Incidence of lymph node metastases in clinical early-stage mucinous and seromucinous ovarian carcinoma: a retrospective cohort study

Objective: The use of lymph node sampling during staging procedures in clinical early-stage mucinous ovarian carcinoma (MOC) is an ongoing matter of debate. Furthermore, the incidence of lymph node metastases (LNM) in MOC in relation to tumour grade (G) is unknown. We aimed to determine the incidence of LNM in clinical early-stage MOC per tumour grade. Design: Retrospective study with data from the Dutch Pathology Registry (PALGA). Setting: The Netherlands, 2002–2012. Population or sample: Patients with MOC. Methods: Histology reports on patients with MOC diagnosed in the Netherlands between 2002 and 2012 were obtained from PALGA. Reports were reviewed for diagnosis, tumour grade and presence of LNM. Clinical data, surgery reports and radiology reports of patients with LNM were retrieved from hospital files. Main outcome measures: Incidence of LNM, disease-free survival (DFS). Results: Of 915 patients with MOC, 426 underwent lymph node sampling. Cytoreductive surgery was performed in 267 patients. The other 222 patients received staging without lymph node sampling. In eight of 426 patients, LNM were discovered by sampling. In four of 190 (2.1%) patients with G1 MOC, LNM were present, compared with one of 115 (0.9%) patients with G2 MOC and three of 22 (13.6%) patients with G3 MOC. Tumour grade was not specified in 99 patients. Patients with clinical early-stage MOC had no DFS benefit from lymph node sampling. Conclusions: LNM are rare in early-stage G1 and G2 MOC without clinical suspicion of LNM. Therefore, lymph node sampling can be omitted in these patients. Tweetable abstract: Lymph node sampling can be omitted in clinical early-stage G1 and G2 mucinous ovarian cancer