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Merkel Cell Carcinoma: Surgical Margin Positivity and Outcomes

By: Jenna Carter, PhD
Posted: Thursday, December 16, 2021

A research letter published in the Journal of the American Academy of Dermatology highlighted findings from a study examining the risk factors for positive surgical margins and their potential impact on survival in patients with Merkel cell carcinoma. Lisa Zaba, MD, PhD, of Stanford University, Palo Alto, California, and colleagues examined these risk factors in patients enlisted in the National Cancer Database; they found that positive margins are a significant driver of survival, even after adjuvant radiation therapy is administered.

“The [National Cancer Database] is a facility-based data set covering approximately 70% of newly diagnosed malignancies each year in the United States. Our inclusion criteria comprised localized [Merkel cell carcinoma] (clinical or pathologic N0 patients) from 2004 to 2017 who received surgical excision,” stated Dr. Zaba and colleagues. “Based on these findings, patients selected for narrow-margin excision should be carefully chosen to minimize the risk of a positive surgical margin.”

A total of 7,609 patients with Merkel cell carcinoma were a part of the study cohort, with 515 having a positive surgical margin. A Kaplan-Meier analysis was performed to assess the impact of surgical margin status and adjuvant radiation therapy on overall survival. Additionally, the investigators used multivariate logistic regression to evaluate the independent factors associated with positive surgical margin and multivariable Cox proportional hazards to identify the independent predictors of overall survival.

Overall findings revealed that when stratified by adjuvant radiation therapy and margin status, there were significant differences in overall survival across the groups, (P < .0001). Specifically, margin positivity was associated with poorer overall survival, even in those who received adjuvant radiation therapy (P = .0005). Additionally, older age, higher comorbidity score, low hospital volume, immunosuppression, and tumor size greater than 2 cm were associated with an increased likelihood of surgical margin positivity.

Disclosure: The study authors reported no conflicts of interest.

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