibly optimistic rate. The modeling projections show that declines in colorectal cancer death rates are consistent with a relatively large contribution from screening and with a smaller, but demonstrable impact, of risk factor reductions and improved treatments.
Update on Incidence and Mortality Trends for All Cancer Sites Combined and the Top 15 Cancers
What is happening with cancer incidence trends overall?
After increasing from 1975 through 1992, incidence rates for all cancers combined for both sexes and all populations were stable from 1992 through 1999 and decreased 0.7 percent from 1999 through 2006. Declines in incidence rates among men were again steeper than among women. For men, incidence rates for all cancers decreased by 1.3 percent per year from 2000 through 2006. For women, incidence rates for all cancers combined decreased 0.5 percent from 1998 through 2006.
The decreases resulted largely from declines in both incidence and death rates for the three most common cancers in men (i.e., lung, prostate and colorectal cancer) and for two of the three leading cancers in women (i.e., breast cancer and colorectal cancer).
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) or bad news (decreased use of screening tests) or a combination of the two.
What is happening with incidence rates for the top 15 cancers among men and women?
Among men, incidence rates of myeloma, leukemia, melanoma, and cancers of the liver, kidney, and esophagus increased in the most recent periods. The average annual change showed prostate cancer incidence rates decreased by 2.4 percent from 2000 through 2006, after a small, non-significant increase from 1995 through 2000. Incidence rates also decreased for cancers of the lung, oral cavity, brain/nervous system, stomach, and colorectum. Rates were stable for the remaining top 15 cancers (cancers of the bladder, pancreas, and non-Hodgkin lymphoma) in the most recent time period.
Among women, incidence rates increased during the most recent periods for non-Hodgkin lymphoma, melanoma, leukemia, and cancers of the bladder, kidney, thyroid, pancreas, and lung. Incidence rates decreased for cancers of the breast, colorectum, uterus, ovary, cervix, and oral cavity.
What is happening with incidence rates for breast cancer?
Breast cancer rates, which increased 1.6 percent per year from 1994 through 1999, saw an annual decrease of 2.0 percent for 1999 through 2006. 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.
What is happening with cancer mortality trends overall?
The overall decline in cancer death rates, first noted in the 1990s, has continued through 2006. Death rates decreased on average 1.6 percent per year from 2001 through 2006, continuing the trend that was seen with the annual decrease of 1.1 percent per year from 1993 through 2001. This decline was slightly more pronounced among men (2 percent per year from 2001 through 2006) than women (1.5 percent per year from 2002 through 2006). 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?
For the most recent reporting period, which varies according to cancer type, death rates decreased for both men and women in colorectal, stomach, kidney, and brain cancers, as well as for leukemia, non-Hodgkin lymphoma and myeloma. Death rates decreased for men in lung, prostate, and oral cavity cancer, and for women in breast, ovary, and bladder cancer. For men, mortality increased for melanoma and esophageal cancer, and for women mortality increased in pancreatic cancer. Liver cancer mortality increased for both men and 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 U.S.) 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 U.S. 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.
Trends in Colorectal Cancer (CRC)
What is happening with incidence rates for colorectal cancer?
Long-term incidence trends for colorectal cancer (CRC) have been fairly consistent in men and women. CRC incidence increased for men from 1975 through 1985, declined from 1985 through 1995 for men and women, saw a short, non-significant increase from 1995 through 1998, and declined markedly from 1998 through 2006. The fastest annual rate of decline occurred among men and women 65 years of age and older. Short-term incidence trends increased annually for people less than 50 years of age within most population groups with few exceptions.
How do CRC incidence rates differ by race/ethnicity and sex?
For all cancer sites in men, CRC had the third highest incidence rate across all U.S. populations, except Hispanic men, in which it had the second highest incidence rate. For all cancer sites in women, CRC had the third highest rate for all races combined and for white, non-Hispanic, and American Indian/Alaskan Native (AI/AN) women. However, for black, Asian and Pacific Islander (API), and Hispanic women, CRC ranked second and lung cancer ranked third.
