Presenter(s)
S. Fattahi1, A. Goodman2, M. A. Dyer3, A. C. Smart3, and A. L. Russo3; 1Harvard Radiation Oncology Program, Boston, MA, 2Department of Gynecologic Oncology, Massachusetts General Hospital, Boston, MA, 3Department of Radiation Oncology, Mass General Brigham Cancer Institute, Boston, MA
Purpose/Objective(s): Endometrial cancer is primarily managed with hysterectomy/BSO/lymph node assessment +/- adjuvant therapy (radiation therapy (RT) and/or chemotherapy) based on pathologic findings. For patients (pts) presenting with surgically inoperable disease, there is no consensus on standard of care management and data is limited. We sought to evaluate the role of preoperative external beam RT (EBRT) +/- high dose rate brachytherapy in pts with stage II or higher surgically inoperable endometrial cancer.
Materials/Methods: This study was IRB approved. Pts with stage II or higher surgically inoperable endometrial cancer planned for preoperative RT followed by hysterectomy between 2003 and 2025 were eligible. Overall survival (OS), disease-specific survival (DSS), and freedom from locoregional recurrence (FLR) were calculated using Kaplan-Meier estimates. Events were calculated from completion of preoperative RT.
Results: We identified 23 pts. Median age at diagnosis was 60.4 years (interquartile range (IQR): 58.3-65.1 years). FIGO 2009 stage was IIIC in 9 pts (39.1%), IIIB in 8 (34.8%), II in 4 (17.4%), IIIA in 1 (4.3%), and IVA in 1 (4.3%). Histology was endometrioid in 19 pts (82.6%), clear cell in 2 (8.7%), serous in 1 (4.3%), and carcinosarcoma in 1 (4.3%). Grade was 3 in 10 pts (43.5%), 1 in 9 (39.1%), and 2 in 4 (17.4%).
With regards to preoperative RT, 20 pts (87.0%) received EBRT + brachytherapy, 2 (8.7%) received brachytherapy only, and 1 (4.3%) received EBRT only. Brachytherapy was tandem and ovoid/ring based. Median EBRT dose was 45 Gy in 25 fractions. Median brachytherapy dose was 20.5 Gy in 3 fractions. Tumor percent decrease was able to be calculated from pre- and post-RT magnetic resonance imaging scans for 15 patients with a median decrease of 57.0% (IQR: 38.5-75.0%). Reason for inoperability was cervical and vaginal invasion in 12 pts (52.2%), cervical only in 10 (43.5%), and vaginal only in 1 (4.3%). Within the cohort, 20 pts (87.0%) were able to proceed with hysterectomy at a median of 3.9 weeks (IQR: 3.0-7.6 weeks) from completion of RT – 1 pt had aborted hysterectomy due to extent of disease, 1 declined hysterectomy at completion of RT, and 1 developed saddle pulmonary embolism and was deemed too high risk to proceed at completion of RT. Complete pathologic response was achieved in 2 pts (8.7%). Postoperative complications within 30 days of surgery occurred in 2 pts (8.7%). Median follow up time was 2.2 years (IQR: 1.6-4.2 years). At 2 years, OS was 90.7% (95% confidence interval (CI): 79.2, 100), DSS was 95.0% (95% CI: 85.9, 100), and FLR was 73.9% (95% CI: 58.0, 94.2).Conclusion: At 2 years, survival outcomes are reassuring in an advanced disease group. FLR is low but not unexpected in a complex group of patients with advanced disease. Larger cohort and longer follow-up time are needed to better understand the efficacy of preoperative EBRT +/- brachytherapy in the treatment of surgically inoperable endometrial cancer.