EPA's Report on the Environment: External Review Draft
Note to reviewers of this draft revised ROE: This indicator reflects data through 2009. EPA anticipates updating this indicator in 2014.
The term “cancer” is used to characterize diseases in which abnormal cells divide without control. A cancerous cell loses its ability to regulate its own growth, control cell division, and communicate with other cells. Cancer cells can invade nearby tissues and can spread through the bloodstream and lymphatic system to other parts of the body (NCI, n.d.). The risk of developing cancer increases with age. Environmental exposures, genetic predisposition, certain viruses, and socioeconomic factors may all play a role in the development and progression of the disease.
For the U.S. population, age-adjusted cancer incidence rates for all sites combined were stable between 1992 and 2009 for men and women overall and for all racial and ethnic populations (Jemal et al., 2013). Nevertheless, cancer continues to be the second leading cause of death in the U.S., accounting for about 23 percent of all deaths in 2009 (General Mortality indicator). Many different types of cancer exist. These can develop in various organs and tissues within the body and contributing causal factors can vary depending on the cancer site and type. Therefore, tracking rates for individual cancer sites is more meaningful when evaluating cancer trends.
Many factors are known to contribute, or are suspected of contributing, to cancer risk. These include lifestyle factors (for instance, tobacco and alcohol use), exposures on the job, or other environmental exposures, including medical exposures. These factors may contribute individually (i.e., additively) or synergistically (i.e., producing an effect greater than the sum of each factor acting alone) to the development of cancer. Further, the cancer hazard to any individual is dependent on the amount and duration of exposure and the individual’s susceptibility to a particular substance. Only in a small number of cases is it known what specific exposures or conditions are responsible for the onset and development of cancers (NTP, 2011).
This indicator presents cancer incidence rates for the U.S. population from 1973 to 2009 using data collected through the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) Program. The SEER Program collects and publishes cancer incidence and survival data from 18 population-based cancer registries, including state, central, metropolitan, and Alaska Native registries, which cover approximately 28 percent of the U.S. population (NCI, 2011). The 10 most commonly diagnosed cancer sites presented are based on 2009 data compiled from SEER. Site classifications (e.g., lung and bronchus, colon and rectum) were compared to the American Cancer Society’s “leading sites” classification to ensure consistency in how data are presented (ACS, 2012).
What the Data Show
Although a slow steady increase in cancer incidence generally occurred between 1973 and 1992, peaking in 1992 with an age-adjusted cancer incidence of 511 cases per 100,000, overall incidence rates appear to have remained stable or slowly declined over the last 10 years. Some differences exist in incidence rates across age, sex, and racial groups (Exhibit 1).
During 2009, those ages 65 and older had the highest incidence rates (2,088 cases per 100,000) compared to all other age categories. Total (all sites combined) cancer incidence rates are higher for males compared to females and for blacks compared to whites (Exhibit 1). The age-adjusted cancer incidence rate in 2009 for blacks was 499 cases per 100,000 compared to 469 cases per 100,000 for whites; the age-adjusted cancer incidence rate in 2009 was 527 cases per 100,000 for males compared to 422 cases per 100,000 among females.
Exhibits 2 and 3 show the differences between the top 10 cancer sites in males and females, respectively. For both, the top three cancers represent over half of all newly identified cancer cases in 2009. Among the most notable differences is the rate of urinary bladder cancer, which continues to be the fourth leading cancer identified among males (36.2 cases per 100,000 in 2009). This rate is more than four times that of females (8.6 cases per 100,000 in 2009) (data not shown). Melanoma of the skin is also higher among males (28.7 cases per 100,000) than females (18.3 cases per 100,000). In 2009, thyroid cancer continued as the fifth leading cancer in females (21.4 cases per 100,000), but is not among the top 10 for males (6.9 cases per 100,000) (data not shown).
Exhibit 4 displays trends for the top six cancers in males between 1973 and 2009. Prostate cancer incidence rates increased dramatically between 1986 and the early 1990s, with a decline in rates between 1992 and 1995. This increase is likely due to the introduction of serum prostate-specific antigen testing for the early detection and screening of prostate cancer (Hankey et al., 1999). Colon and rectum, lung and bronchus, urinary bladder, and non-Hodgkin’s lymphoma have either been relatively stable or have showed a small decline over the last decade. The incidence rate of melanoma of the skin exceeded that of non-Hodgkin’s lymphoma for the last five years (2005-2009).
Recent trends (i.e., since 1995) among the less prevalent site-specific cancers in males show small increases in the incidence rates, with cancers of the kidney and renal pelvis ranging from 15.1 (1997) to 20.5 (2009) cases per 100,000. Overall, slightly decreasing incidence rates were observed for leukemia, which ranged from 17.7 (1995) to 16.1 (2009) cases per 100,000, and cancers of the oral cavity and pharynx (oral cavity), which ranged from 17.8 (1996) to 16.1 (2009) cases per 100,000. (Data not shown.)
As shown in Exhibit 5, among females, breast cancer remains the leading cancer and incidence rates have generally increased from 1973 to 1999, with a small but notable overall decline after 1999. While lung and bronchus is the second leading cancer among men and women in 2009, rates among men have slowly declined over the past decade and rates among women are beginning to stabilize.
The incidence rate of colon and rectum cancer among women increased between 1973 and 1985, but has generally declined slowly since. The incidence of uterine (corpus uteri) cancer in females was relatively stable since the mid 1980s, ranging from 23.2 (1988) to 26.7 (2009) cases per 100,000. The incidence rate of melanoma of the skin has slowly increased since 1999, but has been surpassed since 2007 by thyroid cancer.
Recent (i.e., since 1995) trends in cancer incidence rates among the less prevalent site-specific cancers in females showed an increase in kidney and renal cancer, which ranged from 7.6 (1997) to 10.9 (2008) cases per 100,000. Incidence rates decreased for cancers of the ovary, which ranged from 12.7 (2008 and 2009) to 14.7 (1997 and 1999) cases per 100,000. (Data not shown.)
- SEER data cover approximately 28 percent of the U.S. population, though it is designed to be representative of the entire U.S. population.
- Incidence data generated from SEER are updated annually. There may be changes in the numerator (e.g., revised counts of newly identified cases) or denominator (e.g., revised population counts) numbers that result in small changes in the overall incidence rates for the same year, depending on when a query is run within the SEER database. For example, the SEER database queried in 2009 generating incidence rates for the year 2000 may provide different incidence rates than the database queried in 2008 for the year 2000.
Cancer incidence data for this indicator were obtained by querying the National Cancer Institute’s SEER Program database through its Cancer Query System (CanQues) (NCI, 2012), available at http://seer.cancer.gov/canques/incidence.html.
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