Endometrial Cancer of the Uterine Isthmus: A Cohort Study on Clinicopathological Features and Prognosis

The study compared the clinicopathologic characteristics and prognosis of patients with uterine isthmus cancer to those with uterine fundus cancer. The aim was to identify risk variables associated with the prognosis of patients with isthmus cancer.

In the SEER cohort, 584 endometrial cancer patients were included: 91 in the isthmus group and 493 in the fundus group. Data for this retrospective study were collected from the Surveillance, Epidemiology, and End Results (SEER) database and the registry of a provincial hospital. SEER included individuals diagnosed with endometrial cancer between 2000 and 2018. Patients were divided into two groups according to the primary site code for endometrial cancer: Isthmus and fundus. Chi-square tests were used to compare the population characteristics. STROBE Protocol was followed.

Isthmus cancers were younger, more advanced, often non-endometrioid adenocarcinomas, and more likely to receive adjuvant therapy (p < 0.05). The 3-year overall survival rate for isthmus cancer was significantly lower than for fundus cancer (p = 0.016). Uterine isthmus cancer in the hospital cohort accounted for 2.0% (9/455) of the diagnosed endometrial cancers. All patients survived without recurrence or metastasis and were in good physical condition.

The research assessed the prognostic impact of the uterine isthmus and the clinical and pathological features of uterine isthmus cancer, and the associated risk factors affecting prognosis. Uterine isthmus cancer demonstrates a higher stage, a stronger tendency for adjuvant therapy, and a more unfavorable prognosis when compared to fundus carcinoma. The international evidence is diverse on this issue.