e-Poster Presentation Clinical Oncology Society of Australia Annual Scientific Meeting 2021

The Melanoma Institute Australia (MIA) nomogram for predicting sentinel node positivity in patients with melanoma: influence on clinical practice at MIA (#218)

Zoe Boyer 1 , Emma McCafferty 1 , Alec Winder 2 , Centre of Research Excellence in Melanoma Investigators 3 , Anne Cust 2 4 , Andrea Smith 4 5
  1. Macquarie University, Macquarie Park, New South Wales, Australia
  2. Melanoma Institute Australia, The University of Sydney, North Sydney, New South Wales, Australia
  3. Multiple affiliations, Sydney, New South Wales, and Melbourne, Victoria, Australia
  4. The Daffodil Centre, The University of Sydney, a joint venture with Cancer Council NSW, Sydney, New South Wales, Australia
  5. Australian Institute for Health Innovation, Macquarie University, Macquarie Park, New South Wales, Australia

Aims: In August 2020, Melanoma Institute Australia (MIA) implemented an online risk calculator tool for predicting sentinel lymph node (SLN) positivity in patients with primary cutaneous melanoma. This calculator can more accurately estimate the risk of SLN positivity in patients with melanoma than other available methods. Our study aimed to evaluate whether the implementation and use of the MIA risk calculator has influenced clinical practice at MIA in patients with early-stage (T1a-T2b) melanoma by comparing pre- with post-implementation data.

Methods: Data from 671 consenting patients treated for primary cutaneous melanoma were extracted from the MIA database and analysed using SPSS software (n=383 pre-implementation period from July 2018 to June 2019; n=288 post-implementation period from August 2020 to July 2021). Risk of SLN positivity for both cohorts was calculated using the MIA risk calculator, and patients were stratified into three groups based on the predicted risk of a positive SLN biopsy (≤4%, 5-9% and ≥10%).

Results: Patients with T1a melanoma underwent SLN biopsy at a higher rate following implementation of the risk calculator (1.1% vs. 6.5%, p=0.018); however, none of these patients yielded a positive biopsy result (n=8). No significant differences were observed in other T stage groups or stratified predicted risk groups, for both SLN biopsy rates and SLN positivity between the pre- and post-implementation periods. Younger patients (<40 years) also underwent SLN biopsy at a higher rate following implementation of the risk calculator, but the difference was not significant (28.9% vs. 44.4%, p=0.18). 

Conclusion: Implementation of the MIA calculator influenced the rates of SLN biopsy in patients with T1a melanoma; however, no other significant changes were observed. Further analysis of longer-term data will be necessary to determine the impact of the calculator on accurately predicting SLN positivity in different stage groups whilst avoiding unnecessary morbidity and mortality.