Risk factors and temporal patterns of recurrences in patients with vulvar cancer: implications for follow-up intervals and duration

Background To date, information on risk factors and temporal patterns of recurrences in patients with vulvar cancer is sparse. Conclusive data for an optimal surveillance strategy are lacking. Methods This multicenter, retrospective population-based register study included 1412 patients who have been treated from 2000 to 2017 for vulvar cancer in the German districts of Upper Palatinate, Lower Bavaria, and Saxony-Anhalt. Kaplan-Meier method, and univariate and multivariate Cox regression were employed to evaluate prognostic factors and temporal course of overall survival, cumulative recurrence, and recurrence-free survival rates. Results After exclusion, the final study cohort comprised 829 patients. Most recurrences occurred within the first 3 years after diagnosis. Notably, a significant subset of patients were recurrent even after 5 years. The cumulative recurrence rate from all relapses was 18.6% 1 year after primary diagnosis. The recurrence rate increased to 34.7% after 3, to 41.8% after 5, and to 56.6% after 10 years post-diagnosis. The risk of relapse was significantly increased in patients over 70 years of age (hazard ratio (HR) = 2.7; p < 0.001; 95% CI 1.6-4.4), and in patients with positive nodal status N1 (HR = 2.0; p = 0.019; 95% CI 1.1-3.5) and N2/3 (HR = 2.2; p = 0.033; 95% CI 1.1-4.4). Conclusion Our study provides compelling evidence that follow-up care should be carried out for longer than 5 years, especially for high-risk patients.