Colorectal cancer statistics, 2017

Overall

In the United States, the annual age-standardized incidence rate for CRC during 2009 through 2013, the most recent years for which data are available, was 40.7 per 100,000 persons, and the mortality rate (2010-2014) was 14.8 per 100,000 persons. Incidence and mortality rates are 30% and 40% higher in men than in women, respectively,20 although the lifetime risk of disease is similar (4.6% vs 4.2%) because women have longer life expectancy. In addition, the sex disparity differs by age. For example, incidence is not significantly different in men and women younger than age 40 years but is almost 50% higher in men than in women ages 55 to 74 years (131.5 vs 90.7 per 100,000). Reasons for higher rates in men are not completely understood but to some extent likely reflect differences in exposures to risk factors and sex hormones, as well as complex interactions between these influences.21, 22

Racial/ethnic disparities

CRC incidence and mortality rates vary substantially by race and ethnicity. Among the 5 major racial/ethnic groups depicted in Figure 1, rates are highest in non-Hispanic blacks (NHBs) and lowest in Asian Americans/Pacific Islanders (APIs) (Fig. 1). During 2009 through 2013, incidence rates in NHBs (49.2 per 100,000) were about 20% higher than those in non-Hispanic whites (NHWs) (40.2 per 100,000) and 50% higher than those in APIs (32.2 per 100,000). Notably, the magnitude of the disparity for mortality is double that for incidence. During 2010 through 2014, CRC death rates in NHBs (20.5 per 100,000) were 40% higher than those in NHWs (14.6 per 100,000) and twice those in APIs (10.3 per 100,000). It is believed that the higher rates in NHBs are largely driven by disproportionately low socioeconomic status, which is associated with a higher risk of CRC incidence and death.23, 24 According to the US Census Bureau, the poverty rate in 2015 was 24% in blacks compared with 9% in NHWs and 11% in Asians.25 Approximately 40% of the socioeconomic disparity in CRC incidence is attributed to a higher prevalence of risk factors, such as obesity, unhealthy diet, and smoking,26 while differences in screening are estimated to account for 40% of the racial disparity.27 The larger mortality disparity reflects inequities in comorbidities, access to care and treatment,28 and perhaps delayed follow-up of screen-detected abnormalities.29

It is important to recognize that the burden of CRC varies greatly within the broadly defined racial/ethnic groups presented in Figure 1. For example, Alaska Natives have CRC incidence (91.1 per 100,000) and mortality (36.7 per 100,000) rates that are about 80% higher than those in blacks and more than double those in other Native American groups combined, among whom rates are similar to NHWs.6 CRC has been the most commonly diagnosed cancer in Alaska Natives since the early 1970s for reasons that are not well understood but may include a traditional diet high in animal fat and low in fruits and vegetables; vitamin D deficiency; and a high prevalence of smoking, obesity, and diabetes.30, 31 Alaska Natives, particularly rural residents, also have a high prevalence of Helicobacter pylori,32 a bacterium primarily associated with inflammation and malignancy in the stomach, but that has also been associated with an increased risk of CRC in some studies.33, 34

Geographic disparities

The striking variation in CRC incidence globally reflects the strong impact of lifestyle factors on the occurrence of this cancer.35 Similarly, wide geographic disparities within the United States have shifted in recent decades. CRC death rates were highest across the Northeast and lowest in the South in the 1970s and 1980s,36 whereas they are currently highest in parts of the South and Midwest and lowest in the West.37 Table 2 shows annual, age-standardized CRC incidence and death rates by state and race/ethnicity. Geographic variation is similar by sex, with the highest rates for NHWs, NHBs, and Hispanics all in Southern states. Geographic patterns of CRC within the United States reflect differences in population demographics and the prevalence of risk factors, as well as the use of screening.

Subsite distribution

Clinical and biologic characteristics, drug response and prognosis differ based on tumor location within the colorectum, suggesting distinct etiologic mechanisms.38-41 As Table 3 indicates, the most common tumor location is the proximal colon (41%), followed by the rectum (28%).8 However, there is striking variation in subsite distribution by sex and age (Fig. 2). Proximal tumor location is more likely in women than in men and increases with age. For example, 57% of CRCs in women aged 80 years and older occur in the proximal colon, versus just 26% in men younger than 50 years. Among men and women younger than 50 years, tumors are most commonly diagnosed in the rectum (41% and 36%, respectively).

Survival and stage distribution

CRC survival rates are presented for men and women combined because they do not vary substantially by sex. The 5-year relative survival rate for patients diagnosed from 2006 to 2012 (all followed through 2013) was 65%.7 Survival declines to 58% at 10 years after diagnosis, although this estimate does not reflect the most recent improvements in detection and treatment because it is based on the experience of patients diagnosed as far back as 2000. Overall five-year survival is slightly higher for patients with rectal tumors (67%) than for those with colon tumors (64%), despite generally higher stage-specific survival for colon tumors, because rectal cancer is more often diagnosed at a localized stage (43% vs 38%) (Table 4).7 Survival also varies based on tumor location within the colon; 5-year survival is higher for patients with distal tumors (69%) than for those with proximal tumors (65%).6 Tumors in the proximal colon are associated with a higher risk of death, even after controlling for stage at diagnosis and treatment.42 Survival is also higher in younger patients; 5-year survival is 69% in those younger than 65 years versus 62% in those aged 65 years and older. This age advantage is larger for those who have rectal tumors (72% vs 60%) than for those who have colon tumors (68% vs 62%).

