Cancer incidence registries now cover nearly all of the US population. State-based vital records systems and aggregate national systems regularly report trends in both cancer incidence and mortality, and national surveys routinely monitor cancer-related risk factors in the population. These surveillance systems have documented substantial changes in both risk factors for cancer and in cancer incidence and mortality rates in the United States over the past 3 decades. In 1996, the American Cancer Society (ACS) set an ambitious challenge for the United States: to reduce cancer mortality rates from their apparent peak in 1990 by 50% in the 25-year period ending in 2015.¹ In 1998, the ACS then challenged the United States to also reduce cancer incidence rates from their peak in 1992 by 25% by the year 2015.² In this chapter, we will examine trends in cancer risk factors as well as trends in cancer incidence and mortality rates in the United States over the 25-year period between 1990 and 2015.

Collecting cancer incidence rates is largely a state-based activity in the United States, because cancer is a reportable disease in all states. The Centers for Disease Control and Prevention (CDC) organizes all state-based cancer registries within the National Program of Cancer Registries, which now reports collective data on cancer incidence from over 40 different state-based registries, providing data that meets strict quality standards.³ The National Cancer Institute has supported high-quality cancer incidence and outcomes registration in selected states and cities since 1973 within the Surveillance, Epidemiology, and End Results (SEER) Program.⁴ The most precise measures of long-term trends in cancer incidence come from SEER-9, a set of nine SEER registries that together include about 10% of the US population. The populations included in the SEER-9 registries document the most detailed history of cancer trends beginning in the 1970s based on highly standardized cancer case ascertainment, staging, treatment, and outcomes. Deaths from cancer are well ascertained in all states via state-based vital records, which are aggregated into annual national mortality reports by the CDC’s National Center for Health Statistics.⁵ Each year, the ACS, the National Cancer Institute, and the CDC publish a Report to the Nation on trends in cancer incidence and mortality in the United States.⁶ Trends in the prevalence of behavioral factors that affect cancer risk are tracked by the Health Interview Survey, an ongoing, in-person interview of a nationally representative sample of adults, and in annual reports by the Behavioral Risk Factor Surveillance System, a continuously operating telephone-based survey operated by state departments of health and organized by the CDC.⁷

Understanding the reasons for cancer trends requires understanding trends in cancer-related risk factors. For factors like tobacco, relating trends in exposure to trends in rates is easy, because those effects are large and single. However, for many other cancer risk factors, because effects are much smaller and multifactorial, simple correlations over time are less apparent. In most situations, all that maybe possible are crude qualitative relationships between temporal trends in cancer risk factors and subsequent trends in cancer rates. Statistical methods such as linear regression joinpoint analysis can tell us when inflections in cancer trends occur, but accounting for the precise reasons for changing rates is often impaired by our incomplete knowledge about the interacting impacts of variations in cancer screening, diagnosis, and treatment, and by uncertainties about latencies between interventions and outcomes.⁸

Trends in major cancer risk factors have been mixed (Table 12.1). Although the downward trends in tobacco smoking among adults that began in the 1960s slowed after 1990, there has been a continuing downward trend in the number of cigarettes smoked per day by continuing smokers.⁹ Obesity trends have been adverse among both men and women since the 1970s, with more than a doubling of the prevalence of obesity between 1990 and 2010. Long-term trends in the use of hormone replacement therapy (HRT) are not routinely monitored in the Behavioral Risk Factor Surveillance System (BRFSS), but HRT use increased substantially in the last 2 decades of the 20th century. Then, following the 2002 publication of the Women’s Health Initiative trial, which showed clear adverse effects of HRT, there was a rapid and substantial drop in HRT use.^10,11 The use of endoscopic screening for colorectal cancer (sigmoidoscopy or colonoscopy) has increased substantially in recent years, approximately doubling since the mid 1990s, so that, as of 2010, about two-thirds of Americans age 50 and older reported ever having had an endoscopic examination. Mammography use increased progressively through the 1990s, but mammogram rates then leveled off after 2000.¹² Widespread prostate-specific antigen (PSA) testing began in the mid to late 1980s, then increased substantially during the 1990s. By 2002, a majority of US men age 50 and older reported having been tested.

In this chapter, we describe and discuss cancer trends for the time period 1990 through 2010 using cancer incidence data from the SEER-9 registry (Table 12.2 and Fig. 12.1) and US cancer mortality data from the National Center for Health Statistics (Table 12.3).^4,5 All rates were age-adjusted to the US 2000 standard population by the direct method, using 10-year age intervals.