Clinicopathologic Characteristics, Molecular Profile, Treatment, and Recurrence in Endometrial Cancer with Pelvic Lymph Node Isolated Tumor Cells

Objective: Our objective was to characterize the molecular–pathologic profile and recurrence patterns of endometrial cancer with pelvic lymph node isolated tumor cells (ITCs). Methods: A single-center retrospective study of patients with endometrial cancer and ITCs was conducted. Patients with concurrent lymph nodes or distant metastasis were excluded. Cases were reviewed by a gynecologic pathologist, and electronic medical records were reviewed. Descriptive statistics were performed using R 4.4.2. Results: A total of 43 patients were included, with a median follow-up time of 33 months. The majority were endometrioid carcinoma (91%) and stage I (72%). In total, 28 (65%) were MMR-proficient and p53-wild-type (MMRp p53wt), nine (21%) were MMR-deficient (MMRd), six (14%) were p53-abnormal (p53abn), and none were POLE-mutated (POLEmut). Additionally, 27 (96%) MMRp p53wt cases showed a microcystic, elongated, and fragmented (MELF) pattern of invasion. Adjuvant therapy was indicated in 38 (88%) patients; 32 (74%) received therapy and six (14%) declined. Four (9.3%) patients recurred, with a recurrence rate of 33% (2/6) for p53abn, 11% (1/9) for MMRd, and 4% (1/28) for MMRp p53wt. All recurrences were to distant sites. In the MMRp p53wt group, 16 (57%) had external beam radiation (EBRT) +/− vaginal brachytherapy (VBT), three (11%) had chemotherapy +/− radiation, and nine (32%) had no adjuvant treatment or VBT alone. Conclusions: Molecular profile is prognostically relevant in endometrial carcinoma with ITCs. ITCs in MMRp p53wt endometrioid carcinoma present a low risk of disease recurrence. As the majority of our cohort received adjuvant therapy, future work may explore de-escalating treatment in low-risk ITC cases.