A new study observed a shift in the incidence of obesity-associated cancers (OACs) from older patients to younger ones.
“The International Agency for Research on Cancer reports that there is sufficient evidence that excess body adiposity is associated with increased risk for cancer in 13 anatomical sites. A study by the Centers for Disease Control and Prevention reported that 40% of all cancers diagnosed in 2014 were associated with overweight and obesity,” the researchers reported in JAMA Network Open, adding that “from 1988-1994 to 2015-2016, the prevalence of obesity in the United States more than doubled in the 20- to 39-year age group (from 17.7% to 35.7%), whereas it increased from 27.9% to 42.8% in the 40- to 59-year age group and from 23.7% to 41.0% among adults 60 years or older.”
Therefore, the authors sought to analyze trends associated with age, race/ethnicity, and sex and incident OACs.
The study included patients diagnosed with incident OACs and non-OACs from Jan. 1, 2000, through Dec. 31, 2016, using data from the Surveillance, Epidemiology, and End Results 18 (SEER18) database (excluding Alaska Natives). Age-related data were evaluated in three groups: 20–49 years, 50–64 years, and ≥ 65 years. Race/ethnicity data included non-Hispanic white, non-Hispanic black, and Hispanic patients. Data were not included on patients aged < 20 years, so childhood cancers and adolescent patients were not included in the trial. Cases of breast cancer were limited to female patients.
The following OACs were included: colon and rectum (combined as colorectal), female breast, uterus, gallbladder and other biliary, esophagus, stomach, liver and intrahepatic bile duct, pancreas, ovary, kidney and renal pelvis, thyroid, and myeloma. All cancers not identified as OACs were combined as non-OACs.
Final analysis included 2,665,574 incident OAC cases and 3,448,126 incident non-OAC cases. The OAC population was majority-female (70.3%), while non-OAC cases were only 32% female. From 2000 to 2016, OACs and non-OACs both increased among the 50–64-year age group, with significant variations by race and sex: from 25.3% in non-Hispanic white women to nearly 200% in Hispanic men. Changes in OACs in the youngest age group also varied, from –5.9% among non-Hispanic white women to almost 95% in Hispanic women; similarly, in the oldest age group, changes in OACs ranged from 2.5% to 102%, respectively, in the same groups.
Upon logistic regression analysis, patients aged 50–64 years had a greater annual increase of OACs than non OACs, but in the age ≥ 65 years group, OACs decreased over time. In the youngest cohort, the researchers reported, “For both OACs and non-OACs, the percentage of cases in the 20- to 49-year age group decreased significantly over time in all race/ethnicity- and sex-specific strata. For example, for non-Hispanic white men, the annual change in odds for the 20- to 49-year age group decreased by 0.6% for OACs and decreased by 2.5% for non-OACs. The ratio of OAC to non-OAC [odds ratios] of 1.020 (95% CI, 1.018-1.022) implies that non-OACs decreased to a greater extent than OACs.”
The authors concluded that their findings “indicated a shift in the number of OACs to younger age groups.” They recommended that preventative public health interventions be put into place “to prevent and reduce obesity and other known risk factors, to implement individualized screening strategies, and to disrupt the obesity-cancer association.”