3503 - The Role of Adjuvant Radiotherapy and Chemotherapy for Surgically Staged Non-Myoinvasive Uterine Serous Carcinoma with Negative Peritoneal Washings

A. I. Ghanem^1,2, I. Aref³, C. H. Lin⁴, R. Khalil-Moawad⁵, M. Elshaikh⁵, and M. A. Elshaikh³; ¹Department of Radiation Oncology, Henry Ford Health, Detroit, MI, ²Alexandria Clinical Oncology Department, Alexandria University, Alexandria, Egypt, ³Department of Radiation Oncology, Henry Ford Cancer Institute, Detroit, MI, ⁴Department of Public Health Sciences, Henry Ford Health, Detroit, MI, ⁵Department of Radiation Oncology, Henry Ford Health-Cancer, Detroit, MI

Purpose/Objective(s): Uterine serous cell adenocarcinoma (USC) represents an aggressive subtype of uterine carcinoma with poor survival especially if peritoneal washings have positive cytology. However, patients with stage I non-myoinvasive USC carry a better prognosis with controversial role for adjuvant therapies. We evaluated the survival impact of various adjuvant approaches for women with non-myoinvasive USC who had negative peritoneal washings. Materials/

Methods: We queried our uterine cancer database for patients with 2009 FIGO stage I non-myoinvasive USC who underwent hysterectomy with negative peritoneal washings at our institution between 1/1990-1/2023. Patients with synchronous malignancies and those with positive peritoneal cytology were excluded. We compared clinicopathological characteristics as well as survival endpoints using Kaplan-Meier curves and log-rank test based on patients’ receipt of any adjuvant treatment.
Results: Eighty-nine patients were included with a median age (interquartile range (IQR)) of 66 (62-72) years and a median (IQR) follow-up of 6.9 (5.9-9.2) years. The disease was confined to a polyp in 40% and 5.6% had lymphovascular space invasion. Omentectomy, pelvic and paraaortic lymph node (LN) surgical evaluation were performed in 65%, 84% and 43% of patients, respectively; with a median (IQR) retrieved LNs of 9 (2-22). 44 patients (49.4%) received adjuvant treatment: 27% radiation therapy (RT) plus chemotherapy (CT), 10% RT alone and 12.4% CT alone; and 45 patients (50.6%) were managed with surveillance. RT modalities utilized were vaginal cuff brachytherapy in 24/33, pelvic external beam RT in 4/33 and 5/33 received a combination. CT was 4-6 cycles of carboplatin and paclitaxel, whereas surveillance encompassed regular follow-up visits with examination, imaging and biopsies as needed. Surveillance patients were older than adjuvant therapies recipients: median (IQR) age 68 (63-74) vs 65 (60-68), respectively (P=0.01). Eleven patients (12.4%) were diagnosed with disease recurrence mainly distant. For patients who were managed with surveillance, compared to those who received adjuvant therapies, there was no statistically significant difference in 5-year recurrence-free (RFS) (78.2% (95% confidence interval (CI):65.8-93.1) vs 91.4% (CI: 82.5-100); P=0.08), disease-specific (DSS) (85.4% (74.4-98.2) vs 97% (91.3-100); P=0.1) and overall (OS) (83.3% (CI: 71.9-96.5) vs 92.1% (CI: 84-100); P=0.46) survival, respectively. The site of first recurrence pattern was non-different across both groups. On multivariate analyses, Charlson comorbidity burden independently predicted worse RFS (P=0.011) and OS (P=0.039), whereas tumor confined to polyp was associated with better RFS (P=0.043) and DSS (P=0.05).
Conclusion: For surgically staged patients with non-myoinvasive USC, and negative peritoneal washings, our study suggests that surveillance is a viable adjuvant option and should be discussed with similar patients, especially older ones.