ESTRO 2022 - Abstract Book

S809

Abstract book

ESTRO 2022

with non-endometrioid type, mixed histology tumors, or synchronous cancers were excluded. Clinical outcomes (loco- regional disease-free survival [LR-DFS], distant metastasis disease-free survival [DM-DFS], overall survival [OS]) were analyzed using Kaplan-Meier method. Results After surgical staging, 335 patients with pathological LN negative Stage 1 endometrioid-type endometrial carcinoma were identified. Median patient age was 63.9 years. Substantial LVSI was present in 59 patients (17.6%). Majority of patients (50.5%) were observed after surgery, 39.7% received adjuvant vaginal brachytherapy, and 6.9% received both EBRT and vaginal brachytherapy. Adjuvant radiation treatment varied with the three-tiered LSVI scoring system (p<0.01). In patients with no LVSI, the majority of patients were observed (75.1%). In patients with focal LVSI, 81.0% of patients received vaginal brachytherapy. Among patients with substantial LVSI, 57.9% received vaginal brachytherapy, and 31.6% of patients received both vaginal brachytherapy and EBRT. The majority of patients (95.8%) received no chemotherapy. With a median follow- up of 25.7 months, the 2-year LR-DFS rates were 92.5%, 98.0%, and 92.7% for no LVSI, focal LVSI, and substantial LVSI, respectively. For DM-DFS, 2-year rates were 95.5%, 93.3%, and 93.8% for no LVSI, focal LVSI, and substantial LVSI, respectively. The 2-year rates for OS were 97.6%, 98.1%, and 98.2% for no LVSI, focal LVSI, and substantial LVSI, respectively. Conclusion In our single institution study, patients with pathological LN negative stage I endometrioid-type endometrial cancer with substantial LVSI have similar rates of LR-DFS, DM-DFS, and OS compared to patients with none/focal LVSI. Compared to the PORTEC findings, these findings suggest the need for additional multi-institutional studies to confirm the prognostic value of substantial LVSI in this patient cohort. S.L. Villa 1 , A. Fodor 1 , G. Mandurino 1 , F. Zerbetto 1 , C.L. Deantoni 1 , A. Sanchez Galvan 2 , R. Tummineri 1 , S. Baroni 1 , J. Saddi 1 , P. Mangili 3 , R. Castriconi 3 , S. Arcangeli 4 , N.G. Di Muzio 1,5 1 IRCCS San Raffaele Scientific Institute, Radiotherapy, Milan, Italy; 2 IRCCS San Raffaele Scientific Institute, Radiotherapy, Milano, Italy; 3 IRCCS San Raffaele Scientific Institute, Medical Physics, Milan, Italy; 4 University of "Milano-Bicocca", Radiotherapy, Milan, Italy; 5 “Vita-Salute San Raffaele” University, Radiotherapy, Milan, Italy Purpose or Objective To compare outcomes and toxicity of salvage extended nodal radiotherapy (ENRT) versus Stereotactic body radiotherapy (SBRT) on lymph nodal (LN) relapse in oligometastatic gynecological cancer patients (pts). Materials and Methods From 03/2007 to 10/2021, 53 gynecological cancer patients with LN relapse after previous radical therapies were treated with fluoro-deoxy-glucose positron emission tomography/computed tomography (PET/CT) guided-salvage RT in our Institution: 28 with ENRT+SiB on positive PET/TC LN (group 1) and 25 with SBRT (group 2) on positive PET/TC LN. Primary histology was: ovarian in 20pts, endometrial in 18pts, cervix in 11pts and others in 3pts, almost equally distributed in the two groups. In group 1 two target were defined: the first one included the lymph-nodal chain of interest (pelvic, para- aortic or mediastinal) as clinical target volume (CTV1), adding a 7mm isometric margin to obtain the planning target volume (PTV1). The PTV2 was obtained adding a 5mm isometric margin to GTV-PET. In group 2 the PTV was obtained adding 3 mm isometric margin to GTV-PET. The prescription dose was 50.4Gy/28 fractions (fr) to PTV1 and median dose of 61.01 (50.4- 65.5)Gy to PTV2 in group 1, while in group 2 the median dose to PTV was 36 (30-45)Gy in 3-5 fr (6-12Gy/fr). The treatment was delivered with TomoTherapy® or RapidArc® (Varian Medical Systems, Palo Alto, CA) in group 1 and CyberKnife®(Accuray, Sunnyvale, CA) in group 2. Results Median follow-up was 32.2 (3.4 – 142.4) and 14.67 (3.2-39.11) months for group 1 and 2, respectively. Acute toxicity were almost negligible in SBRT and mild, in the ENRT group, (see table 1). Loco-regional relapse was registered in 4/28 pts in group 1, while in group 2 relapse in lymph-nodal chain was registered in and 2/25 pts and no recurrence occurred in the single lymph-node treated with SBRT. Systemic progression was observed in 50% of pts in both group (53% vs 48%). Kaplan Meier estimates of 12 months OS were 88% vs 93% (p=0,21), while 12-months DFS was 54 vs 58 % (p=0,99). PD-0914 SBRT versus ENRT in oligometastatic gynaecologic tumors: techniques comparison.