137 RTOG 9708: Adjuvant Postoperative Irradiation Combined with Cisplatin/Taxol Chemotherapy following Surgery for Patients with High-Risk Endometrial Cancer K. M. Greven, 1 K. Winter, 6 K. Underhill, 2 F. James, 3 J. Cooper, 4 T. Burke 5 1 Radiation Oncology , Wake Forest Univ. School of Medicine, Winston Salem, NC, 2 Radiation Oncology, Thomas Jefferson University Hospital, Philadelphia, PA, 3 Radiation Oncology, Wayne State University, Detroit, MI, 4 Radiation Oncology, New York University Hospital Medical Center, New York, NY, 5 Gynecologic Oncology, UT MD Anderson Cancer Center, Houston, TX, 6 Radiation Therapy Oncology Group, Philadelphia, PA Purpose/Objective: Patients with completely resected high-risk endometrial cancer are at risk of disease recurrence even with the addition of adjuvant pelvic radiation. A phase II study was completed by the RTOG to assess the feasibility, safety, toxicity, and patterns of recurrence and survival when chemotherapy was combined with radiation for these patients. This report is an update of the late toxicity and patterns of recurrence and survival. Materials/Methods: Eligibility requirements included total abdominal hysterectomy and bilateral salpingo-oophorectomy no more than 8 weeks prior to radiotherapy that demonstrated grade 2 or 3 endometrial adenocarcinoma with either 50% myometrial invasion, cervical stromal invasion, or pelvic-confined extrauterine disease. This study was designed to administer 4500cGy in 25 fractions to the pelvis along with cisplatin (50mg/M2) on days 1 and 28. Vaginal brachytherapy with low dose rate (1  20Gy to surface) or high dose rate (3  6 Gy to the surface) applicator was performed after the external beam radiation. Four courses of cisplatin (50mg/M2) and Taxol (175mg/M2) were given at 4-week intervals following completion of radiotherapy. Results: Forty-six patients were entered between 10/97 and 4/99. Two patients were considered ineligible (one with a previous bladder cancer and one with surgery more than 8 weeks prior to start of RT). Follow-up times range from 6.9 to 61 months with a median of 4 years. Stage of disease was III, II and I in 61%, 16%, and 23% of patients respectively. Maximum late toxicity was grade 1 in 16%, grade 2 in 39%, grade 3 in 16%, and grade 4 in 5%. At 4 years pelvic, regional and distant recurrence rates are 2%, 2%, 19%, respectively. Six deaths occurred which were all due to recurrent endometrial cancer. Overall survival and disease-free (DFS) rates are 85% and 81% respectively. Four-year rates for survival and DFS for stage III patients are 77% and 72% respectively. There have been no recurrences for patients with stage IC, IIA, or IIB. Conclusions: As previously reported, the treatment protocol demonstrated a satisfactory completion rate and acute toxicity. Late toxicity is also acceptable. Local-regional control is excellent following combined modality treatment in all patients suggesting synergistic effects of chemotherapy and radiation. Distant metastases continue to occur in more advanced stage patients. This regimen appears reasonable to be tested for efficacy in randomized patients. 138 Vaginal Brachytherapy Alone: An Alternative to Whole Pelvis Radiation for Early Stage Endometrial Cancer S. Jolly, 1 T. Kumar, 1 C. Vargas, 1 S. Weiner, 2 D. Brabbins, 1 P. Chen, 1 L. Kestin, 1 W. Floyd, 2 A. Martinez 1 1 Radiation Oncology, William Beaumont Hospital, Royal Oak, MI, 2 Gynecologic Oncology, William Beaumont Hospital, Royal Oak, MI Purpose/Objective: Post-operative management of early stage adenocarcinoma of the endometrium remains controversial. The use of pelvic radiation therapy (RT) as shown by the Gynecologic Oncology Group (GOG) 99 trial improves the event free interval at the cost of increased toxicity. We reviewed and compared our results treating early stage endometrial adenocarci- noma using high dose rate (HDR) vaginal brachytherapy (VB) alone with the results of the GOG 99. Materials/Methods: From 1992 to 2002, 243 endometrial cancer patients were treated with TAH/BSO and selective lymph node dissection followed by adjuvant RT. Of these, 50 FIGO stage I-II(occult) adenocarcinoma (no clear cell or serous papillary) of the endometrium were managed with HDR hypofractionated VB as monotherapy using Iridium-192 to a dose of 30 Gy in 6 fractions twice weekly prescribed to a depth of 5 mm and median length of 4 cm. The characteristics, toxicity rates, and outcomes of our patients were compared with the results of the GOG 99. The median follow up of our patients and GOG 99 were 3.2 years and 5.8 years, respectively. Results: Patients characteristics including age, stage, and grade were similar in our study and the GOG-99 (see table). The local recurrence rate in our study, the pelvic RT arm of the GOG, and the no RT arm of the GOG were 4% (n = 2), 2% (n = 3), and 9% (n = 18), respectively. In our study, one patient failed in the vagina alone and a second patient failed in the vagina and pelvis. In the GOG 99, the vagina as a component of locoregional failure was also the most common failure site in the no RT arm 77.8% (n = 14) and in the RT arm 100% (n = 3). The 2-year cumulative recurrence rate in our study was 2%, which compares favorably with the GOG pelvic RT arm (3%) and observation arm (12%). Four-year survival rates of the no RT arm of the GOG, the RT arm of the GOG, and our study with HDR VB were 86%, 92% and 97%, respectively. Chronic grade 2 toxicity rates were reduced by the use of VB compared to pelvic RT, especially GI toxicity 0% vs. 34% (p-value0.0001), and GI obstruction 0% vs. 7% (p-value = 0.08). Conclusions: Stage I-II(occult) endometrial adenocarcinoma treated with post-operative hypofractionated HDR vaginal brachytherapy has similar overall survival, locoregional failure rates, and cumulative recurrence rates to standard fractionation external beam pelvic RT with the benefit of lower toxicity rates and shorter overall treatment time. S212 I. J. Radiation Oncology ● Biology ● Physics Volume 60, Number 1, Supplement, 2004