ESTRO 2023 - Abstract Book

S1142

Digital Posters

ESTRO 2023

We retrospectively analyzed all patients with histologically diagnosis of LACC, from 2010 to 2020 who had undergone FDG PET and MRI at baseline, treated with radio-chemotherapy plus brachytherapy. Clinical and laboratory variables considered at baseline were age, FIGO stage, grading, HPV status, inflammation markers and RT dose.

We considered several parameters at MRI, ceCT and [18F]FDG-PET/CT. All variables were included in the univariate and multivariate analysis.

Results We included sixty patients, mean age was 59.2±13.1 (range 37-90).

At univariate analysis, FIGO stages III-IVA (HR 11.324, 95% CI 3.076-41.687; p<0.0001), the presence of metastatic para aortic lymph nodes (N) at c.e.CT (HR 3. 608, 95% CI 1.090-11.941; p 0.036) and involvement of more than 10 pelvic N at MRI (HR 9.965, 95% CI 1.202-82.608; p 0.033) were significant predictors of OS. Among the [18F]FDG-PET/CT parameters, MTV of primary lesion (HR 1.022, 95% CI 1.002-1.043; p 0.033), MTV of N (HR 1.009, 95% CI 1.002-1.016; p 0. 015) and TLG (HR 1.002, 95% CI 1.000-1.003; p 0.033), and the presence of FDG-positive para-aortic N (HR 22.942, 95% CI 4.610-114.175; p<0.0001) obtained significance. Multivariate analysis confirmed only FIGO stages III-IVA and the presence of metastatic lymph nodes at [18F]FDG-PET/CT as independent predictors of OS (p 0.003 and p 0.005, respectively). At Kaplan Meier analysis, patients grouped according to FIGO stage showed significantly different OS. Specifically, the median OS of stage III and IVA patients was 61 months (95% CI 9,998-112,002), while stage II patients had a median OS of 120 months (95% CI 120,000-120,000; p<0.0001). A similar result was obtained by grouping the sample according to the presence or absence of FDG-active para-aortic N. The former group showed a median OS of 25 months (95% CI 0.000 51.891), while patients without metastatic N at [18F]FDG-PET/CT presented a median OS of 120 months (95% CI 120.000 120.000; p<0.0001). Combining the two parameters distinguished three classes of patients with significantly different OS (p<0.0001). The group with both predictors had a median OS of 13 months (95% CI 10,434-15,566), patients with only one of the two risk factors showed a median OS of 68 months (95% CI 68,000-68,000), and the group with neither prognosticator had a median OS of 120 months (95% CI 120,000-120,000). When included in the multivariate model, this combined risk score was the only independent predictor of OS. Conclusion The present results confirm that the combination of baseline lymph node number at MRI and PET-derived N-MTV independently allow us to identify subgroups of patients with LACC with different OS. S. Durante 1 , R. Lazzari 1 , G. Corrao 2 , S. Vigorito 3 , F. Cattani 3 , A. Aloisi 4 , V. Zanagnolo 4 , A. Maggioni 4 , N. Colombo 5,6 , B.A. Jereczek-Fossa 1,7 1 European Institute of Oncology, IRCCS, Division of Radiation Oncology, Milan, Italy; 2 European Institute of Oncology IRCCS, Division of Radiation Oncology, Milan, Italy; 3 European Institute of Oncology, IRCCS, Unit of Medical Physics, Milan, Italy; 4 European Institute of Oncology, IRCCS, Department of Gynecology, Milan, Italy; 5 European Institute of Oncology, IRCCS, Department of Oncological Gynecology, Milan, Italy; 6 University of Milan-Bicocca, School of Medicine and Surgery, Milan, Italy; 7 University of Milan, Department of Oncology and Hemato-oncology, Milan, Italy Purpose or Objective Intraoperative radiotherapy (IORT) is a modality that allows for a additional high, single radiation dose to be delivered safely while minimizing the dose to adjacent normal tissues. For this reason, IORT is well suited as an adjunct to tumor resection in patient with persistent or recurrent gynecologic malignancies undergoing pelvic exenteration (PE). The present study aimed to review our experience using IORT at the time of PE, in terms of disease free survival (DFS) and overall survival (OS). Materials and Methods We conducted a retrospective monocentric study from January 2001 to March 2019. Inclusion criteria were the following: 1) patients with a diagnosis of persistent or recurrent, previously heavy treated, gynecologic malignancies who underwent planned PE with curative intent; 2) all gynecological cancer were considered; 3) IORT administration planned for not radical surgical margin (SM), positive lymphonodes or microscopic disease extended to <1 mm of the resection SM. Results Overall 55 patients mactched inclusion criteria. Baseline characeristics are summarized in table 1. IORT was delivered because of positive lymph nodes in 12 cases, of positive SM in 19 cases and in 24 patients because microscopic disease extended to <1 mm of the resection margins. The median follow-up was 35 months (range, 3-152 months). Overall 3-year DFS was 34.7% (median 11.8 months, 95% CI 6.1-17.6) and 3-year OS was 41.8% (median 24 months, 95% CI 14.5-33.5). SM were classified as negative (36 of 55, 65.5 %) or positive (19 of 55, 34.5%). The 3-year local control rate was 64.4% in patients with negative SM compared to 45.7% in patients with positive SM (P=0.6). 23 patients relapsed (57.5%), 18 of those in the IORT field. The identified risk factors associated with high risk of recurrence in field of IORT were cervical cancer (HR 10.3, 95% CI 1.2-86.5, P=0.03) and Grade 3 histology (HR 10, 95% CI 1.1-95.2, P=0.04). We also observed a trend in the correlation between positive SM and risk of recurrence in IORT field. Table 1: Patients’ Characteristics (N=55) PO-1413 IORT at the time of pelvic exenteration in persistent or recurrent gynecologic malignancies