The burden of colorectal cancer is swiftly shifting to younger individuals as incidence increases in young adults and declines in older age groups, according to the latest edition of Colorectal Cancer Statistics 2020, a publication of the American Cancer Society.
A sign of the shift: the median age of diagnosis has dropped from age 72 in the late 1980s to 66 during 2015-2016; in other words, half of all new diagnoses are now in people 66 or younger.
Colorectal cancer (CRC) 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 CRC incidence occurred in people 50 and older during the 2000s, largely because of increased screening with colonoscopy, which can prevent cancer by removing premalignant polyps.
In recent years, however, declines in incidence have been confined to people 65 and older, among whom rates dropped by 3.3% per year from 2011 through 2016. Among those 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 under 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 five 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 CRC (12%) diagnosed in people under 50 in 2020, the equivalent of 49 new cases per day. In addition, 3,640 CRC deaths (10 per day) are expected in 2020 in this age group, partly owing to delays in diagnosis; 1 in 4 patients (26%) younger than 50 is diagnosed with metastatic disease compared to 19% of those 65 and older.
CRC 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 three decades.
Like incidence, CRC 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 65 years and older but by only 0.6% per year in people 50 to 64, while increasing by 1.3% per year in those under 50.
The uptick in CRC 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 CRC 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 younger adults. Related Stories
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