Incidence rates by major anatomic sub-sites (proximal colon, distal colon, rectum) varied considerably by race, sex, and age. For all ages, incidence rates for distal colon (the portion of the colon that a scope would examine after passing the rectum) and rectal cancers decreased among men and women in every racial/ethnic group, except for distal colon cancer among AI/AN men and women. In contrast, among people younger than 50, incidence rates for distal colon and rectal cancers increased in men and women of all race/ethnicities combined, in white men and women, and in black men. Rates for proximal colon (the portion of the colon that a scope would examine if it could go past the distal colon) cancer decreased in men and women of all race/ethnicities combined, but decreased by subgroup only for white men and women, API men, and Hispanic women.
Screening has had considerable impact on reducing CRC incidence and mortality, and research regarding the most effective screening methods, persons most at risk, and optimal surveillance intervals is ongoing.
What is happening with death rates for CRC?
CRC death rates have declined since 1984 in men and since 1975 in women, with an accelerated rate of decline since 2002 (for men) and 2001 (for women).
Microsimulation modeling, a technique used to project trends and impacts of screening and other factors on colorectal cancer mortality, shows that screening largely contributed to declines in CRC death rates. Reduction of some risk factors and improved treatments had smaller but demonstrable impacts on the decline in death rates.
How do CRC death rates differ by race/ethnicity and sex?
Death rates for all cancers combined from 2002 through 2006 were highest for black men and women and lowest for API men and women. Lung, prostate and colorectal cancers were among the three leading causes of cancer death for men in each major racial/ethnic group, except for API men, for whom liver cancer ranked second. Among most women, the leading causes of cancer death were lung, breast,, colorectal and pancreatic cancers. However, among Hispanic women, breast cancer was the leading cause of cancer death.
From 1997 through 2006, short-term trends in death rates for all cancers combined decreased for all racial/ethnic groups and for both men and women, except for AI/AN women. Mortality trends decreased for all racial/ethnic groups of men for CRC except among AI/AN men, and CRC death rates decreased for all women except those who were Hispanic or AI/AN.
What are the different methods for screening for CRC?
Recent studies have found similar benefit from several screening methods, including colonoscopy every 10 years, annual high-sensitivity fecal occult blodd testing (FOBT), and flexible sigmoidoscopy every five years along with a highly-sensitive FOBT every two to three years. In addition, computed tomography colonography ("virtual colonoscopy") has been found to be potentially as effective as colonoscopy if conducted every five years with follow-up for any polyps greater than six-millimeters. For colorectal cancer screening to be beneficial, resources must be available to patients who screen positive, including follow-up colonoscopy, diagnostic colonoscopy for symptomatic patients, and surveillance colonoscopy after diagnosis of cancer. Individuals with certain risk factors, such as a family history of colorectal cancer or a personal history of colorectal cancer, colorectal polyps, chronic inflammatory bowel disease, Crohn's disease, or certain inherited genetic conditions may be advised to begin screening earlier than the general population.
A State-of-the-Science conference hosted by the National Institutes of Health, scheduled for February 2010, will focus on ways to enhance the use and quality of colorectal cancer screening.
What are the primary risk factors for CRC and how can they be modified?
Modification of certain risk factors, such as physical inactivity, being overweight and obese, and consumption of a diet high in red and processed meat requires difficult behavioral changes, but should lead to decreased prevalence of colorectal cancer as well as many other positive health outcomes in the long term. In addition, though the 2004 Surgeon General's report on smoking didn't classify colorectal cancer as smoking-related, there is increasing evidence that smoking increases the risk of adenomatous polyps (benign polyps which can progress to cancer), and may be associated with rectal cancer. Declines in tobacco use in the U.S. should contribute to declining trends in new colorectal cancer cases.
Changes in community factors and health policy are also necessary for changing health behaviors. National policy programs are needed that engage communities in order to improve nutrition and physical activity, promote smoking cessation, and decrease alcohol abuse. To address these needs, the CDC has recently published policy and communication strategies for community-level initiatives to promote healthy lifestyles and decrease obesity through increasing availability of affordable, healthy foods and beverages; encouraging physical activity among youth and adults; and promoting environments that support physical activity, such as walking or biking. The program fosters partnerships and collaborations to implement the strategies and evaluate outcomes to assess progress towards a healthier nation.
