Aspirin use and survival outcomes in endometrial cancer.

5621 Background: Given the worsening survival trends of endometrial cancer in the United States, further improvement in adjuvant treatment of this cancer is needed. Aspirin use has been shown to reduce cancer risk in multiple cancer types. A randomized controlled trial recently showed that aspirin therapy significantly improved overall survival in patients with colorectal cancer with PIK3CA mutations, a mutation that is seen in up to 50% of endometrial cancers. We therefore hypothesized that aspirin use may similarly improve survival in patients with endometrial cancer. Methods: We conducted a retrospective review of all patients with endometrial cancer treated at a single academic institution between 2014-2017. Demographics, clinicopathologic data, surgical and adjuvant treatment, and aspirin use were collected from the medical record. Proportional variables were compared using Fisher’s exact and Chi-square tests. Continuous variables were compared using t-tests and Mann-Whitney U-tests. Disease-specific survival (DSS, time from diagnosis to death due to cancer) was estimated using Kaplan-Meier plots, with log-rank and Cox proportional hazards analysis used to compare groups. Results: A total of 765 patients were included in the study. Most patients were white (92%), had Stage I disease (79.9%), had endometrioid histology (87.1%), and were mismatch repair (MMR) proficient (74.6%). Of the 765 patients, 243 (31.8%) were taking ASA at the time of their endometrial cancer diagnosis, while 522 (68.2%) were not. Patients taking aspirin at the time of diagnosis were significantly older than those who were not (66.2 vs 59.8, p<0.0001). Otherwise, there was no significant difference in BMI, stage, grade, histology, MMR status, or adjuvant treatment between the two groups. On multivariate analysis, aspirin use at diagnosis was significantly associated with improved DSS (HR 0.27 [0.10-0.64], p=0.0020) after adjusting for age, stage, grade, histology, MMR status, and adjuvant treatment. Conclusions: Aspirin use at the time of endometrial cancer diagnosis was associated with a significant improvement in DSS in our cohort. While retrospective, this data is promising as a potential improvement in therapy for patients with endometrial cancer. Additionally, this intervention would be inexpensive and easily accessible for all patients. Prospective data is needed to further evaluate the effect of aspirin on endometrial cancer outcomes.