The burden of colorectal cancer is shifting to younger individuals as incidence increases in young adults and declines in older age groups, according to Colorectal Cancer Statistics 2020. The median age of diagnosis dropped from 72 in 2001–2002 to 66 in 2015–2016. This finding and other data were shared in the report, published by Rebecca L. Siegel, MPH, and colleagues in CA: A Cancer Journal for Clinicians.

Rebecca L. Siegel, MPH

Trends in Colorectal Cancer Incidence

Colorectal cancer is the third most commonly diagnosed cancer and the third leading cause of cancer death in both men and women in the United States. Rapid declines in colorectal cancer incidence occurred in people age 50 and older during the 2000s, largely because of increased screening with colonoscopy.

In recent years, however, declines in incidence have been confined to people age 65 and older, among whom rates dropped by 3.3% per year from 2011 through 2016. Among those age 50 to 64, declines in incidence of 2% to 3% per year during the 2000s have reversed in recent years, with rates increasing by 1.0% per year during 2011 through 2016. This is similar to the uptick occurring in people younger than 50, in whom incidence rates have been increasing since the mid-1990s and rose by 2.2% per year from 2011 to 2016. These increases likely reflect elevated disease risk in generations born since 1950 that is being carried forward over time as people age—a phenomenon referred to as a birth cohort effect.

Although rising incidence in those under 50 was previously driven by rectal tumors, in the most recent 5 years of data (2012–2016), incidence rates rose by 1.8% per year for tumors in the proximal and distal colon as well as in the rectum. Rising incidence in people younger than 65 is driven by trends in non-Hispanic whites, although rates in American Indians/Alaska Natives are also increasing steeply.

In 2020, there will be about 18,000 cases of colorectal cancer (12%) diagnosed in people under 50—the equivalent of 49 new cases per day. In addition, 3,640 deaths from colorectal cancer (10 per day) are expected in 2020 in this age group, partly owing to delays in diagnosis; one in four patients (26%) younger than 50 is diagnosed with metastatic disease.

Disease-Related Mortality

Colorectal cancer death rates overall have been decreasing since the late 1940s in women, but only since 1980 in men, likely reflecting differences in incidence trends, which are unavailable prior to 1975. However, incidence and mortality trends have been very similar between the sexes over the past 3 decades.

Like incidence, colorectal cancer mortality patterns vary by age, with rapid decreases in the oldest age groups and increasing trends in young adults. Over the past 10 data years (2008–2017), death rates declined by 3% per year in people age 65 and older, but only by 0.6% per year in people age 50 to 64, while increasing by 1.3% per year in those under age 50.

The uptick in colorectal cancer death rates in adults under 50—which is most rapid among non-Hispanic whites (2% per year)—began around 2004, and was preceded by declines of 1% to 2% per year since at least 1975. Rapid declines in overall colorectal cancer death rates of approximately 3% per year during the 2000s decelerated to 1.8% per year from 2012 to 2017, perhaps reflecting slower gains in screening uptake and lower rates of first-time testing, as well as rising trends in young adults.

Differences Among Racial/Ethnic Groups

Wide differences in the prevalence of colorectal cancer risk factors—such as smoking and excess body weight, as well as access to high-quality health care, including screening—result in large disparities. The incidence rate during 2012 to 2016 ranged from a low of 30 per 100,000 among Asian/Pacific Islanders to 46 per 100,000 among blacks and 89 per 100,000 Alaska Natives.

The pattern for mortality is the same, although the magnitude of the disparity is twice as large as that for incidence. For example, colorectal cancer incidence rates are about 20% higher in blacks (46 per 100,000) than in non-Hispanic whites (39 per 100,000), whereas colorectal cancer mortality rates are almost 40% higher in blacks (19 vs 14 per 100,000). Death rates among Alaska Natives (40 per 100,000) are double those among blacks. American Indians/Alaska Natives are the only racial group in which overall colorectal cancer death rates are not declining.

Of all racial/ethnic groups, black patients are the most likely to be diagnosed with distant-stage colorectal cancer (25% vs 20% of non-Hispanic whites and Asians/Pacific Islanders) and also have the lowest overall 5-year survival rate (60% vs 66% among non-Hispanic whites and 68% among Asians/Pacific Islanders). These disparities are largely driven by socioeconomic inequalities that result in differences in access to early detection and the receipt of timely, high-quality treatment.

Screening

Two-thirds (66%) of individuals age 50 and older were current for colorectal cancer screening in 2018, ranging from 58% in Puerto Rico and 60% in Wyoming to 76% in Massachusetts. However, less than half of people aged 50 to 54 were current, which is particularly concerning given increasing colorectal cancer incidence and mortality in this age group. Screening is also low among immigrants who have been in the United States for less than 10 years (26%), people who are uninsured (30%) or Medicaid-insured (53%), and Asian Americans (55%).

“Although overall colorectal cancer incidence and mortality continue to decline, this progress is increasingly confined to older age groups and is marred by vast disparities,” said lead report author Ms. Siegel. “Unfortunately, the tools we currently have that are very effective at reducing the burden of this disease are not being fully utilized. One in three people 50 and older is not up to date on screening; many of them have never been screened at all. We could save countless lives by increasing access to screening in rural and other low-income areas, especially in Alaska, and incentivizing primary care clinicians to ensure that all patients 45 and older are screened, as well as facilitating healthier lifestyles in our communities.”

“Timely diagnosis among young patients remains critical while we await answers to why colorectal cancer incidence is rising in young and middle-aged adults,” concluded Ms. Siegel.

Disclosure: For full disclosures of the study authors, visit acsjournals.onlinelibrary.wiley.com.