Materials/Methods: After institutional review board-approval, 388 women with FIGO stage I-II uterine endometrioid carcinoma were included in this study. 194 women who had received adjuvant radiation treatment (RT) were exactly matched with 194 women who were observed after hyster- ectomy (1:1 match, strictly based on FIGO stage and grade). AACCI score at time of hysterectomy was determined by trained physicians based on review of all available medical records. Based on AACCI, the study cohort was divided into those with AACCI score of 0 (healthier) vs. those with a score of 1. Univariate and multivariate modeling with Cox regression analysis was used to determine significant predictors of recurrence-free (RFS), disease-specific (DSS) and overall survival (OS). Results: Median follow-up for the study cohort was 58 months. While women who received adjuvant RT had a significantly higher 5-year RFS (90% vs. 78%, pZ0.002), there was no significant difference in 5-year OS (88% vs. 86%, pZ0.589). When accounting for comorbidity burden in women who received RT, 5-year OS was (94% vs. 81%, pZ0.017) for women with AACCI score of 0 compared to those with a score of > 1, with an absolute difference of 13% at 5-year and 23% at 10 year OS. Similarly, for those who were observed after hysterectomy, 5-year OS was 91% vs 80%, pZ0.011. The impact of AACCI was not statistically significant on 5-year RFS and DSS. On multivariate analyses for the entire cohort, higher AACCI score, older age, tumor grade (3 vs 1), and lymphovascular space invasion (LVSI) were significantly independent predictors for shorter OS. LVSI and grade 3 were the only two independent predictors of DSS. The lack of adjuvant RT and the presence of LVSI were significant predictors of worse RFS. Conclusion: Comorbidity burden is just as important as traditional prog- nostic variables for predicting overall survival in women with early-stage endometrioid endometrial carcinoma. Its prognostic impact should be accounted for in future prospective studies of women with endometrial cancer. On the other hand, its prognostic impact was not observed for RFS and DSS. Author Disclosure: D.M. Bergman: None. S. Chaugle: None. C. Bur- meister: None. R.K. Hanna: None. M.A. Elshaikh: None. TU_19_3506 Vaginal Cuff Treatment and Subsequent Quality of Life Related Recommendations in Radiation Oncology Practice: Turkish Oncology Group Study Survey Report Y. Bolukbasi, 1 , 2 F. Yildiz, 3 Z. Ozsaran, 4 C. Onal, 5 D. Sezen, 1 and U. Selek 1,2 ; 1 Koc University, School of Medicine, Department of Radiation Oncology, Istanbul, Turkey, 2 MD Anderson Radiation Oncology Outreach Center at American Hospital, Istanbul, Turkey, 3 Hacettepe University, School of Medicine, Department of Radiation Oncology, Ankara, Turkey, 4 Ege University, School of Medicine, Department of Radiation Oncology, Izmir, Turkey, 5 Baskent University, School of Medicine, Department of Radiation Oncology, Adana, Turkey Purpose/Objective(s): The American Brachytherapy Association is attempting to develop standards but the differences in practice are also emphasized in the literature. The aim of this study was to evaluate the approach to vaginal cuff treatment practice and subsequent quality of life related recommendations of Turkish Radiation Oncologists. Materials/Methods: A nationwide web-based survey with 16 focused items, was distributed to the members of Turkish Society for Radiation Oncology (TSRO) through email notification & posted link on TSRO website to respond on a volunteer basis from January 2 nd to February 12 th , 2018. The time required to complete the survey was approximately 4 minutes. Results: A total of 54 Radiation Oncologists answered the survey. The most commonly used dose fraction schemes were 7 Gy x 3 fractions (29,6%), 5.5 Gy x 5 fractions (27.7%) and 6 Gy x 5 fractions (25.9%) for adjuvant vaginal cuff brachytherapy. The preferred schema for vaginal cuff brachytherapy in combination with external radiotherapy (45 Gy), were 5 Gy x 3 fractions (50.9%) and 6 Gy x 3 fractions (33.9%). The application dose was frequently modified as 6 Gy x 3 fractions (28.3%) or 5 Gy x 3 fractions (33,9%) when the external radiotherapy dose was increased to 50.4 Gy. Half of the participants, applied brachytherapy