Colorectal cancer incidence among younger US adults continues to rise
Colorectal cancer diagnoses among individuals aged younger than 50 years continued to increase in the United States over the past decade, according to results of a retrospective study published in Cancer.
The increased incidence — plus the fact younger adults more often present with and die of advanced disease — should be factored into conversations about colorectal cancer screening guidelines, researchers concluded.
“Several studies over the last few years have shown that the incidence rates and the mortality of colorectal cancer [among] younger adults have increased in the U.S. over the past 30 years,” Boone Goodgame, MD, medical director of Shivers Cancer Center, medical director for oncology at Seton Healthcare Family and assistant professor of medicine at The University of Texas at Austin, told HemOnc Today. “We were able to confirm these trends in a larger database that captures the majority of patients in the U.S. with cancer. We showed that this trend has particularly worsened in the last decade.”
Overall incidence of colorectal cancer incidence has decreased in the United States over the past several decades, but SEER data have shown incidence is increasing among individuals aged younger than 50 years.
Last year, the American Cancer Society updated its guidelines to recommend that adults at average risk for colorectal cancer begin screening at age 45 years. However, the U.S. Preventive Services Task Force continues to recommend screening for asymptomatic adults be performed between ages 50 and 75 years.
Virostko and colleagues conducted their study to determine whether the National Cancer Database (NCDB) — which includes more than 70% of new cancer cases in the U.S. — mirrored the trend of earlier colorectal cancer incidence observed in the SEER database, which accounts for 28% of the U.S. population.
The analysis included 1.18 million people diagnosed with colorectal cancer between 2004 and 2015. Of these, 11% (n = 130,165) were diagnosed prior to age 50 years, and 89% (n = 1.05 million) were diagnosed at age 50 years or older.
The percentage of colorectal cancer cases diagnosed among adults aged younger than 50 years increased from 10% in 2004 to 12.2% in 2015 (P < .0001).
Those aged younger than 50 years appeared more likely than those aged 50 years or older to have primary rectal tumors (40% vs. 28.5%; P < .0001). They also were more likely to have stage III disease (28.1% vs. 23.1%; P < .0001) or stage IV disease (23.5% vs. 16.9%; P < .0001).
Younger adults had higher rates of lymph node involvement and metastatic disease. However, the 90-day mortality rate was higher among older patients.
When researchers analyzed colorectal cancer cases among both men and women, results showed an increasing proportion of cases diagnosed at a young age among non-Hispanic whites (P < .001) and Hispanic whites (P < .05) but not among blacks or Asians.
Investigators then stratified ethnic and racial groups by sex. Among men, they only observed a proportional increase in diagnosis prior to age 50 years among non-Hispanic whites (P < .0001). Among women, they observed proportional increases among non-Hispanic whites (P < .001) and Hispanic whites (P < .05).
“I was surprised that — [among] African Americans and Hispanics with colon cancer — 14% and 18.3% respectively were diagnosed before age 50, and this did not change over the decade we studied,” Goodgame said. “The increase in younger cases was predominantly seen [among] persons of white race in nonrural areas, which is difficult to explain.”
The researchers acknowledged study limitations. Unlike the SEER database, the National Cancer Database does not collect population data. Consequently, it cannot calculate incidence or other epidemiologic metrics. In addition, patients with lower socioeconomic status are less likely to be treated at accredited cancer centers represented in the database.
Large prospective studies of individuals aged younger than 50 years “are strongly needed” to help identify those at greatest risk for colorectal cancer, and to provide more insights into the potential benefits, risks and costs of screening for that population, Goodgame and colleagues wrote.
“Cancer is still predominantly a disease of older people and, for this reason, it is frequently missed or diagnosed late in younger people,” Goodgame told HemOnc Today. “[Because] these rates are increasing, physicians and patients need to be more aware of potential cancer symptoms and more vigilant in adhering to screening guidelines.”
Although an increase in diagnoses among any population is concerning, the magnitude of the increase among individuals aged younger than 50 years is small, and colorectal cancers in this age group remain rare, Chyke A. Doubeni, MD, MPH, a USPSTF member who serves as presidential professor and associate professor of epidemiology at University of Pennsylvania, wrote in an accompanying editorial.
Doubeni reiterated the concerns about the NCDB’s limitations.
Because it is not population based, it cannot provide incidence or mortality rates, he wrote. Also, the NCDB may not adequately capture data from individuals from disadvantaged backgrounds, and it captures a greater proportion of younger patients than those aged 65 years or older.
“Because of these limitations, NCDB data are not suited for informing trends in cancer incidence or subgroups disproportionately affected,” Doubeni wrote.
The impact of expanded screening to younger individuals also remains unclear, he added.
“Because the number of colorectal cancer cases from inherited causes is much higher in younger individuals, it is unknown whether screening for sporadic cases in a group with such low disease rates would result in a favorable balance of harms and benefits,” Doubeni wrote. “It is, therefore, imperative that the various hypotheses for increasing colorectal cancer incidence among people younger than 50 years be rigorously tested to determine whether changing the current screening age for people who are not at increased familial risk represents the most appropriate public health response.” – by John DeRosier
Disclosures: The authors report no relevant financial disclosures. Doubeni reports membership on the USPSTF, as well as an author role with UpToDate.