Localized stage CRC is diagnosed in 39% of patients, for which the 5-year survival rate is 90%. The survival rate declines to 71% and 14% for patients diagnosed with regional and distant-stage disease, respectively.7 Black and AI/AN patients are most likely to be diagnosed with distant-stage disease and have the lowest survival rates for every stage (Fig. 3). Disparities in CRC survival are largely driven by socioeconomic inequalities that result in differences in access to early detection tests and the receipt of timely, high-quality treatment.43-46 Although black patients are less likely than others to receive appropriate surgery, adjuvant chemotherapy, and radiation treatments,47-49 survival is lower in black than in white patients even when treatment is equal.50 A recent study found that tumor presentation at diagnosis played a larger role in survival differences than treatment, estimating that 40% of the racial disparity in colon cancer survival is because of the combined effects of later stage at diagnosis, a higher likelihood of unfavorable tumor characteristics, and more comorbidities among black patients.51 Survival disparities are also evident within racial and ethnic groups. For example, blacks who are privately insured are 46% more likely to survive 5 years after a CRC diagnosis than blacks who are uninsured.52

Incidence

CRC incidence rates increased from 1975 through the mid- 1980s in both men and women but have since decreased with the exception of a slight, unexplained interruption from 1996 to 1998 (Fig. 4).5 Some researchers have attributed the short-term increase, which also occurred in Canada, to the sudden rise in folate levels during the late 1990s after mandatory folic acid fortification of uncooked cereal grains was introduced to reduce the incidence of neural tube defects.53, 54 Folic acid appears to have a complex, paradoxical relation with CRC, in that it is associated with both prevention of new colonic neoplasia and promotion of existing neoplastic lesions.55, 56 Although prospective cohort studies find an inverse association between total dietary folate and CRC,57, 58 randomized controlled trials of folic acid supplements have shown an increased, although not statistically significant, risk of colorectal adenomas59 and no effect on cancer occurrence.60

Trends in CRC incidence are similar by sex but vary by age (Fig. 5). Incidence rates among individuals aged ≥50 years have dropped from a peak of 225.6 (per 100,000) in 1985 to 119.3 in 2013.5 The rate of decline accelerated around the year 2000, particularly in people aged ≥65 years, among whom rates plummeted from 298.3 (per 100,000) in 2000 to 186.8 in 2013 (incidence rate ratio [IRR], 0.63; 95% confidence interval [95% CI], 0.61-0.64). During this time period, incidence in individuals aged ≥50 years declined by 32%, with reductions largest for distal tumors in those aged ≥65 years (IRR, 0.50; 95% CI, 0.48-0.52) and smallest for rectal tumors in those ages 50 to 64 years (IRR, 0.91; 95% CI, 0.85-0.96 in men; IRR, 1.00; 95% CI, 0.93-1.08 in women).6 This compares to 40% declines in rectal tumor incidence in ages ≥65 years (IRR, 0.62; 95% CI, 0.59-0.65 in men; IRR, 0.59; 95% CI, 0.55-0.62 in women).

The age-specific annual percent change in incidence rates from 2000 to 2013 based on SEER data adjusted for delays in case reporting are shown by tumor location, stage at diagnosis, and race/ethnicity in Tables 5, 6, and 7, respectively. Over the past decade of data (2004-2013), incidence rates decreased by an average of 1.4% per year among individuals ages 50 to 64 years and by 4.0% per year among those ages 65 years and older (Table 5). Among individuals ages 65 years and older, the rate of decline was similar regardless of tumor subsite, stage, or race/ethnicity (with the exception of AI/ANs). However, among people ages 50 to 64 years, declines were much slower for those with rectal tumors (Table 5), for distant-stage disease (Table 6), and for APIs and AI/ANs, among whom incidence rates were stable from 2000 through 2013 (Table 7).

Differences in contemporary trends in individuals aged ≥50 years probably partly reflect differences in the uptake of screening.61 NHIS data indicate that receipt of a colonoscopy in the past 10 years increased from 14% in 2000 to 41% in 2013 among individuals ages 50 to 54 years, from 16% to 52% in those ages 55 to 59 years, and from 25% to 63% in those ages 65 years and older.62 From 2013 to 2015, screening with any guideline-recommended test increased from 53% to 58% in individuals ages 50 to 64 years, from 65% to 68% in those ages 65 years and older, and from 59% to 63% in those ages 50 years and older combined (Table 8). This rise, which followed a plateau in screening from 2010 to 2013, translates into an additional 3,785,600 adults (ages 50 years and older) screened in 2015. If screening prevalence remains at the 2015 rather than the 2013 level, an estimated 39,700 additional CRC cases and 37,200 deaths will be prevented through 2030.

