Aims: CTCL are rare malignancies with increasing incidence. Typically incurable and highly morbid, patients with CTCL frequently require multi-lined therapies, over decades. Radiotherapy achieves high response rates, and constitutes the historical cornerstone of CTCL treatment. Total skin electron therapy (TSE) is a highly technical form of radiotherapy, with proven quality-of-life benefits for CTCL patients. However, with the advent of newer skin-directed and systemic therapies, no consensus exists on optimal treatment sequencing. International reports demonstrate wide variation in patterns of care and suggest declining radiotherapy-utilisation first-line. Herein, we investigated the incidence of CTCL and geographical patterns of radiotherapy-utilisation in a state-wide, population-based registry.
Methods: A retrospective study of NSW Cancer Registry dataset for all patients newly diagnosed with CTCL from 2009-2018, with data linkage to the NSW Outpatients Radiotherapy database. Patients with dual malignancies and/or whose closest radiotherapy centre (calculated by ArcGIS) was across NSW borders, were excluded from radiotherapy analyses. Radiotherapy-utilisation included all treatment lines.
Results: 553 patients were newly diagnosed with CTCL in NSW, with incidence of 7.1/million/year (<1 in 14,000 people). Median age at diagnosis was 64 (range, 11-98) years; 61% were men; 1.6% identified as Aboriginal. 33% of all CTCL patients lived in the 2 most disadvantaged Index of Relative Socio-economic Disadvantage quintiles. 13% resided in remote or moderately accessible locations; 16% resided >50km from the nearest radiotherapy centre.
Over 10 years, the radiotherapy-utilisation rate was 29%. Patients residing in highly accessible areas had lowest radiotherapy-utilisation (24%). Regional variation in radiotherapy-utilisation existed between local health districts (range, 9-50%). No pattern was observed between radiotherapy-utilisation and distance to the nearest radiotherapy centre. TSE-utilisation was only 1.8%, over 10 years.
Conclusion: CTCL incidence in NSW was 7.1 per million/year. Overall radiotherapy-utilisation rate was 29%; TSE-utilisation was extremely low. Curiously, radiotherapy-utilisation was lowest in patients living in highly accessible areas, possibly suggesting that referral bias may be a contributing factor.