Oral Presentation Australasian Society for Dermatology Research Annual Scientific Meeting 2024

Predicting time to subsequent melanoma is more relevant than absolute risk for individuals receiving intensive surveillance   (#56)

Sam Kahler 1 , Chantal Rutjes 1 , Clare Primiero 1 , Dilki Jayasinge 2 , Brigid Betz-Stablein 1 , Monika Janda 2 , Aideen McInerney-Leo 1 , H. Peter Soyer 1
  1. Frazer Insitute, The University of Queensland, Dermatology Research Centre, Brisbane, Queensland, Australia
  2. Centre for Health Services Research, Faculty of Medicine, The University of Queensland, Brisbane, Queensland, Australia

Background:

Individuals with a history of melanoma are at greater risk of a subsequent melanoma. Surveillance aims for early detection of the subsequent diagnosis arising months to decades later. Thus, time to subsequent diagnosis may be more relevant than absolute risk derived from prediction models. We identify risk factors that predict time to a subsequent invasive melanoma to personalise surveillance intensity.

Methods:

We retrospectively collected the chronological incidence of histopathology-confirmed melanoma for a high-risk intensive surveillance cohort. Of the 310 individuals followed for 2-20 years since first diagnosis, 72 were selected for a history of multiple primary invasive melanoma. Individuals were stratified by keratinocyte cancer (KC) status and a time to event analysis conducted to identify factors that predicted time from invasive to subsequent invasive melanoma.  

Results:

Of individuals with MPM, KC positive individuals comprised 79% (57/72) and were diagnosed with 163 invasive melanomas (mean=2.9). KC positive individuals with a first diagnosis of invasive melanoma developed an invasive melanoma within 3.4 years (IQR:0.1-5.4). However, if the second melanoma diagnosis was in situ, then the delay to subsequent invasive melanoma was 10.8 years (IQR:4.3-14.8). KC negative individuals (21%, 15/72) and were diagnosed with 45 invasive melanomas (mean=3.0). KC negative individuals with a first diagnosis of invasive melanoma developed a second invasive melanoma within 3.3 years (IQR: 0.1-3.7). However, if the second melanoma diagnosis was in situ, then the delay to subsequent invasive melanoma was 8.2 years (IQR:1.8-11.3). Time to subsequent invasive melanoma was reduced in KC positive individuals with high solar exposure, and increased in KC negative individuals with private health insurance.  

Conclusions:

Two distinct trajectories to subsequent invasive melanoma were defined within a select cohort, including solar exposure for KC positive, and health literacy for KC negative individuals. Detection of melanoma in situ delayed the time until subsequent invasive melanoma.