Researchers report ‘large shift’ in colorectal cancer burden to younger adults
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The burden of colorectal cancer has shifted considerably toward younger individuals over the past few decades, according to American Cancer Society’s Colorectal Cancer Statistics 2020 report published in CA: A Cancer Journal for Clinicians.
The median age of patients at the time of colorectal cancer diagnosis dropped from age 72 years in the early 2000s to age 66 years in 2015 and 2016.
“It is surprising to see changes in median age at diagnosis,” Rebecca L. Siegel, MPH, scientific director for surveillance research at American Cancer Society, told Healio. “That metric doesn’t usually change much. But we are seeing an unusual scenario with colorectal cancer. Rates are declining rapidly in older age groups — those declines are now confined to people aged 65 years and older — while they are increasing simultaneously in younger age groups. That is causing this large shift.”
Colorectal cancer is the second leading cause of cancer-related death in the United States. More than half of all diagnoses and deaths are related to risk factors such as smoking, unhealthy diet, high alcohol consumption, physical inactivity and excess body weight.
Appropriate screening and surveillance can mitigate colorectal cancer morbidity and mortality.
The U.S. Preventive Services Task Force recommends average-risk individuals undergo colorectal cancer screening beginning at age 50 years. In 2018, American Cancer Society lowered its recommended screening age for average-risk individuals, from age 50 years to age 45 years.
Every 3 years, American Cancer Society publishes an update of colorectal cancer incidence based on population-based cancer registries and mortality data from National Center for Health Statistics.
Incidence data are available through 2016, and mortality data are available through 2017.
According to the report, approximately 147,950 individuals in the United States will be diagnosed with colorectal cancer in 2020, and 53,200 will die of the disease this year. These projections include 17,930 cases and 3,640 deaths among people aged younger than 50 years.
Incidence rates decreased by 3.3% annually among individuals aged 65 years and older between 2011 and 2016, but incidence rates increased by 1% annually among those aged 50 to 64 years during that period.
Because individuals aged younger than 50 years are considerably more likely than older adults to be diagnosed with metastatic disease, these findings must serve as a call to action for the medical community, Siegel said.
“We need more research into what is causing the uptick among younger individuals,” Siegel said. “That most likely will take quite a bit of time, but there is a lot that can be done while we are waiting to avert some of the associated morbidity and mortality.”
Strategies must include addressing delays in diagnosis among younger individuals, Siegel said. In some cases, delays arise due to patient factors, such as lack of insurance or lack of a primary care physician. In other cases, physician factors — such as attributing a younger patient’s persistent symptoms to a less serious medical condition — contribute to delays.
There also are implications for oncologists, Siegel added.
“They will be treating people who are outside the typical patient population, and these younger patients have challenges that are not always considered,” she said. “They include the need to preserve fertility and sexual function — which, I would argue, is a larger concern for younger patients who have many more decades of life to live. Younger patients also have increased likelihood of late effects, again because they have a longer lifespan. So, there are many issues that clinicians will need to be more attuned to while we wait for answers about why this is happening.”
The rising incidence among people aged younger than 65 years appeared to be driven by trends among non-Hispanic whites; however, the report's authors noted rates among American Indians and Alaska Natives also are increasing sharply.
Incidence rates between 2012 and 2016 ranged from 30 per 100,000 persons among the Asian/Pacific Islander population to 45.7 per 100,000 among blacks and 89 per 100,000 among Alaska Natives.
“Alaska Natives have incidence rates that are double those of blacks, and their mortality rates are also double those of blacks,” Siegel said. “For context, keep in mind that blacks have a 20% higher incidence rate than whites, so that is a disparity in and of itself. But Alaska Natives often get left out of the conversation, and I think it is important to shine a light on their very high burden for reasons that still are not understood.”
Colorectal cancer death rates declined by 3% annually among adults aged 65 years and older and by 0.6% annually among adults aged 50 to 64 years between 2008 and 2017. They increased by 1.3% annually among individuals aged younger than 50 years during the same time period.
Mortality declines among those aged younger than 50 years appeared highest among blacks. Mortality rates remained stable among American Indians and Alaska Natives. – by John DeRosier and Mark Leiser
For more information:
Rebecca L. Siegel, MPH, can be reached at Surveillance Research, American Cancer Society, 250 Williams St., NW, Atlanta, GA 30303-1002; email: rebecca.siegel@cancer.org.
Disclosures:
Siegel reports employment with the American Cancer Society. Please see the study for all other authors’ relevant financial disclosures.
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Darrell Gray, MD, MPH
This study contributes to the growing base of evidence of rising colorectal cancer incidence among young adults, and it seems to favor the case of advocates who champion initiation of screening at age 45 years among average-risk individuals. Certainly, more work needs to be done to elucidate why this increase in colorectal cancer among young adults is occurring and how we can personalize approaches to screening among those at risk.
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