Colorectal Cancer Incidence Doubled in Younger Adults

The incidence of colorectal cancer (CRC) is rapidly increasing among younger individuals, and the disease is also being diagnosed at more advanced stages in all ages, according to a new report from the American Cancer Society.

Diagnoses in people younger than 55 years doubled from 11% (1 in 10) in 1995 to 20% (1 in 5) in 2019.

In addition, more advanced disease is being diagnosed; the proportion of individuals of all ages presenting with advanced-stage CRC increased from 52% in the mid-2000s to 60% in 2019.

“We know rates are increasing in young people, but it’s alarming to see how rapidly the whole patient population is shifting younger, despite shrinking numbers in the overall population,” said Rebecca Siegel, MPH, senior scientific director of surveillance research at the American Cancer Society and lead author of the report, in a statement.

“The trend toward more advanced disease in people of all ages is also surprising and should motivate everyone 45 and older to get screened,” she added.

The report was published online March 1 in CA: A Cancer Journal for Clinicians.

CRC is the third most commonly diagnosed cancer and the third leading cause of cancer death of both men and women in the United States. It is estimated that there will be 153,020 new cases of CRC in the US in 2023, including 106,970 tumors in the colon and 46,050 in the rectum.

Overall, in 2023, an estimated 153,020 people will be diagnosed with CRC in the US, and of those, 52,550 people will die from the disease.

The incidence of CRC rapidly decreased during the 2000s among people aged 50 and older, largely because of an increase in cancer screening with colonoscopy. But progress slowed during the past decade, and now the trends toward declining incidence is largely confined to those aged 65 and older.

The authors point out that more than half of all cases and deaths are associated with modifiable risk factors, including smoking, an unhealthy diet, high alcohol consumption, physical inactivity, and excess body weight. A large proportion of CRC incidence and mortality is preventable through recommended screening, surveillance, and high-quality treatment.

But it remains unclear why rates are rising among younger adults and why there is a trend toward the disase being initially diagnosed at more advanced stages.

“We have to address why the rates in young adults continue to trend in the wrong direction,” said Ahmedin Jemal, DVM, PhD, senior vice president of surveillance and health equity science at the American Cancer Society and senior author of the study. “We need to invest more in research to uncover the causes of the rising trends and to discover new treatment for advanced-stage diseases to reduce the morbidity and mortality associated with this disease in this young population, who are raising families and supporting other family members.”

Study Findings

For their report, Siegel and colleagues used incidence data from 1995–2019 from 50 states and the District of Columbia. The data came from the Surveillance, Epidemiology, and End Results (SEER) program of the National Cancer Institute and the National Program of Cancer Registries of the US Centers for Disease Control and Prevention, as provided by the North American Association of Central Cancer Registries. National mortality data through 2020 were provided by the National Center for Health Statistics.

The authors note that while overall, deaths from CRC are continuing to fall, “this progress is tempered by a rapidly changing landscape of disease that foreshadows less favorable trends ahead.”

The incidence rates have increased by 2% per year among people younger than 50 years as well as among those aged 50–54 years, while for the past decade, the rates have declined among those aged 65 and older. Incidence rates have stabilized among persons aged 50–64 years.

Although the majority of diagnoses continue to occur among people aged 65 years and older, 19,550 cases (13%) will occur in those younger than age 50 years, and one third will be diagnosed in those aged 50–64 years.

Other key findings include the following:

  • Declines in incidence and mortality have slowed, from 3% to 4% per year during the 2000s to 1% per year for incidence and 2% per year for mortality during the past decade.

  • The incidence rate was 33% higher among men than women from 2015–2019, which may reflect differences in risk factors, such as excess body weight, processed meat consumption, and a history of smoking.

  • The percentage of patients who present with advanced-stage disease has increased from a low of 52% in the mid-2000s to 60% in 2019 despite an increase in the use of screening.

  • Death rates from CRC have risen since around 2005 by 1% annually among those younger than 50 years and by 0.6% in people aged 50–54.

  • The report also identified racial/ethnic differences in incidence and mortality: incidence was highest among Alaska Natives (88.5 per 100,000), American Indians (46.0 per 100,000), and Black persons in comparison with White persons (41.7 per 100,000 vs 35.7 per 100,000). Mortality followed a similar pattern; the highest rates were observed among Alaska Natives (50.5 per 100,000), American Indians (17.5 per 100,000), and Black persons in comparison with White persons (17.6 per 100,000 vs 13.1 per 100,000).

  • There was also a shift to left-sided tumors, despite greater efficacy of screening for preventing left-sided lesions. The proportion of CRCs occurring in the rectum has steadily risen from 27% in 1995 to 31% in 2019.

“These highly concerning data illustrate the urgent need to invest in targeted cancer research studies dedicated to understanding and preventing early-onset colorectal cancer,” said Karen E. Knudsen, MBA, PhD, CEO of the American Cancer Society. “The shift to diagnosis of more advanced disease also underscores the importance of screening and early detection, which saves lives.”

The study was supported by the American Cancer Society.

CA Cancer J Clin. Published online March 1, 2023. Full text

Roxanne Nelson is a registered nurse and an award-winning medical writer who has written for many major news outlets and is a regular contributor to Medscape

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