Objective: Postoperative management of early stage adenocarcinoma of the endometrium remains controversial. The use of pelvic radiation therapy 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 adenocarcinoma using hypofractionated high dose rate (HDR) vaginal brachytherapy (VB) alone with the results of the GOG-99.
Methods: From 1992 to 2002, 243 endometrial cancer patients were treated with TAH/BSO and selective lymph node dissection followed by adjuvant radiotherapy (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 the GOG-99 were 3.2 years and 5.8 years, respectively.
Results: Patient characteristics including age, stage, and grade were similar in our study and the GOG-99. The local recurrence rate in our study, the pelvic RT arm of the GOG-99, and the no RT arm of the GOG-99 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-99 pelvic RT arm (3%) and observation arm (12%). Four-year survival rates of the no RT arm of the GOG-99, the RT arm of the GOG-99, 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 < 0.001), and GI obstruction 0% vs. 7% (P value = 0.08).
Conclusion: Stage I-II (occult) endometrial adenocarcinoma treated with postoperative 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 much lower toxicity rates and shorter overall treatment time.