Poster Presentation Australasian Melanoma Conference 2018

Effect of a previous diagnosis of primary invasive melanoma on the progression of subsequent primary invasive melanoma (#104)

Sharene Chong 1 2 , Adele Green 3 , Casey Rowe 4 , Maryrose Malt 3 , Susan Brown 5 , Mark Smithers 2 , Kiarash Khosrotehrani 1
  1. University of Queensland Diamantina Institute, Woolloongabba, QLD, Australia
  2. Princess Alexandra Hospital, Woolloongabba, QLD, Australia
  3. QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia
  4. Royal Brisbane and Women's Hospital, Herston, Queensland, Australia
  5. University of Queensland Centre for Clinical Research, Herston, Queensland, Australia

Cutaneous melanoma is on the rise globally, with Australia and New Zealand having the highest incidence resulting in a significant proportion of patients developing more than one melanoma. We and others have shown recently that patients with multiple invasive melanomas have a poorer survival as compared to those with a single invasive melanoma of equivalent characteristics. We looked at the profile of progression of patients with multiple melanomas in terms of sentinel lymph node (SLN) status of their subsequent melanomas to understand the reasons for the poorer survival.

651 patients with stage Ib and II primary cutaneous melanoma referred to the Princess Alexandra Hospital between 1994 and 2011 who underwent a sentinel lymph node biopsy were included in our study. Information on their index melanoma leading to the sentinel lymph node biopsy, and any melanomas before and after were collected and analysed. 

Having a previous stage II melanoma significantly correlated with increased age at diagnosis of index melanoma, head and neck sites, increased recurrence and melanoma-specific death. Using Cox proportional hazards model with sex, Breslow thickness, ulceration and SLN status as covariates, additional stage II melanoma before index melanoma had an increased hazard ratio (HR) of 3.50 (95% CI 0.85-14.45, P = 0.084). When we confined the cohort to stage II index melanomas, additional stage II melanoma before index melanoma had a HR of 3.87 (95% CI 1.19-12.56, P=0.024). Patients with previous stage II melanoma had a significantly increased association with positive SLN status compared to those with single invasive melanoma (40.0% vs 15.1%, p<0.001). 

Our study validated that having a previous stage II melanoma had worse outcomes for patients, with a significantly increased rate of SLN positivity in their subsequent melanoma. These findings support a trend towards more aggressive behaviour of melanomas occurring in patients with a previous history of invasive melanoma starting at the very early level of lymph node invasion. This highlights the importance of better understanding of the pattern of progression of subsequent melanomas, patient education in the melanoma survivor population to ensure proactive attitudes towards follow up care, as well as closer surveillance to diagnose any subsequent melanomas at an early stage.