Aims: Rare cancers in Australia are less reported in Australia, and it does not account for Indigenous status. We compared the incidence of rare cancers by Indigenous and socioeconomic status in Queensland.
Methods: This is a population-based study among adults aged 18+ with cancer diagnosis recorded in Queensland Cancer Registry during 2012-2015. 10 malignancies from Cancer Council Australia, were listed using the WHO ICD-O-3 histology and typology codes: Adenoid cystic carcinoma, Appendix, ocular Melanoma, gallbladder, neuroendocrine, penile, pseudomyxoma, small bowel, soft tissue sarcoma, ureter. Both individual characteristics including age, sex, country of birth, marital status, occupation, and area-level residential remoteness and socioeconomic disadvantage status were included. The trend of rare cancers incidence and those from digestive and urinary tract during 2012-2015 were compared by Indigenous status. Disparity by Indigenous status, individual and area-level socioeconomic factors were investigated with logistic regression analysis.
Results: A total of 105328 adults with known ethnicity (99.4%) were diagnosed with cancers in Queensland during 2012-2015. 5160 (4.9%) had rare cancers, with the most frequent being malignancies from appendix (n=1681,1.6%), followed by soft-tissue sarcoma (n=1360, 1.2%), neuroendocrine (n=580, 0.6%), and small bowel (n=573, 0.5%). Rare cancer incidence increased among First Nations populations, but not in other Queenslanders, particularly those from tracts. First Nations people were 13% (aOR 1.13, 95% CI 1.08-1.59) more likely to have rare cancers, even high for those from tracts (aOR 1.55, 95% CI 1.22-1.99), after adjusted for other individual and area-level factors. Regional area had registered fewer rare cancers compared to metropolitan areas by 14% (aOR 0.86, 95% CI 0.79-0.95).
Conclusions: Rare cancers diagnosis, especially those from digestive and urinary tracts, increased in First Nations populations in 2012-2015. Rare cancer awareness is needed in the First Nations communities, especially among the higher risk subgroups.