How is the impact of risk factors, screening, and treatment on future CRC incidence and mortality trends assessed?
A microsimulation model, MISCAN-Colon, from the NCI-sponsored Cancer Intervention and Surveillance Modeling Network (CISNET) consortium, was used to estimate the impact of historical changes in risk factors, screening, and treatment on past CRC incidence and mortality trends and to project future mortality trends through 2020. The MISCAN-Colon model simulated the U.S. population from 1975 to 2020 at risk for CRC based on the sequence of developments as an adenoma becomes cancer. MISCAN-Colon models the impact of risk factors (e.g., smoking, obesity, red meat consumption), screening (fecal occult blood testing and endoscopy), and treatment (chemotherapy regimens) on CRC trends, as well as factors that may decrease CRC risk: aspirin use, multivitamin use, including supplemental folate and calcium, and physical activity.
As risk factor inputs for the model, the authors assumed smoking rates over time of 42 percent in 1965, 23 percent in 2000, and projections of 11 percent to 17 percent in 2020. They assumed obesity rates over time of 13 percent in 1965, 31 percent in 2000, and projections of 34 percent to 45 percent in 2020. Screening rates for FOBT and endoscopy for persons age 50 and older were based on National Health Interview Survey data from 1987, 1992, 1998, and 2000. They also assumed screening rates of 24 percent for FOBT and 39 percent for endoscopy in 2000 and projected estimates for screening prevalence of 35 percent to 38 percent for FOBT and 56 percent to 61 percent for endoscopy in 2020.
To model the impact of treatment, MISCAN-Colon distinguished four chemotherapy regimens for stage III and IV CRC, depending on the treatment available to U.S. patients diagnosed in different periods. Increasing CRC treatment rates over time were assumed, with a projected rate of eight percent of patients in 2005, and 45 percent to 83 percent by 2020, being treated with combination chemotherapy regimens.
To project future CRC trends, MISCAN-Colon modeled three hypothetical scenarios: frozen trends, in which risk factor, screening and treatment rates plateau at the year 2000; continued trends, in which risk factor, screening and treatment rates continue to improve annually at the current rate; and optimistic trends where all three interventions of risk factors, screening and treatment improved at a rate that was considered optimistic but realistic. For the frozen trends scenario, the MISCAN-Colon model predicted the decline in CRC mortality may only be 17 percent. However, if current trends in risk factors, screening, and treatment continued, the MISCAN-Colon model predicted a 36 percent overall decline in CRC mortality from 2000 to 2020. The model predicted an overall mortality decline of 50 percent by 2020 if projected trends in risk factor modification, FOBT and endoscopy screening, and treatment were accelerated.
Where can I find out more about colorectal cancer prevention and screening programs?
In September 2009, the CDC awarded funds to 26 states and tribal organizations to provide colorectal cancer screening services for low-income people ages 50 to 64 who are underinsured or uninsured.
The states receiving five-year awards were: Alabama, Arizona, California, Colorado, Connecticut, Delaware, Florida, Iowa, Maine, Maryland, Massachusetts, Minnesota, Montana, Nebraska, New Hampshire, New Mexico, New York, Oregon, Pennsylvania, South Dakota, Utah, and Washington. The tribal organizations receiving awards were: Alaska Native Tribal Health Consortium, Arctic Slope Native Association, South Puget Intertribal Planning Agency, and Southcentral Foundation.
The funding will support screening and diagnostic follow-up care, data collection and tracking, public education and outreach, provider education, and an evaluation to measure the clinical outcomes, costs, and effectiveness of the program. The awardees can choose from among any of the recommended screenings for colorectal cancer -- colonoscopy, sigmoidoscopy and stool testing -- and are expected to begin screening patients for colorectal cancer within six months of award. For additional information, visit http://www.cdc.gov/cancer/crccp.
