The impact of lymph node dissection and adjuvant chemotherapy on survival: A nationwide cohort study of patients with clinical early-stage ovarian cancer

Introduction: To establish the impact of lymph node dissection and chemotherapy on survival in patients with early-stage epithelial ovarian cancer (EOC). Methods: All Dutch patients with International Federation of Gynaecology and Obstetrics (FIGO) stage IeIIA and IIIA1 EOC between 2000 and 2012 were included. Data concerning age, stage, tumour grade, histological subtype, hospital type, lymph node dissection, adjuvant chemotherapy and survival were extracted from the Netherlands Cancer Registry. Results: Of 3658 patients included, 1813 (49.6%) had lymph nodes removed. Relative survival of patients with lymph node dissection (including those with lymph node metastases) was significantly better than that of patients without, also after correcting for stage, tumour grade, histology and age (89% and 82%, respectively; relative excess risk [RER], 0.64; 95% confidence interval [CI]: 0.52-0.78). There was a positive correlation between the number of removed lymph nodes and overall survival (after excluding patients with lymph node metastases). Of patients with stage I-IIA EOC who had >= 10 lymph nodes removed, there was no difference in relative survival between those who received chemotherapy and those who did not (RER, 0.51; 95% CI: 0.15-1.64). This was also true for a subgroup of patients with high-risk features (stage IC and IIA and/or tumour grade 3 and/or clear cell histology [RER, 0.90; 95% CI: 0.46-1.99]). Conclusion: Adequate dissection of at least 10 but preferably >= 20 lymph nodes should be standard procedure for the staging of early-stage EOC. Adjuvant chemotherapy after an adequate lymph node dissection does not seem to contribute to a better relative survival.