Histological grading of ovarian mucinous carcinoma – an outcome‐based analysis of traditional and novel systems

Abstract

AimsGrading of primary ovarian mucinous carcinoma (OMC) is inconsistent among practices. The International Collaboration on Cancer Reporting recommends grading OMC using the International Federation of Gynecology and Obstetrics (FIGO) system for endometrial endometrioid carcinoma, when needed. The growth pattern (expansile versus infiltrative), a known prognostic variable in OMC, is not considered in any grading system. We herein analysed the prognostic value of various grading methods in a well‐annotated cohort of OMC.Methods and resultsInstitutional OMCs underwent review and grading by the Silverberg and FIGO schemes and a novel system, growth‐based grading (GBG), defined as G1 (expansile growth or infiltrative invasion in ≤10%) and G2 (infiltrative growth >10% of tumour). Of 46 OMCs included, 80% were FIGO stage I, 11% stage II and 9% stage III. On follow‐up (mean = 52 months, range = 1–190), five patients (11%) had adverse events (three recurrences and four deaths). On univariate analysis, stage (P = 0.01, Cox proportional analysis), Silverberg grade (P = 0.01), GBG grade (P = 0.001) and percentage of infiltrative growth (P < 0.001), but not FIGO grade, correlated with disease‐free survival. Log‐rank analysis showed increased survival in patients with Silverberg grade 1 versus 2 (P < 0.001) and those with GBG G1 versus G2 (P < 0.001). None of the parameters evaluated was significant on multivariate analysis (restricted due to the low number of adverse events).ConclusionsSilverberg and the new GBG system appear to be prognostically significant in OMC. Pattern‐based grading allows for a binary stratification into low‐ and high‐grade categories, which may be more appropriate for patient risk stratification. Despite current practices and recommendations to utilise FIGO grading in OMC, our study shows no prognostic significance of this system and we advise against its use.

Ovarian mucinous and seromucinous neoplasms: problematic aspects and modern diagnostic approach

“…For this reason, the reported prognostic significance of infiltrative invasion in primary ovarian mucinous carcinomas in older studies, where misdiagnosis of metastasis to the ovary as primary ovarian carcinoma could have occurred, has been criticised. Nonetheless, the same prognostic association has been found in recent series which have been more strictly curated using gross and microscopic pathology, immunohistochemistry and/or patient follow‐up data to confirm primary ovarian origin 63–65 …”

“…70 Based on the prognostic value of the type of invasion in mucinous carcinomas discussed above, Busca et al proposed an alternative grading system based on the presence and amount of infiltrative growth in their study of 52 ovarian mucinous carcinomas. 65 The system classified tumours as low-grade (expansile invasion or infiltrative invasion representing ≤10% of the tumour) and high-grade (infiltrative invasion in >10% of the tumour). This grading correlated with disease-free survival.…”

Outcomes After Fertility-sparing Surgery of Early-stage Ovarian Cancer: a Nationwide Population-based Study

“…also found that grade 3 tumors were an independent poor prognostic factor in terms of PFS 22 . However, it remains controversial whether grade correlates with unfavorable survival outcomes in mucinous carcinomas 23 . Moreover, the grading system for ovarian mucinous carcinomasis globally inconsistent 23 .Busca et al compared two widely used grading systems: the International Federation of Gynecology and Obstetrics (FIGO) system 24 , which was the same grading system used for endometrioid carcinoma, and the Silverberg grading system 25 .…”

“…However, it remains controversial whether grade correlates with unfavorable survival outcomes in mucinous carcinomas 23 . Moreover, the grading system for ovarian mucinous carcinomasis globally inconsistent 23 .Busca et al compared two widely used grading systems: the International Federation of Gynecology and Obstetrics (FIGO) system 24 , which was the same grading system used for endometrioid carcinoma, and the Silverberg grading system 25 . They found that only the Silverberg grading system appeared to correlate with outcome in cases of mucinous carcinoma 23 .…”

“…In Taiwan, there are approximately 1446 new cases ofovarian cancer and 624 deaths from ovarian cancer annually 2 , and the incidence rate keeps raising 3 . At the time of ovarian cancer diagnosis, 23.1% of patients are between 20-45 years of age 2 . These patients are still of reproductive agewhen diagnosed, and may not havecompleted their family planning 4 .…”