Hormonal therapy, chemotherapy, or observation for early- stage, low-grade endometrial cancer with malignant peritoneal cytology: A comparative effectiveness study (316)

Abstract

<b>Objectives:</b> Since 2009, peritoneal cytology is no longer required for FIGO surgical staging of endometrial cancer. However, guidelines continue to recommend its collection for assistance with postoperative risk stratification, despite not providing treatment guidelines in the case of positive cytology. We thus sought to examine trends, characteristics, and outcomes related to hormonal therapy (HT) or chemotherapy (CT) use for early-stage, low-grade endometrial cancer with malignant peritoneal cytology (MPC). <b>Methods:</b> A comparative effectiveness study querying the National Cancer Database from 2010-2017 was performed. The study population included 2,730 women with stage I, grade 1-2 endometrioid endometrial cancer who had MPC at primary hysterectomy. Exposure allocation was postoperative therapy: none (<i>n</i>=2,270, 83.2%), CT (<i>n</i>=348, 12.7%), and HT (<i>n</i>=112, 4.1%). The main outcome measures were <i>(i)</i> trends and characteristics related to adjuvant therapy, assessed with a multivariable logistic regression model, and <i>(ii)</i> overall survival (OS) assessed with a multivariable Cox proportional hazards regression model. A sensitivity analysis was performed limited to low-risk endometrial cancer (stage IA, grade 1-2 tumors, and no LVSI). <b>Results:</b> The number of women who received HT (2.7% to 4.5%) or no adjuvant therapy (81.8% to 84.4%) increased while those who received CT decreased (15.5% to 11.1%) over the course of the study period (p=0.04). In a multivariable analysis, HT use was associated with older age, more recent year of diagnosis, grade 1 lesions, treatment at academic/research facilities, the performance of minimally invasive surgery, no LVSI, and absence of radiotherapy compared to CT use (all, p<0.05). The median follow-up was 4.0-4.5 years, and neither HT use (adjusted-HR: 0.61, 95% CI: 0.27-1.40) nor CT use (aHR 1.33, 95% CI: 0.92-1.93) was associated with OS compared to no adjuvant therapy in a multivariable analysis. In the low-risk group (<i>n</i>=1,453), 69 (4.7%) women received HT and 117 (8.1%) received CT. OS was similar across the three groups (p=0.89). <b>Conclusions:</b> There has been an increasing utilization of HT and decreasing utilization of CT as adjuvant therapy for early-stage, low-grade endometrial cancer with MPC over time. These two adjuvant therapies are not associated with short-term OS compared to observation.