Are Positive Biopsy Margins in Melanoma Significant?: A Cohort Study of Micro- Versus Macroscopic Margin Status and Their Impact on Residual Disease and Survival.

Abstract

Presence of positive biopsy margins in melanoma can provoke anxiety over potential disease progression from delays to surgical excision, but their impact on outcomes is unknown. We aimed to compare the presence of residual melanoma in the surgical excision specimen and survival between patients with negative, microscopically positive, and macroscopically positive biopsy margins. Patients with cutaneous melanoma who underwent surgical excision over a 13-year period were included. Biopsy characteristics, residual disease in the surgical specimen, and overall and recurrence-free survival were compared between patients with negative, microscopically positive (only scar visible), and macroscopically positive (visible remaining melanoma) biopsy margins. Of 901 patients, 42.4%, 33.3%, and 24.3% had negative, microscopically positive, and macroscopically positive margins, respectively. The incidence of residual invasive melanoma in the surgical specimen varied (P < 0.001), occurring in 5.5%, 17.0%, and 74.9% of patients, respectively. Both microscopically and macroscopically positive margins were associated with residual disease (P < 0.001) but only the latter predicted worse overall (P = 0.013) and recurrence-free survival (P = 0.009). Kaplan-Meier estimated survival was comparable between those with negative and microscopically positive margins, but overall (P = 0.006) and recurrence-free survival (P = 0.004) were significantly worse in the macroscopically positive margin group. These patients had worse prognosis melanoma, with 33.8% being stage III disease, and 23.2% having positive sentinel lymph nodes. Patients and physicians may be reassured in the presence of microscopically positive biopsy margins which are not associated with worse survival, However, patients with macroscopically positive margins have poorer prognosis and should be treated within an acceptable time frame.