Key Thickness Benchmark Identified for Thin Melanoma Death Risk

Key Takeaways

• Melanomas with a Breslow thickness of 0.8–1.0 mm are associated with a nearly threefold higher risk of melanoma-related death compared to thinner tumors (< 0.8 mm).
• The 20-year melanoma-specific survival rate is significantly lower for patients with tumors in the 0.8–1.0 mm range (87.8%) compared to thinner lesions (94.2%).
• Breslow thickness did not affect the risk of nonmelanoma-related death.

Melanomas with Breslow thickness between 0.8 and 1.0 mm are associated with nearly triple the risk of melanoma-related death compared to thinner melanomas, a new study of Australian registry data reports.

"Most patients who present with primary cutaneous melanomas have thin tumors (≤ 1.0 mm in Breslow thickness, ie, pT1a and pT1b)," the authors wrote. "Although their prognosis is generally considered to be excellent, there is limited precise information on the association of risk of death with specific Breslow measurements in thin lesions."

The retrospective cohort study included 144,447 Australians diagnosed with thin invasive primary melanomas (≤ 1.0 mm Breslow thickness) between 1982 and 2014. The researchers assessed the risk of melanoma-related and nonmelanoma-related deaths based on tumor thickness and stratified patients into subcategories of less than 0.8 mm and 0.8 to 1.0 mm.

Over a median follow-up period of 15 years, the data showed 20-year melanoma-specific survival rate of 94.2% for patients with melanomas under 0.8 mm vs. 87.8% for those with melanomas between 0.8 and 1.0 mm. Tumors in the 0.8 to 1.0 mm range carried an elevated risk for melanoma-related death compared to thinner lesions (there was a subdistribution hazard ratio (SHR) of 2.92 (95% CI, 2.74 to 3.12) for those with melanomas between 0.8 and 1.0 mm vs. thinner melanomas). The significant survival disparity warrants closer monitoring and potentially more aggressive management, according to the researchers. 

"In this study, the risk of melanoma-related death increased significantly for patients with primary tumors of 0.8 to 1.0 mm in thickness," the authors concluded in the paper. "The risk of death from nonmelanoma-related causes was similar across Breslow thicknesses of 0.1 to 1.0 mm. This analysis suggests that a 0.8-mm threshold for guiding the care of patients with thin primary melanomas."

Source:  Lo S, et al. JAMA Dermatology. 2024. Doi:10.1001/jamadermatol.2024.4900