Lymph node metastases as only qualifier for stage IV serous ovarian cancer confers longer survival than other sites of distant disease - a Swedish Gynecologic Cancer Group (SweGCG) study

Background: The International Federation of Gynecology and Obstetrics (FIGO) ovarian cancer staging system includes no sub-stage for lymph nodes (LN) as only distant disease manifestation. We explore the prognostic implication of LN as only stage IV classifier in serous ovarian cancer. Method: This is a nation-wide, population-based study on 551 women with serous stage IV cancers diagnosed between 2009–2014. We compare overall survival (OS) in women with LN as only distant metastatic site to those with pleural metastases only and to patients with other/multiple stage IV manifestations. Cox regression models were used for uni- and multivariable estimations. Results: Of 551stage IV cases, distant metastatic site was registered in 433. Median OS for women with LN (n = 51) was 41.4 months, compared to 25.2 and 26.8 months for patients with pleural (n = 195) or other/multiple (n = 187) distant metastases (p = .0007). The corresponding five-year survival rates were 32, 11 and 22%, respectively. Multivariable analyzes confirmed shorter survival for women with pleural (HR 2.99, p = .001) or other/multiple distant sites (HR 2.67, p = .007), as compared to LN cases. LN only patients lived 9.1 months longer after primary than after interval surgery, but this difference was not significant (p = .245). Conclusion: Women with stage IV serous ovarian cancer having lymph nodes as only distant metastatic site live longer than other stage IV patients.