Long-term survival across Breslow thickness categories: findings from a population-based study of 210 042 Australian melanoma patients

The prognosis of a patient with a primary cutaneous melanoma is known to be related to the Breslow thickness of their tumor. This study sought to determine long-term (30-year) survival rates for the 4 American Joint Committee on Cancer 8th edition T categories by analyzing Australian registry data for 210 042 melanoma patients diagnosed from 1982 to 2014. The 30-year incidence rates of death due to melanoma and nonmelanoma (with 95% confidence intervals [CIs]) were 7.1% (95% CI = 6.9% to 7.3%) and 32.8% (95% CI = 32.3% to 33.3%), respectively. For T2 melanomas, the corresponding rates were 21.6% (95% CI = 21.0% to 22.3%) and 35.6% (95% CI = 34.7% to 36.6%), for T3 melanomas 34.2% (95% CI = 33.4% to 35.1%) and 39.6% (95% CI = 38.5% to 40.8%), and for T4 melanomas 44.3% (95% CI = 43.2% to 45.3%) and 39.6% (95% CI = 38.3% to 41.0%). A plateau in melanoma-related deaths occurred in T4 patients after 20 years, but there were ongoing melanoma-related deaths for the other T categories beyond 30 years. A progressive rise in the risk of death from other causes occurred across all T categories.