Facility level volume of surgical lymph node assessment for patients with vulvar cancer: A multi-institutional database analysis (368)

Abstract

<b>Objectives:</b> To investigate surgical lymph node assessment (LND) facility level volume for patients with vulvar cancer using a large hospital-based database and evaluate the potential impact on perioperative and survival outcomes. <b>Methods:</b> The National Cancer Database was accessed, and patients who were diagnosed between 2004 and 2016 with a pathologically confirmed invasive vulvar malignancy, who received all treatment at the reporting facility and underwent surgical lymph node assessment (LND) (including lymph node sampling, dissection, or sentinel lymph node biopsy) were identified. Annual LND volume was calculated for facilities that reported at least 12 cases. High-volume facilities were defined as those performing at least ten LND annually. The impact of facility volume on perioperative and survival outcomes was examined in a cohort of patients with apparent stage IB squamous cell carcinoma, and available data on lymph node status from the pathology report. Clinical-pathologic and demographic characteristics of patients managed in low and high-volume facilities were compared with the Chi-square test while overall survival (OS) was compared with the log-rank test. A Cox model was constructed to control for a priori selected confounders. <b>Results:</b> A total of 376 facilities performed at least 12 cases of LND in vulva cancer patients between 2004 and 2016. The median annual facility volume was 2.9 cases; 10^th and 90^th percentiles were 1.81 and 6.41 cases, respectively. Only eight facilities performed at least ten vulvar cancer LND cases annually. The analysis cohort included 10821 patients with apparent stage IB SCC who met the inclusion criteria; 990 (9.1%) were managed at high-volume centers. There was no difference between patients managed in low and high-volume facilities in terms of patient age, insurance status, and presence of comorbid conditions. Rate of lymph node metastases (22.4% vs 24%, p=0.24) and 90-day mortality (1.5% vs 1.4%, p=0.66) were comparable between low and high-volume facilities. The rate of prolonged hospital stay (defined as >3 days) was higher in low-volume facilities (26.2% vs 21.2%, p<0.001); however, the rate of unplanned re-admission 30 days from discharge was lower (5.2% vs 7.8%, p<0.001). There was no difference in OS between low and high-volume facilities (median OS: 106.9 and 108.9 months, respectively, p=0.21). However, patients who had negative lymph nodes who were managed at highvolume facilities had better OS (p=0.024); 5-year OS rates were 80% and 75%, respectively. After controlling for patient age, race, insurance status, presence of comorbid conditions, history of another tumor, tumor size, and status of lymph nodes, there was no difference in OS between low and high-volume centers (HR: 0.93; 95% CI: 0.83, 1.04). <b>Conclusions:</b> The majority of institutions in the United States perform very few LND for vulvar cancer. Although facility volumes do not appear to affect OS, lymph node assessments appear to be more accurate at high-volume centers.