Clinical and Prognostic Value of the Presence of Irregular Giant Nuclear Cells in pT1 Ovarian Clear Cell Carcinoma

In the early stages of epithelial ovarian cancer, histopathological grading is important. However, the grading of ovarian clear cell carcinoma (OCCC) remains controversial. We aimed to identify irregular giant nuclear cells (IGNCs) by a simple method in clinical practice, and to evaluate the prognostic value of IGNCs in pT1 OCCC. Eighty-seven pT1 OCCC patients who underwent initial surgery at Jikei University Kashiwa Hospital, Chiba, Japan, were retrospectively assessed. Paraffin-embedded tissue sections (PTSs) stained with hematoxylin and eosin were reviewed. Giant nuclear cells (GNCs) were defined as cells with a nuclear length of more than twice the median nuclear length. GNCs with irregular nuclear circumferences were defined as IGNCs. Cases where one or more GNCs existed and where IGNCs accounted for >10% of the GNCs were classified as IGNC-positive. We also attempted to identify IGNCs on touch imprint cytology smears (TICSs). Among the 87 cases, 68 were IGNC-negative and 19 were IGNC-positive. The 5-year disease-free and overall survival rates were 88.9% and 90.3% in the total patients, 98.3% and 100% in the IGNC-negative group, and 59.7% and 62.0% in the IGNC-positive group, respectively. These survival rates were significantly lower in the IGNC-positive group than in the IGNC-negative group (adjusted hazard ratio = 14, 95% confidence interval = 2.7–124 and adjusted hazard ratio = 25, 95% confidence interval = 2.9–768, respectively). Prognostic differences were not identified for other factors. IGNC identification on 28 available TICSs predicted IGNC identification on PTSs (sensitivity = 50.0%, specificity = 100%, P = 0.007). The presence of IGNCs has clinical and prognostic value for pT1 OCCC.