as 2 fractions per week and the common approach was prescribing the dose to 0.5 cm from the mucosa (86.7%). Foley catheter was usually applied for every fraction by 46.3% while 35.1% did not suggest its use. Bowel preparation was recommended for every application by 51.8 % of the participating radia- tion oncologists. CT-based planning for the first fraction was performed by 68.5% while 12.9% did not use CT-based planning. There was no common definition for dose prescription length; 33% of the survey responders preferred defining it as the first 3 cm, 37% as the first 4 cm, 11% as the whole cylinder and the rest as a third of the vaginal length. The dose prescription for the serous and clear cell histological types, 40% of the participants advised "full cylinder length" as target and the dose preference was similar to the conventional dose schemas for adenocancer. The per- centage of those who recommended a dilator or intercourse after treatment was 79.2%. Conclusion: The survey results revealed that approaches to the clinical practice of vaginal cuff brachytherapy varies although it deemed to be a simple intervention. Author Disclosure: Y. Bolukbasi: None. F. Yildiz: None. Z. Ozsaran: None. C. Onal: None. D. Sezen: None. U. Selek: General Secretary & International Relationships Council Member; Turkish Society of Lung Cancer. International Relationships Council Member, Education Council Member; Turkish Society for Radiation Oncology. TU_19_3507 Prognostic Importance of Distant Metastatic Disease Sites in Endometrial Cancer: A Population-Based Study of 4577 Patients J. Budnik, 1 M.D. Stolten, 1 M.T. Milano, 2 and K.C. Bylund 1 ; 1 Department of Radiation Oncology, University of Rochester Medical Center, Rochester, NY, 2 University of Rochester Medical Center, Rochester, NY Purpose/Objective(s): The majority of women diagnosed with endome- trial cancer have early stage disease which has an excellent prognosis with definitive treatment. However, endometrial cancers also readily metasta- size to distant sites and therapeutic options for metastatic patients remain limited. To date, few population-based studies have examined the impact of distant metastatic disease sites on the survival of endometrial cancer patients. We aimed to investigate this using the Surveillance, Epidemi- ology, and End Results (SEER) database. Materials/Methods: We included 4577 patients from the SEER database diagnosed with metastatic endometrial cancer from 2010-2014. We then identified those patients coded as having metastatic disease in bone, brain, liver, and lung. Kaplan-Meier analyses, log-rank tests, and both univariate and multivariate Cox proportional hazards models were used to examine the impact of metastatic disease sites on overall survival (OS). Results: Most patients in the cohort were white (nZ3304, 72.2%). Median age at diagnosis was 65 years and median OS was 14 months. Endome- trioid (nZ1301, 28.4%), serous (nZ971, 21.2%) and carcinosarcoma (nZ749, 16.4%) histologies were the most common. The majority of patients (nZ2767, 60.5%) had no documented metastases in the bone, brain, liver, or lung (“M1NOS-group”), likely reflecting pelvic-abdominal metastases not captured in the SEER registries. With Cox regression ac- counting for age at diagnosis, race, histology, grade, T stage, and N stage, patients coded as harboring extra-abdominal/pelvic metastatic disease in only the bone (HRZ1.82, p<0.001), brain (HRZ2.93, p<0.001), liver (HRZ1.50, p<0.001), or lung (HRZ1.50, p<0.001) had poorer OS relative to those in the M1NOS-group. Likewise, patients coded as harboring multiple extra-abdominal/pelvic sites of metastatic disease had poorer OS relative to the M1NOS-group (p<0.001). Black race (HRZ1.29, p<0.001), and carcinosarcoma histology (HRZ1.54, p<0.001) were also associated with poorer OS on multivariate analysis relative to white patients and endometrioid histology respectively. Conclusion: This hypothesis-generating study suggests that the prognosis of patients diagnosed with metastatic endometrial cancer not located in bone, brain, liver, or lung is improved relative to those harboring disease in any one, or a combination of these sites. This may inform future International Journal of Radiation Oncology  Biology  Physics E644