Tumor-free margins and local recurrence in squamous cell carcinoma of the vulva

Objective: To investigate the relation of pathologic tumor-free margins and local recurrence in patients who underwent primary surgery for vulvar squamous cell carcinoma. Methods: In this retrospective analysis, patients with stage I-III vulvar squamous cell carcinoma who underwent primary surgery between 2000 and 2018 were identified from the Mayo Clinic Cancer Registry. Results: A total of 335 patients were included and divided into three groups according to tumor-free margins: group 1 (<3 mm, n = 32); group 2 (≥3 to <8 mm, n = 151); group 3 (≥8 mm, n = 152). The median follow-up time was 73 months (range 2–240). A total of 78 (23.3%) patients developed local recurrence. With the inverse propensity score weighing method adjusting baseline characters, margins <8 mm had inferior local control (HR 1.98, 95% CI 1.13–3.41). The 5-year local disease-free survival (DFS) was 48.2%, 81.5% and 84.6% for group 1, 2 and 3 respectively (p < 0.001). There were no differences in groin lymph nodes relapse (p = 0.850), distant metastases (p = 0.253), or disease-specific survival (DSS) (p = 0.289) among the three groups. Margins <8 mm, midline involvement, multifocal disease, precancerous lesions on margins and depth of invasion >1 mm were found to be poor prognosticators for local DFS in univariate analysis. Multifocal disease was the strongest predictor for local recurrence in multivariate analysis (HR 4.32, 95% CI 2.67–6.99). Conclusion: Patients undergoing primary surgery for vulvar squamous cell carcinoma with tumor free-margins <8 mm have a higher local recurrence rate.