The International Agency for Research on Cancer has linked obesity to increases in the development of 13 cancers, including breast, colorectal, kidney, endometrial, thyroid, pancreatic, liver, multiple myeloma, gastric cardia, meningioma, ovarian, esophageal, and gallbladder cancers. Now, a new study has found that in the United States, higher county-level prevalence of obesity rates was associated with increased rates of obesity-related cancers in young adults aged 20 to 49 years, including colorectal, kidney, uterine, and pancreatic cancers. The findings also show that age-standardized incidence rates of these cancers increased between 2010 and 2022 regardless of county-level obesity rates. The study by Shiels et al was presented during the American Association for Cancer Research Special Conference: The Rise of Early-Onset Cancers—Knowledge Gaps and Research Opportunities (Abstract PR008).
Study Methodology
The researchers analyzed incidence data collected from 2010 to 2022 from 21 cancer registries in the Surveillance, Epidemiology, and End Results (SEER) program. They merged SEER-21 data with data from the Centers for Disease Control and Prevention Diabetes Interactive Atlas on the 2015 county-level prevalence of obesity in the United States, categorized into quintiles.
The researchers then estimated average annual percentage changes (AAPCs) in age-standardized rates (ASRs) from 2010 to 2022 using Joinpoint regression, and tested for equality across quintiles of county-level obesity rates among individuals aged 20 to 49.
In addition, the researchers examined the rate ratios of recent ASRs of colorectal, kidney, uterine, and pancreatic cancers, and compared them across quintiles of county-level obesity rates from 2018 to 2022.
Results
The researchers found that between 2010 and 2022, age-standardized rates of each obesity-related cancer increased significantly among individuals aged 20 to 49, including colorectal (AAPC = 2.47%; 95% confidence interval [CI] = 2.12–2.89), kidney (AAPC = 1.69%; 95% CI = 1.02–2.77), uterine (AAPC = 1.94%; 95% CI = 1.50–2.63), and pancreatic (AAPC = 2.02%; 95% CI = 1.74–2.43). In addition, they saw significant increases in AAPCs from 2010 to 2022 for each of these cancers in each quintile of county-level obesity, except for kidney cancer rates in counties with the lowest obesity prevalence.
There were no significant differences in the magnitudes of the AAPCs across county-level quintiles obesity for colorectal cancer (P = .30). While AAPCs differed significantly across quintiles for kidney (P = .05), uterine (P = .03), and pancreatic cancers (P = .01), AAPCs were greatest in the highest quintile of county-level obesity only for kidney cancer.
However, from 2018 to 2022, ASRs in the highest quintile of county-level obesity were significantly higher than in the lowest quintile of county-level obesity for colorectal cancer (rate ratio [RR] = 1.21; 95% CI = 1.17–1.25), pancreatic cancer (RR=1.25; 95% CI = 1.15–1.35), uterine cancer (RR = 1.08; 95% CI = 1.03–1.13) and kidney cancer (RR = 1.73; 95% CI = 1.65–1.80).
“Higher county-level obesity prevalence in the United States was associated with higher ASRs of colorectal, kidney, uterine, and pancreatic cancers in early-onset age groups. Age-standardized incidence rates of these cancers [also] increased during 2010 [to] 2022, regardless of county-level obesity. Future work should examine histologic subtypes and assess whether increases over time in county-level obesity prevalence is associated with a more rapid increase in colorectal, kidney, uterine, and pancreatic cancer rates,” concluded the study authors.
