Role of adjuvant radiation therapy for squamous cell carcinoma (SCC) of the vulva and single lymph node metastasis (159)

Abstract

<b>Objectives:</b> To evaluate the utilization and outcomes of adjuvant radiation therapy for early-stage squamous cell carcinoma of the vulva with single inguinal lymph node metastasis following comprehensive inguinal lymphadenectomy. <b>Methods:</b> The National Cancer Database and patients without a history of another tumor, diagnosed between 2004 and 2015 with T1b squamous cell carcinoma of the vulva who underwent surgical excision and inguinal lymphadenectomy with at least ten lymph nodes removed and had only one positive lymph node per pathology report were identified. Clinical-pathologic and demographic characteristics were compared based on the receipt of adjuvant radiotherapy (defined as receipt of external beam radiation at a dose of at least 50 Gy within six months from surgery). Overall survival (OS) was calculated and compared with the log-rank test following the generation of Kaplan-Meier curves. A Cox model was constructed to control for a priori selected confounders. <b>Results:</b> A total of 250 patients who met the inclusion criteria were identified; 77 (30.8%) received adjuvant radiation therapy at a median of 57 days from surgery (IQR: 22) with a median dose of 50.4 Gy and a median treatment duration of 44 days (IQR: 12), while 32 (41.6%) of them received radio-sensitizing chemotherapy. Patients who received adjuvant radiation were more likely to have tumors ≥4 cm (46.8% vs 29.5%, p=0.046). Patient age, race, insurance status, presence of comorbid conditions, type of treatment facility, tumor grade, and surgical margin status were comparable between the two groups. By univariate analysis, patients who received adjuvant chemoradiation or radiation therapy alone did not have better OS compared to patients who did not receive any treatment (p=0.45); 5-year OS rates were 61.1% compared to 53.4% and 56.5%, respectively. After controlling for patient age, presence of comorbid conditions, insurance status, and tumor size, administration of adjuvant chemoradiation (HR: 0.74, 95% CI: 0.45-1.23) or radiation therapy alone (HR: 0.87, 95% CI: 0.43-1.76) were not associated with a survival benefit. <b>Conclusions:</b> Administration of adjuvant radiation therapy following comprehensive inguinal lymphadenectomy may not be associated with a survival benefit for patients with early-stage SCC of the vulva and single lymph node metastasis.