ESTRO 2023 - Abstract Book

S1143

Digital Posters

ESTRO 2023

Conclusion Survival in patients with high risk to have positive margin at final pathology after radical surgery alone showing particularly dismal survival rates. IORT is a viable option during pelvic exenteration for recurrent or persistent gynecological cancer still, with limited data, that might be considered to consolidate areas at high risk of relapse due to close or microscopically positive margins. Whether IORT can improve local recurrence rates will require further prospective investigation.

PO-1414 Adjuvant radiotherapy in endometrioid carcinoma with MELF pattern: a single-center experience

A. Nardangeli 1 , R. Autorino 1 , S. Di Franco 1 , R. Rinaldi 1 , M. Campitelli 1 , V. De Luca 1 , S. Lucci 1 , V. Lancellotta 1 , G. Macchia 2 , G. Ferrandina 3 , M.A. Gambacorta 1 1 Fondazione Policlinico Universitario A. Gemelli IRCCS, UOC Radioterapia Oncologica, Rome, Italy; 2 Molise Hospital, Unità Operativa di Radioterapia, Campobasso, Italy; 3 Fondazione Policlinico Universitario A. Gemelli IRCCS, Woman, Child and Public Health Department, , Rome, Italy Purpose or Objective Microcystic, elongated, fragmented (MELF) pattern of myometrial invasion has been proposed as a prognostic marker in patients with endometrial carcinoma (EC). Its prognostic and predictive effect still remains unclear. Aim of this study was to analyze the association of MELF pattern invasion with clinical pathology data and prognosis of the patients with MELF endometrial cancer treated by adjuvant external beam radiotherapy followed by brachytherapy boost. Materials and Methods Patients (pts) affected by endometrial cancer with microcystic, elongated, fragmented (MELF) pattern of myometrial invasion treated in our Institution between January 2017 and September 2021 were retrospectively enrolled in this study. All patients underwent total hysterectomy, bilateral adnexectomy and pelvic dissection followed by adjuvant radiotherapy. Adjuvant external beam radiotherapy was delivered to the pelvis with Volumetric Modulated Arc Therapy (VMAT) strategy for a total dose of 45 Gy, 1.8 Gy/fraction plus a brachytherapy boost on vaginal cuff for a total dose of 10Gy in 2 fraction weekly. When indicated, adjuvant platin-based chemotherapy was administered before the begin of radiotherapy. Results The clinico-pathological data of 39 pts (median age: 55 years; 2018 FIGO Stage IA: 5; IB: 10; II: 4; IIIA: 1; IIIC1: 19 ) were retrospectively analyze. Lymphovascular space invasion (LVSI) was described in 26 pts (66.6%), with focal LVSI in 5 pts and substantial LVSI in 21 pts. Median follow up was 24 months (range 8-64). Only one patient developed distant metastases 30 months after surgery. Median LC was 46 months; 2-ys and 4-ys LC and OS were of 95%. No correlation was found with type of surgery, number of removed and positive pelvic nodes and LVSI. The treatment was well tolerated with only one patient who developed a grade 2 gastrointestinal toxicity. Conclusion MELF appears to be one of the most aggressive patterns of myometrial invasion in endometrioid adenocarcinoma. The lack of international guidelines makes the management of this type of pattern controversial. In our experience, MELF endometrioid adenocarcinomas can be treated with adjuvant external beam radiotherapy, regardless of disease stage, with good results and acceptable toxicity.