Poster Presentation Clinical Oncology Society of Australia Annual Scientific Meeting 2026

Trends in risk factor exposure in relation to trends in early-onset cancers in Australia (146438)

Peter Sarich 1 , Yoon-Jung Kang 1 , Lara Petelin 1 2 , Paul Grogan 1 , Vivienne Milch 3 4 , Eleonora Feletto 1 , Carolyn Nickson 1 2 3 , Karen Canfell 1 , Marianne Weber 1
  1. Cancer Elimination Collaboration, University of Sydney, Newtown, NSW, Australia
  2. The University of Melbourne, Melbourne, VIC, Australia
  3. Cancer Australia, Sydney, NSW, Australia
  4. Caring Futures Institute, Flinders University, Adelaide, SA, Australia

Background: Incidence rates of early-onset cancers (EOC; diagnosed ages 20-49 years) have increased for 12 'priority cancers' – breast, cervical, colorectal, kidney, pancreatic, prostate, testicular, thyroid and uterine cancers, Hodgkin lymphoma, leukaemia and neuroendocrine neoplasms. The causes of increasing incidence are not well understood.

Methods: We examined established risk factors for these cancers reported by the International Agency for Research on Cancer (IARC) and the World Cancer Research Fund (WCRF), plus potential emerging risk factors as identified through a systematic scoping review. For each risk factor, we sourced Australian sex- and age-specific exposure prevalence data for people aged <50 from government reports and published and grey literature. Risk factors were classified as having prevalence trends: (1) consistent with contributing to increasing EOC incidence; 2) not consistent; or 3) Inconclusive.

Results: A total of 117 unique risk factors were examined – 100 reported by IARC or WCRF and a further 17 identified in our scoping review. Of these, 11 had prevalence trends consistent with contributing to increases in EOC (e.g. increased overweight/obesity, decreased cervical cancer screening participation, decreased dietary fibre intake), 18 had prevalence trends not consistent with contributing to increases in EOC (e.g. decreased alcohol and tobacco use). The remaining risk factors were considered inconclusive (e.g. infections, medications, environmental/occupational exposures).

Conclusions: Several identified risk factors may partly explain EOC trends in Australia, while several are less likely to have contributed. We were unable to assess many risk factors due to lack of quality prevalence data, and we did not account for lag time between exposures and outcomes. There is an urgent need for improved monitoring of established and potential risk factors for EOC in Australia, including dietary, pharmacological and environmental factors. This work can inform future public health interventions targeting exposure to relevant risk factors in younger people.