Quality of adjuvant radiation therapy and impact on the survival of patients with lymph node-positive squamous cell carcinoma of the vulva.

Objective: Patients with squamous cell carcinoma of the vulva with inguinal lymph node metastases undergo adjuvant treatment to reduce the risk of recurrence. We examined the patterns of adjuvant treatment delivery and their impact on overall survival.

Methods: Patients diagnosed between January 2004 and December 2015 with apparent early-stage squamous cell carcinoma of the vulva, who underwent surgical resection with lymph node sampling/dissection, had at least 1 positive lymph node, and received adjuvant radiation therapy were identified. A total of 3 quality metrics associated with improved survival were evaluated: utilization of radiosensitizing chemotherapy, receipt of radiation therapy within 8 weeks of surgery, and completion of radiation therapy within 8 weeks of initiation. Overall survival was examined after the generation of Kaplan-Meier curves and compared using the log-rank test. A Cox model was constructed to control for the a priori confounding factors.

Results: A total of 1181 patients were identified, with a median number of positive lymph nodes of 2 (range; 1-14). All 3 quality metrics were met by 238 patients (20.2%). These patients were younger (median age, 59 vs 67 years, p<.001), more likely to have private insurance (52.1% vs 33.4%, p<.001), and less likely to have medical co-morbidities (22.7% vs 30.5%; p=.017). Patients who received adjuvant radiotherapy meeting all quality metrics had better overall survival than those who did not (p<.001); the 5-year overall survival rates were 62.6% and 42.8%, respectively. After controlling for patient age, race, insurance status, presence of medical co-morbidities, tumor size, performance of comprehensive lymphadenectomy, and number of positive lymph nodes, adjuvant radiation therapy meeting all quality metrics was associated with better overall survival (HR 0.56, 95% CI 0.44 to 0.72).

Conclusions: Approximately 1 in 5 patients with lymph node-positive vulvar cancer received adjuvant treatment that met all quality metrics associated with improved survival.