Prognosis in primary mucinous ovarian carcinoma: focusing on the five pathological findings indicating metastatic mucinous carcinoma to the ovary

OBJECTIVE: Pathological features indicating metastatic mucinous carcinoma to the ovary (MMCO) have been rarely reported in primary mucinous ovarian carcinoma (PMOC). However, little is known about how often they are observed in PMOC and how they relate to patient prognosis. In this study, we investigated the pathological features indicating MMCO in a large cohort of PMOCs and analyzed their association with patient prognosis. METHODS: We reviewed surgically treated PMOC patients diagnosed at the Seoul National University Hospital from 1995 to 2019, according to the updated WHO classification, and investigated the presence of pathological features indicating MMCO. RESULTS: A total of 144 patients with PMOCs were included. The 5 pathological findings indicating MMCO, including an infiltrative invasive pattern, the absence of benign or borderline components, a smaller tumor size, the presence of signet ring cells and the presence of extracellular mucin were observed in PMOC (21.6%, 43.1%, 20.8%, 4.3% and 12.9%, respectively), and were significantly correlated with poor overall and progression-free survival rates in PMOC. The patient’s prognosis worsened as the extent of the infiltrative invasive pattern increased (p<0.001). In addition, the prognostic power was stronger when the 5 pathological factors were analyzed together (new grouping system) than when analyzed individually (p<0.001) and the new grouping system was identified as an independent prognostic factor regardless of FIGO stage. CONCLUSION: Five pathological findings indicating MMCO in PMOC were significantly associated with poor prognosis in PMOC patients. Also, the new grouping system combining these findings was identified as an independent prognostic factor.