The high case-fatality of epithelial ovarian cancer (EOC) stems from the absence of recognisable premalignant lesion, lack of effective screening, advanced stage at presentation, high recurrence and COX-2 over-expression. Expression of COX-2 in EOCs is associated with unfavorable survival outcomes. In Nigeria, younger age affectation, rising incidence and poor survival outcomes of EOC provide the driving forces for researchers in terms of screening, prevention and targeted therapy.

Methods: All the 52 EOC cases over a 5-year period were included, but only 48 formalin-fixed paraffin-embedded tissue blocks were sectioned and stained with COX-2 antibody. COX-2 expression was scored for distribution (no cells = 0, 1%–10% = 1, 11%–50% = 2, 51%–80% = 3, 81%–100% = 4) and intensity (no stain = 0; weak = 1; moderate = 2, strong = 3). The immunoreactive score (IRS) is a product of intensity (I) and distribution (D) as: 9–12 strongly +, 5–8 moderately +, 1–4 weakly + and 0 negative. Over-expression of COX-2 is an IRS of 5–12. Outcomes were statistically evaluated with clinicopathological data.

Results: EOC cases have a mean age of 50.0 years, and peaked in the 6th decade. High-grade serous carcinoma (HGSC) accounted for the majority (50%), followed by low-grade serous carcinoma and mucinous carcinomas each at 17.3%. High-grade carcinomas accounted for 61.5% of cases. Over-expression of COX-2 was observed in 52.1% of the cases with significant associations between COX-2 expression and high-grade EOC, type II EOC or HGSC but not with the other histological sub-type or age.

Conclusion: More than one-third of EOCs occurred ≤50 years and more than half of EOCs over-expressed COX-2. There were significant statistical associations between COX-2 over-expression and grade, type II tumours or HGSC indicating that it may influence the outcomes of EOC with possible variation in tumour type and grade.