Impact of adjuvant chemotherapy with radiation for node-positive vulvar cancer: A National Cancer Data Base (NCDB) analysis.

BACKGROUND For node-positive vulvar cancer, adjuvant radiotherapy has an established benefit, whereas the impact of chemotherapy is unknown. A National Cancer Data Base (NCDB) analysis was conducted to determine patterns of care and evaluate the survival impact of adjuvant chemotherapy. METHODS The NCDB was queried for vulvar cancer patients diagnosed from 1998-2011 who underwent extirpative surgery with confirmed inguinal nodal involvement treated with adjuvant radiotherapy. Patients with inadequate follow-up or non-squamous histologies were excluded. Chi-square test, logistic regression analysis, log-rank test and multivariable Cox proportional regression modeling with adjustment using propensity score with inverse probability of treatment weights (IPTW) were conducted to establish factors associated with utilization and survival. RESULTS A total of 1797 patients were identified: 26.3% received adjuvant chemotherapy and 76.6% had 1-3 involved lymph nodes. Adoption of adjuvant chemotherapy significantly increased over time, from 10.8% in 1998 to 41.0% in 2006 (p<0.001). Lower utilization was seen in older patients, Northeast or Southern facilities, and patients with more extensive nodal dissection, whereas greater number of involved nodes, stage IVA disease and positive surgical margins led to a higher probability of receiving chemotherapy. Unadjusted median survival without and with adjuvant chemotherapy was 29.7months and 44.0months (p=0.001). On IPTW-adjusted Cox proportional regression modeling, delivery of adjuvant chemotherapy resulted in a 38% reduction in the risk of death (HR 0.62, 95% CI 0.48-0.79, p<0.001). CONCLUSION In a large population-based analysis, adjuvant chemotherapy resulted in a significant reduction in mortality risk for node-positive vulvar cancer patients who received adjuvant radiotherapy.