Background: There is strong epidemiological evidence that obesity is linked to an increased risk of multiple cancers, including colorectal, kidney, pancreatic, liver, thyroid, multiple myeloma, and several female reproductive cancers. Recent emerging global evidence suggests that obesity-related cancer rates are increasing among younger adult populations. However, there is currently limited research examining the prevalence and trends of obesity-related cancer (ORC) among young South Australian adults.
Aim: To examine 40-year trends in obesity-related cancer incidence among South Australians aged 20â49 years.
Methods: Data were drawn from the South Australian Cancer Registry (SACR). Population-based cancer incidence data (SACR, 1982â2021) were analysed for 12 previously identified obesity-related cancer types. Trends were evaluated for all obesity-related cancers combined and for site-specific obesity-related cancer types for 5-year periods using age-specific rates per 100,000 population and linear regression for trend significance.
Results:
⢠All obesity-related cancers combined increased significantly from 43.0 to 79.1 per 100,000 between 1982â86 and 2017â21 (p<0.0001).Â
⢠Strong upward trends were observed for colorectal, kidney, pancreatic, thyroid, uterine corpus, breast cancer, multiple myeloma, and liver cancers, with the steepest increases in thyroid (from 3.1 to 10.0 per 100,000) and colorectal cancer (from 8.7 to 15.9).Â
⢠Females exhibited consistently higher ORC rates than males, driven by breast, uterine, thyroid and ovarian cancers.
Conclusion: Over the past 40 years, obesity-related cancers have increased significantly, almost doubling during this observation period among South Australians under 50. These data mirror international trends linking early-life obesity with early-onset cancer risk. The sustained upward trajectory warrants future public health efforts to target cancer prevention among young South Australians.
Implications for Prevention: These findings reinforce the need for primordial prevention achieved through legislative and policy actions addressing obesogenic food and physical activity environments, and mass-media campaigns emphasising the risks of obesity in young adults.