Uptake and survival outcomes of sentinel lymph node mapping in vulvar melanoma (552)

Abstract

Objectives: With the integration of sentinel lymph node (SLN) mapping into cutaneous melanoma and squamous cell carcinomas, the technique is increasingly being applied to vulvar melanomas. However, little is known about the uptake and outcomes of SLN mapping for vulvar melanoma. We examined the trends in use and survival outcomes for SLN mapping compared to lymph node dissection (LND) for vulvar melanoma. Methods: Patients with vulvar melanoma who underwent surgical resection between 2004 and 2018 in the Surveillance, Epidemiology, and End Results Program (SEER) database were included. TNM staging was used to exclude patients with clinically positive nodes and distant metastasis from the cohort. Performance of lymph node evaluation was classified as SLN mapping, LND, or no nodal evaluation. Kaplan-Meier curves of overall survival and multinominal logistic regression models for predictors of type of lymph node evaluation were created. Inverse probability treatment weighting (IPTW) was used to compare overall survival between the groups. Results: Among 398 patients, SLN mapping was performed in 124 (31.2%), LND in 141 (35.4%), and no lymph node dissection in 133 (33.4%) patients. SLN mapping increased from 8% in 2004 to 45% in 2018 (a 5.6-fold increase), while the rate of LND decreased from 40% to 20% (a 2-fold decrease) over the same period. No nodal dissection decreased from 52% in 2004 to 35% in 2018 (a 1.6-fold decrease) (p<0.03). In a multinomial logistic regression model, stage I disease and older age (>70 years old) were associated with a lower likelihood of SLN mapping (p<0.05). In our propensity score weighted cohort, the median overall survival for SLN mapping was 96 months (95% CI: 54-not reached), 70 months (95% CI: 44 months-151 months) for LND, and 55 months (27 months-140 months) for no nodal evaluation. While there was improved overall survival for SLN mapping (HR: 0.86, 95% CI: 0.46-0.97) as compared to no nodal evaluation, there was no significant difference in overall survival between the cohorts (SLN vs LND: HR: 0.77, 95% CI: 0.53-1.14) (No lymph node evaluation vs LND: HR: 1.16, 95% CI: 0.81-1.67) (p=0.35) (Figure 1). Conclusions: Performance of SLN mapping is increasing rapidly for women with vulvar melanoma. Compared to LND, SLN mapping is not associated with worse overall survival. Objectives: With the integration of sentinel lymph node (SLN) mapping into cutaneous melanoma and squamous cell carcinomas, the technique is increasingly being applied to vulvar melanomas. However, little is known about the uptake and outcomes of SLN mapping for vulvar melanoma. We examined the trends in use and survival outcomes for SLN mapping compared to lymph node dissection (LND) for vulvar melanoma. Methods: Patients with vulvar melanoma who underwent surgical resection between 2004 and 2018 in the Surveillance, Epidemiology, and End Results Program (SEER) database were included. TNM staging was used to exclude patients with clinically positive nodes and distant metastasis from the cohort. Performance of lymph node evaluation was classified as SLN mapping, LND, or no nodal evaluation. Kaplan-Meier curves of overall survival and multinominal logistic regression models for predictors of type of lymph node evaluation were created. Inverse probability treatment weighting (IPTW) was used to compare overall survival between the groups. Results: Among 398 patients, SLN mapping was performed in 124 (31.2%), LND in 141 (35.4%), and no lymph node dissection in 133 (33.4%) patients. SLN mapping increased from 8% in 2004 to 45% in 2018 (a 5.6-fold increase), while the rate of LND decreased from 40% to 20% (a 2-fold decrease) over the same period. No nodal dissection decreased from 52% in 2004 to 35% in 2018 (a 1.6-fold decrease) (p<0.03). In a multinomial logistic regression model, stage I disease and older age (>70 years old) were associated with a lower likelihood of SLN mapping (p<0.05). In our propensity score weighted cohort, the median overall survival for SLN mapping was 96 months (95% CI: 54-not reached), 70 months (95% CI: 44 months-151 months) for LND, and 55 months (27 months-140 months) for no nodal evaluation. While there was improved overall survival for SLN mapping (HR: 0.86, 95% CI: 0.46-0.97) as compared to no nodal evaluation, there was no significant difference in overall survival between the cohorts (SLN vs LND: HR: 0.77, 95% CI: 0.53-1.14) (No lymph node evaluation vs LND: HR: 1.16, 95% CI: 0.81-1.67) (p=0.35) (Figure 1). Conclusions: Performance of SLN mapping is increasing rapidly for women with vulvar melanoma. Compared to LND, SLN mapping is not associated with worse overall survival.