Poster Presentation Clinical Oncology Society of Australia Annual Scientific Meeting 2024

Heterogeneity in the distribution of cutaneous T-cell lymphomas (CTCL) across Australia mirrors dermatologist-density and highlights the unique challenges to diagnosis (#366)

Belinda Campbell 1 2 3 , Peter D Baade 4 5 , Paramita Dasgupta 4 5 , Jessica K Cameron 4 5 6 , Sandro V Porceddu 6 7 8 , Miles Prince 1 9 , Karin Thursky 1 10
  1. The Sir Peter MacCallum Department of Oncology, University of Melbourne, Partkville, Victoria, Australia
  2. Department of Clinical Pathology, University of Melbourne, Parkville, Victoria, Australia
  3. Department of Radiation Oncology, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
  4. Viertal Cancer Research Centre, Cancer Council Queensland, Brisbane, Queensland, Australia
  5. Cancer for Data Science, Queensland University of Technology, Brisbane , Queensland, Australia
  6. Faculty of Medicine, University of Queensland, Brisbane, Queensland, Australia
  7. Department of Radiation Oncology, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
  8. Department of Radiology, University of Melbourne, Parkville, Victoria, Australia
  9. Department of Haematology, Peter MacCallum Cancer Centre and Royal Melbouren Hospital, Melbourne, Victoria, Australia
  10. Department of Health Services Research and Implementation Science, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia

Aims:

Cutaneous T-cell lymphomas (CTCL) are typically incurable, cause significant symptom burden and have a prolonged disease course. Unique hurdles to diagnosis arise from the disease rarity, overlapping morphological appearances, low skin biopsy rates, and requirement for clinico-pathological correlation. This study investigates the incidence and geospatial distribution of CTCL in Australia, compares the distribution to all rare cancers, and explores a possible relationship between CTCL incidence and dermatologist-density in Australia.

 

Methods:

Patients with CTCL (diagnosed 1/1/2000-31/12/2019) were sourced from the Australian Cancer Database, a nationwide dataset of mandatorily reported cancers. Patients aged <15 years were excluded. Residential areas were categorized according to federally-defined definitions. Bayesian spatial incidence models were applied.

 

Results:

The age-standardized incidence of CTCL in Australia was 7.7 [95%CI: 7.4-7.9] per million person-years, translating to 285 new cases annually.

Geospatial analyses revealed heterogeneity in the diagnosis rates of CTCL across small areas and between states/territories. Standardized incidence ratios (SIR) were higher than the national average in the more populated capital cities of Sydney, Melbourne, Perth, Brisbane, and especially Adelaide (11.0 diagnoses per million person-years (95%CI: 9.7-12.5)). Diagnosis rates were lower in rural/remote and socio-economically disadvantaged regions.

Notable geographical differences were seen when comparing the distributions of CTCL to all rare cancers, particularly in northern and central Australia and Tasmania where CTCL diagnoses were most rare. Consistencies between reported CTCL distribution and dermatologist-density were observed.

 

Conclusion:

CTCL is rare, with incidence in Australia on the higher end of international reports. There is geographical variability across the country, with incidence often reflecting population density. Geospatial patterns of CTCL differed significantly from that of all rare cancers, highlighting the distinct diagnostic challenges and unmet needs of this patient group. Parallels between CTCL distribution and dermatologist-density suggest that diagnostic-scrutiny and access to specialist care may play critical roles at this national level.