In a study using SEER (Surveillance, Epidemiology, and End Results) registry data reported in JAMA Network Open, Koh et al found that the incidence of cancer among individuals in the United States younger than age 50 years—defined as early-onset cancer—increased significantly between 2010 and 2019. Incidence was highest for breast cancer, and the greatest increase in incidence was observed for gastrointestinal cancers.
Study Details
The study involved data from 17 SEER registries on persons diagnosed with cancer at age < 50 years between January 1, 2010, and December 31, 2019. Age-standardized incidence rates per 100,000 people were extracted for early-onset cancers; rates were age-adjusted to the U.S. standard population.
Key Findings
Among 562,145 patients included in the analysis (57.7% aged 40 to 49 years, 62.5% female), 4,565 (0.8%) were American Indian/Alaska Natives; 54,876 (9.8%) were Asian/Pacific Islanders; 61,048 (10.9%) were Black; 118,099 (21.0%) were Hispanic; 314,610 (56.0%) were White; and 8,947 (1.6%) were of unknown race and/or ethnicity.
Between 2010 and 2019, the age-standardized incidence rate of early-onset cancer increased significantly among all individuals (annual percentage change [APC] = 0.28%, 95% confidence interval [CI] = 0.09%–0.47%, P = .01) and among females (APC = 0.67%, 95% CI = 0.39%–0.94%, P = .001), but decreased significantly among males (APC = −0.37%, 95% CI = −0.51% to −0.22%, P < .001). By comparison, the age-standardized incidence rate of cancers in individuals aged ≥ 50 years in SEER data decreased significantly over the study period (APC = −0.87%, 95% CI = −1.06% to −0.67%, P < .001).
Mean annual percentage changes increased in American Indian/Alaska Native (1.97%, 95% CI = 0.69%–3.27%, P < .001), Asian/Pacific Islander (0.97%, 95% CI = 0.58%–1.35%, P = .007), and Hispanic patients (1.43%, 95% CI = 1.05%–1.81%, P < .001); were stable in White patients (0.04%, 95% CI = −0.24% to 0.31%, P = .77); and decreased in Black patients (−0.47%, 95% CI = −0.77% to −0.17%, P = .007).
In 2019, the highest number of incident cases of early-onset disease were breast (n = 12,649), thyroid (n = 5,869), and colon/rectal (n = 4,097) cancers.
From 2010 to 2019, gastrointestinal cancers had the greatest increase in incidence rates among all early-onset cancer groups (APC = 2.16%, 95% CI = 1.66%–2.67%, P < .001). Those with the greatest increases were appendiceal (APC = 15.61%, 95% CI = 9.21%–22.38%, P < .001), intrahepatic bile duct (APC = 8.12%, 95% CI = 4.94%–11.39%, P < .001), and pancreatic cancers (APC = 2.53%, 95% CI = 1.69%–3.38%, P < .001). Incidence rates decreased for liver cancer (APC = −4.67%, 95% CI = −5.70% to −3.63%, P < .001) and remained stable for esophageal cancer (APC = −0.94%, 95% CI = −2.56% to 0.71%, P = .22).
The greatest decreases in incidence rates were observed for cancer in the floor of the mouth (APC = −7.58%, 95% CI = −9.59% to −5.52%, P < .001), acute monocytic leukemia (APC = −6.51%, 95% CI = −8.86% to −4.11%, P < .001), and prostate cancer (APC = −6.12%, 95% CI = −8.16% to −4.04%, P < .001).
The investigators concluded: “In this cohort study, the incidence rates of early-onset cancer increased from 2010 to 2019. Although breast cancer had the highest number of incident cases, gastrointestinal cancers had the fastest-growing incidence rates among all early-onset cancers. These data may be useful for the development of surveillance strategies and funding priorities.”
Daniel Q. Huang, MBBS, MMED, and Cheng Han Ng, MBBS, of the Yong Loo Lin School of Medicine, National University of Singapore, are the corresponding authors for the JAMA Network Open article.
Disclosure: The study was supported by the National Center for Advancing Translational Sciences, National Institute of Diabetes and Digestive and Kidney Diseases, National Medical Research Council of the Singapore Ministry of Health, and others. For full disclosures of the study authors, visit jamanetwork.com.
