Adjuvant High-Dose-Rate Brachytherapy Alone for Stage I/II Endometrial Adenocarcinoma using a 4-Gray versus 6-Gray Fractionation Scheme Marie Lynn Racine, M.D 1 and Akila N. Viswanathan, MD, MPH 1. 1 Department of Radiation Oncology, Brigham and Women's Hospital/Dana-Farber Cancer Institute, Boston, Massachussets, United States, Material and Methods  The characteristics of the patients are presented in Table 1.  The two groups were balanced with regard to median age, FIGO Stage, presence of lymphovascular invasion, and LND status. Slightly more patients in group I had LND but this was not statistically significant.  In the 4-Gy/fx group, with a median follow-up (FU) of 17.3 months (range, ), there were no vaginal recurrences (0/37).  In the 6-Gy/fx group, with a median follow-up of 34.3 months (range, ), there were 2/34 (6%) vaginal recurrences (chi-square p=0.03), diagnosed 3 and 4 months after treatment. Purpose/Objective Conclusion g Adjuvant vaginal brachytherapy (VB) after a total-abdominal hysterectomy (TAH) for Stage I/II (occult) endometrial cancer reduces the risks of local recurrence. However, the optimal dose to be delivered is still under debate. It has recently been suggested that a smaller dose per fraction would help decrease vaginal stenosis rates, mucosal atrophy and vaginal bleeding in a population diagnosed with low-risk endometrial cancer, compared to a higher dose per fraction regimen. After the 2005 publication of a trial from Sorbe showing lower vaginal stenosis rates in patients treated with 6 fractions of 2.5 Gy prescribed at 5 mm, this regimen was modified at BWH/DFCI to 4 Gy/fraction times 6 fractions prescribed at the vaginal surface. The purpose of this study was to assess the risk of vaginal recurrence and compare two high-dose-rate (HDR) dose-fractionation schedules in patients with Stage I/II endometrial adenocarcinoma treated with a total-abdominal hysterectomy with or without lymph node dissection (LND) followed by adjuvant endocavitary vaginal brachytherapy alone.  From 2002 to 2007, 116 patients were treated with a TAH followed by HDR VB at the Brigham and Women’s Hospital.  Of these 116, 29 were excluded because of Stage III disease (6), non- endometrioid pathology (21) or synchronous carcinoma (2).  Seventy-one had full follow-up information available and were included in the analysis.  Between August 2002 and August 2005, 34 patients were treated with 6 Gy times 5 fractions.  Between April 2005 and March 2007, 37 patients were treated with 4 Gy times 6 fractions.  A chi-square test was used to compare the recurrence rates in the two groups. Group I 4 Gray/fraction Group II 6 Gray/fraction Median age 63 (range: 46-81) 68 (range: 48-86) Number of patients (%) Number of patients (%) Status of Nodal dissection Nodal sampling Complete nodal dissection No Nodal dissection Lymphovascular invasion Present Absent 8 (22) 26 (70) 3 (8) 5 (14) 32 (86) 9 (28) 16 (47) 9 (25) 3 (9) 31 (91) FIGO Stage IA IB IC IIA Occult IIB 1 (3) 23 (62) 8 (21) 1 (3) 4 (11) 1 (3) 20 (59) 8 (23) 4 (12) 1 (3) Grade (35) 17 (46) 7 (19) 6 (18) 22 (64) 6 (18)  In this series, 4 Gy/fraction prescribed to the vaginal surface yields an excellent outcome for patients diagnosed with early-stage endometrial adenocarcinoma treated with vaginal brachytherapy only, and is comparable to the higher dose per fraction regimen.  Long-term follow-up is needed in order to further assess the toxicities including vaginal stenosis, and the long term vaginal recurrence rate. Table 1. Characteristics of patients Results