Solar elastosis correlates with high tumor mutation burden and better 5-year disease-specific survival in patients with stage II/III melanoma.

Objective: To evaluate the relation between solar elastosis and tumor mutation burden (TMB) in a large clinically annotated cohort of stage II and III melanoma patients.

Methods: Primary cutaneous melanomas from 469 AJCC (8 edition) stage II and III patients with clinical annotation including outcome at 5 years of diagnosis were histopathologically evaluated for solar elastosis. Next-generation sequencing assay MSK-IMPACT was employed to determine TMB. Analysis by Fisher's exact test, chi-square, and Kruskal-Wallis were performed, as well as uni- and multivariate logistic regression.

Results: Tumors stratified by low and high TMB showed marked and statistically significant differences in presence and extent of associated solar elastosis. Lower risk patient stage (II versus III by AJCC 8 edition) as well as better 5-year melanomaspecific survival (as binary variable of controls-survivors versus cases-dead of disease at 5 years of diagnosis) were associated with severe solar elastosis. On univariate and multivariate logistic regression models, severe solar elastosis predicted significantly decreased odds of dying of melanoma within 5 years of diagnosis (OR 0.60, 95 % CI 0.39-0.89; and OR 0.42, 95 % CI 0.20-0.83, respectively; both p<0.05).

Conclusion: The association of solar elastosis to TMB and 5-year melanoma specific survival points to its potential as a biomarker of clinical relevance that can be assessed by routine histopathology.