Examining the relationship between cesarean section scar and endometrial cancer.

OBJECTIVE

The incidence of endometrial cancer (EC) has been increasing annually. Studies have reported that cesarean section (CS) is associated with a higher risk of developing EC than vaginal delivery (VD). However, few studies have examined the relationship between CS and EC development.

METHODS

Data were extracted from the medical records of patients with EC and a history of childbirth who underwent EC treatment at 3 institutions. Factors contributing to EC development were analyzed between April 2010 and December 2024.

RESULTS

Among patients EC and a history of childbirth, 8.7% (69/794) had undergone CS, and 50.7% (35/69) developed a CS scar. Compared with patients who had a VD or those without a CS scar, patients with a CS scar showed significantly shorter intervals from delivery to EC onset (VD: p=0.013; non-CS scar: p=0.031). A narrower residual myometrial thickness/adjacent myometrial thickness (RMT/AMT) ratio of the CS scar was significantly associated with a shorter interval from the last delivery to EC onset (p=0.034) and was independently associated with earlier EC onset after the last delivery in both univariate and multivariate analyses (p<0.001 and p=0.030, respectively).

CONCLUSION

A narrower RMT/AMT ratio in the CS scar was considerably associated with a shorter interval from the last delivery to EC onset.