Objective: To differentiate endocervical adenocarcinoma (ECA) from endometrial adenocarcinoma (EMA) using p16INK4a, p21WAF1 and p27Kip1.
Study design: The distinction between ECA and EMA can be problematic on small biopsies or in advanced tumor stage. Immunohistochemistry was done on paraffin-embedded tissue sections of hysterectomy specimens of all types of ECA and EMA. Protein expression was scored as 0 to 3 depending on percentage of positive tumor cells.
Results: A total of 40 ECA and 92 EMA cases were examined. For ECA, 32 of 40 (80.0%) cases had score of 3 with p16INK4a expressions; 23 of 92 (25.0%) cases of EMA had similar scores. For p21WAF1 expressions, 28 of 40 (70.0%) ECA cases scored 3 and 72 of 82 (78.2%) of EMA had a similar score. p27Kip1 scored 3 in 17 of 40 (42.5%) ECA cases; only 14 of 92 (15.2%) cases of EMA cases had such a score. We observed significant higher expressions of p16INK4a (p < 0.001) and p27Kip1 (p = 0.001) in ECA than in EMA. Combined positive expression and combined negative expression of p16INK4a and p27Kip1 strongly differentiates ECA from EMA (< 0.0001).
Conclusion: ECA could be strongly differentiated from EMA based on the expressions of combined p16INK4a and p27Kip1.