Abstract
To better identify melanoma patients who are, at the time of primary melanoma diagnosis, at high risk of developing brain metastases, primary melanoma characteristics were examined as risk factors for brain metastasis development. In a study of two patient cohorts, clinicopathological characteristics prospectively collected at primary cutaneous melanoma diagnosis for patients with/without brain metastasis were assessed in univariate and multivariate analyses using data from two prospectively collected databases: the Melanoma Cooperative Group (MCG) (1972-1982) and the Interdisciplinary Melanoma Cooperative Group (IMCG) (2002-2009). Candidate risk factors were evaluated in association with time to brain metastasis using either the log-rank test or Cox proportional hazards regression analysis with/without considering competing risks. Out of 2341 total patients included in the study, 222 (9.5%) developed brain metastases (median follow-up: 98 months). The median time to brain metastases was 30.5 months and the median survival time after brain metastases was 4 months. Increased hazard ratios (HRs) for brain metastasis were found among thicker (logarithmic value in mm) (MCG: HR=1.97, P<0.0001; IMCG: HR=1.31, P=0.018), ulcerated (MCG: HR=1.93, P=0.01; IMCG: HR=3.14, P<0.0001), and advanced-stage (MCG: HR=2.08, P=0.008; IMCG: HR=2.56, P=0.0002) primary melanomas on the basis of multivariate Cox regression analysis assuming the presence of competing risks. Primary cutaneous melanoma thickness, ulceration, and stage were identified and validated as risk factors associated with time to melanoma brain metastasis.