CDC's multiyear Screen for Life: National Colorectal Cancer Action Campaign informs men and women age 50 years or older about the importance of having regular colorectal cancer screening tests. Screening tests can find precancerous polyps so they can be removed before they have a chance to turn into cancer, thus preventing the disease. However, an estimated 40 percent of adults age 50 or older -- the age group at greatest risk of developing colorectal cancer -- have not been screened appropriately. For additional information, visit http://www.cdc.gov/cancer/colorectal/sfl.
How to Read This Report
How are cancer incidence and death rates presented?
Cancer incidence rates and death rates are 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.
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 one 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 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 period of multiple years. In describing long- and short-term trends with APC and AAPC estimates, all trends described as "increasing" or "decreasing" are statistically significant unless otherwise noted. Non-significant trends may be described as "level," "stable," "non-significant decrease" or "non-significant increase".
Based on long-term trends (1975-2006), the AAPCs for the most recent five years, 2002 through 2006, were similar to the APCs for the most recent time period. As expected, when the incidence trend fluctuated over time, the 10-year (1997-2006) AAPCs differed from the most recent APCs, e.g., all sites combined for men and women, and cancers of the prostate, pancreas and colorectum in men, and cancers of the breast, pancreas, ovary, and colorectum in women.
Similar to incidence trends, the AAPCs in death rates for 2002 through 2006 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. Some examples are the accelerated rate of decline for colorectal cancer mortality for men and for women and the recent shift to increasing mortality in melanoma among men.
Why were incidence 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 melanoma and prostate and breast cancers, 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. Thus, for death rates for all cancers combined among men, the slope, or trend, is two percent per year decline from 2001 through 2006. Among women, the trend is reported as a 1.5 percent per year decline from 2002 through 2006 in this report.
Joinpoint analyses were performed for incidence and mortality trends from 1975 through 2006.
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 2000 through 2006 are based on new, improved methodology, which affected some state-level incidence rates for 2006. In addition, NCI had to make modifications to these estimates to account, at the county level, for changes in population due to the displacement of victims of hurricanes Katrina and Rita (2005) in the most affected counties of Louisiana, Mississippi, Alabama, and Texas.
Incidence data for 2005 and 2006 were affected by data sharing restrictions within the Veterans Health Administration (VHA) that went into effect in 2007. 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 three percent and possibly as much as eight 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.
The assessment of stage-specific CRC incidence trends was limited by a change in methods used by state registries to collect information on stage beginning with 2004 diagnoses. Therefore, the NCI SEER Program's SEER 9 database was used to estimate stage-specific CRC incidence trends.
The MISCAN-Colon model utilized inputs from previously published results. The report did not re-examine assumptions about risk factors, screening, and treatment interventions. Additional MISCAN-Colon modeling group studies will examine screening trends and other factors not incorporated into earlier models.
Where is this report published?
To view the full report, go to http://onlinelibrary.wiley.com/doi/10.1002/cncr.24760/full.
Reference: Edwards BK, Ward E, Kohler BA, Eheman C, Zauber AG, Anderson RN, Jemal A, Schymura MJ, Lansdorp-Vogelaar I, Seeff LC, van Ballegooijen M, Goede SL, Anderson R, Ries LAG . Annual Report to the Nation on the Status of Cancer, 1975-2006, Featuring Colorectal Cancer Trends and Impact of Interventions (Risk Factors, Screening, and Treatment) to Reduce Future Rates. Cancer. Published online Dec. 7, 2009. DOI: 10.1002/cncr.24760.
Where can I find out more about the report?
For more information, visit the following Web sites:
Annual Report to the Nation press release: http://cancer.gov/newscenter/pressreleases/ReportNation2009Release.
For supplemental material, please go to: www.seer.cancer.gov/report_to_nation/1975-2006.
NCI: http://www.cancer.gov and the SEER Homepage: http://www.seer.cancer.gov . Go to http://www.cancer.gov/cancertopics/types/colon-and-rectal for additional colon and rectal cancer information.