Objective  To investigate the expression levels and mutation status of phosphatidylinositol-4, 5-bisphosphate3-kinase catalytic subunit alpha (PIK3CA) in endometrial cancer (EC) and evaluate its association with lymph node metastasis in EC.

Methods We retrosepctively collected and analyzed EC genetic mutation testing data submitted to the Molecular Detection Center, The First Affiliated Hospital of Chongqing Medical University between July 2020 and June 2022. The mutation rate of PIK3CA gene was calculated based on the sequencing results of EC patients, and the correlation between PIK3CA mutations and clinical pathological parameters, as well as protein expression consistency, was analyzed accordingly.

Results  A total of 97 EC patients were enrolled in this study, and PIK3CA mutations were identified in approximately 48.5% (47 out of 97 cases). The rate of lymph node metastasis in patients with PIK3CA mutations was higher than that in patients with wild-type PIK3CA (21.3% vs. 6.0%, P = 0.027). Findings from univariate and multivariate logistic analyses indicated that histological subtype Ⅱ (odds ratio OR = 5.51; 95% CI, 1.08-28.06; P = 0.040), positive result for lymphovascular space invasion (LVSI) (OR = 7.96; 95% CI, 1.37-46.44; P = 0.021), and PIK3CA mutation (OR = 8.58; 95% CI, 1.51-48.84; P = 0.015) were independent risk factors for lymph node metastasis in EC. In addition, the receiver-operating characteristic (ROC) curves demonstrated that the combined use of clinicopathological parameters and PIK3CA mutations could more accurately predict lymph node metastasis in EC, with an area under the curve of 0.824 (95% CI, 0.678-0.970). It is noteworthy that there was a high consistency between PIK3CA mutations and its protein expression, and EC patients with positive expression of PIK3CA protein had a higher rate of lymph node metastasis (53.8% vs. 9.1%, P = 0.078).

Conclusion  PIK3CA somatic mutations are strongly correlated with lymph node metastasis in EC.