CRC incidence in adults ages 50 years and older is declining rapidly in every state, although the rate appears to have stabilized in Arkansas in the most recent data years (Table 9). During 2009 through 2013, the average rate of decline exceeded 5% annually in 7 states (Nebraska, Maine, Rhode Island, Delaware, Massachusetts, South Dakota, and California). Notably, states with the highest incidence rates (Kentucky, Mississippi, and Louisiana) have among the slowest declines. Declines are also slow for rectal tumor incidence in individuals ages 50 to 64 years, among whom rates were stable in 31 of 46 states (with available data) and the District of Columbia.63 The reported CRC screening prevalence in 2014 ranged from 76% in Massachusetts to 58% in Wyoming.

In contrast to the downturns among screening-aged individuals, CRC incidence rates in adults aged <50 years rose by 1.6% from 2000 to 2013 (Table 5), for an overall increase of 22% (from 5.9 to 7.2 per 100,000; IRR, 1.22; 95% CI, 1.17-1.28). The increase was driven solely by tumors in the distal colon (IRR, 1.24; 95% CI, 1.13-1.35) and rectum (IRR, 1.22; 95% CI, 1.13-1.31).6 Incidence increased most rapidly for distant-stage disease, which rose by 3% per year during this time period (Table 6). The rise in early onset CRC occurred in all racial/ethnic groups except APIs (although the increase was not statistically significant in AI/ANs, likely because of small numbers); was largest among NHWs (2.3% per year from 2000 to 2013) (Table 7); and has also been reported in other high-income countries, including Norway,64 Australia,65 and Canada.66 Although causes for this increase have yet to be elucidated, factors thought to have contributed include increased prevalence of excess body weight, as well as changes in lifestyle patterns that precipitated the obesity epidemic, including unhealthy dietary patterns and a sedentary lifestyle.61, 67-70

Mortality

The declining trend in CRC mortality is more long-standing than that for incidence, particularly in women, among whom death rates have been decreasing since the mid-1940s (Fig. 4). In men and women combined, the death rate has dropped 51% from its peak of 28.6 (per 100,000) in 1976 to 14.1 in 2014. Mortality reductions through 2000 are attributed to improvements in treatment (12%), changing patterns in CRC risk factors (35%), and screening uptake (53%).1 Similar to incidence, the decline in death rates accelerated beginning around 2000 and notably has been of sufficient magnitude to overcome the aging and growth of the population, such that the reported number of CRC deaths dropped from a peak of 57,644 in 1995 to 51,651 in 2014 (Fig. 6). From 2000 to 2014, CRC death rates decreased by 34% in individuals aged ≥50 years but increased by 13% in those aged <50 years (Fig. 5).

CRC death rates have been decreasing since at least 1990 in whites, blacks, and APIs and since 2002 in Hispanics, with a similar pace of decline across these groups over the past decade of data. In contrast, death rates have remained stable in AI/ANs (Fig. 7). Progress in reducing CRC death rates has also lagged in the highest poverty areas of the United States, including the lower Mississippi Delta and parts of Appalachia.36, 71

Survival

As of January 1, 2016, almost 1.5 million Americans were alive with a history of CRC.72 Figure 8 depicts trends in survival for colon and rectal cancers separately since the mid–1970s based on data from the 9 oldest SEER registries. (Survival rates and stage distribution presented for the most current time period in this section differ slightly from those presented in Table 4, because they are based on a subset of SEER data with historical coverage.) From the mid-1970s to the most recent time period (2006-2012), the 5-year relative survival rate for all stages combined increased from 51% to 66% for colon cancer and from 48% to 68% for rectal cancer.7 These gains reflect improvements in treatment and earlier detection.73-75 In the SEER 9 areas, the proportion of cases diagnosed at a localized stage increased from 30% during 1975–1977 to 40% during 2006-2012 for colon cancer and from 37% to 44% for rectal cancer.76 Progress in survival may also reflect the increased use of advanced imaging techniques, such as positron emission tomography, which can improve the accuracy of staging and influence treatment decisions.77-79

The largest improvement in survival has been for regional- and distant-stage disease. For example, the 5-year relative survival rate for regional-stage disease increased from 55% during 1975-1977 to 74% during 2006-2012 for patients with colon cancer and from 45% to 70% for those with rectal cancer (Fig. 8). This progress reflects important improvements in treatment, including adjuvant therapy for resectable stage III colon cancer,80-82 preoperative chemoradiation for locally advanced rectal cancer,83, 84 and cancer-directed surgery for advanced CRC.85 Advances in the treatment of liver metastases,86, 87 new therapies (eg, antiepidermal growth factor receptor antibody therapy and bevacizumab),88, 89 and the use of imaging to improve detection of metastatic lesions90 have particularly influenced the survival of patients with distant-stage disease. Between 1989-1992 and 2009-2012, the 2-year relative survival rate for patients diagnosed with distant-stage tumors increased from 21% to 35% for colon cancer and from 22% to 39% for rectal cancer.76 However, strides in the treatment of metastatic disease have been slower for black, Hispanic, and older patients91, 92; for certain molecular subtypes (eg, microsatellite instability-high and KRAS wild type)93, 94; and for patients with right-sided tumors.41