The prognostic value of squamous differentiation in endometrioid type endometrial cancer: a matched analysis

We aimed to examine the effect of the squamous differentiation on survival outcomes of women with endometrioid adenocarcinoma. We retrospectively reviewed the patients with endometrioid adenocarcinoma who underwent primary surgical treatment in a tertiary referral hospital. Sixty-nine patients having squamous differentiation constituted the case group. Each woman in the case group was matched with two patients in the control group based on age, disease stage, tumour grade, lymphovascular space invasion, tumour size, myometrial invasion, type of surgery and adjuvant therapy. During the follow-up, the recurrence rates were similar between the case (5/69, 7.2%) and control (10/138, 7.2%) groups (p = 1.0). The 5-year disease-free survival rate was 90.2% for the case group and 88.6% for the control group (p = .51). The 5-year overall survival rate was 94.6% for the case group and 91.8% for the control group (p = .12). Squamous differentiation seems to have no impact on the prognosis of patients with endometrioid adenocarcinoma.IMPACT STATEMENTWhat is already known on this subject? A focus of squamous differentiation is recognised in 12.8-25% of women with endometrioid adenocarcinoma. The prognostic value of the squamous differentiation was evaluated in several previous studies. However, it could not be clarified due to the conflicting results of these studies.What do the results of this study add? The probable confounding effects of well-known prognostic factors including age at diagnosis, International Federation of Gynaecology and Obstetrics stage, tumour grade, lymphovascular space invasion, tumour size, myometrial invasion, type of surgery and adjuvant therapy were eliminated with the case-control study design in the current study. Our findings indicate that the presence of squamous differentiation does not have any prognostic effect in endometrioid type endometrial cancer.What are the implications of these findings for clinical practice and/or further research? The molecular prognosticators of endometrial cancer were extensively studied in recent years. It is likely that clinicopathological and molecular prognostic factors will be integrated for predicting prognosis as a part of routine clinical practice soon. In this context, the prognostic value of the squamous differentiation in endometrioid adenocarcinomas may further be clarified by larger and multicentric studies that utilise central pathology review.