ESTRO 2021 Abstract Book

S1016

ESTRO 2021

191 patients with 287 HCC-lesions who received interstitial HDR brachytherapy between 01/2006 and 01/2018 in Magdeburg could be included in this analysis. 35 patients (18.3%) received two fractions, due to size or location of the liver-lesion, the other cohort could be treated with a single iBT. All patients were at Child-Pugh (CP) stage A or B and could be assigned to stages A to C according to the Barcelona-Clinic-Liver-Cancer (BCLC-) classification. The median dose, taking into account the institutional dose limitation for the liver and surrounding organs (OAR), was about 15 Gy. Retrospectively, the ALBI score and the IBI index were calculated at the time before the iBT, immediately thereafter as well as 3 and 6 months post iBT. In the case of an intermittent change to other therapy modalities, the serum parameters were not further recorded. Subsequently, an evaluation of the influence of the indices on the OS and the PFS was carried out. Results For the total cohort, median OS following iBT was 23 months (95% confidence interval [CI]; 19-28), median PFS 8 months (95% CI; 7-8). The mortality risk increased with the degree of ALBI score before therapy: in Grade 2 patients by a factor of 1.957 (p < 0.001), in Grade 3 patients by a factor of 4.176 (p = 0.001), compared with the cohort with ALBI score 1. Similarily, the risk of mortality increases by a factor of 1.731 (p = 0.005; IBI 1 vs. 0) or 4,768 (p < 0.001; IBI 2 vs. 0). Persistent or rising ALBI and IBI scores after therapy and in the follow up until 6 months significantly increase the mortality risk significantly to at least 5% (exception ALBI score 2 vs. 1 immediately after therapy). PFS also correlates with the ALBI score and IBI index. An ALBI score of 3 vs. 1 resulted in the risk to experience a progression by a factor of 2,507 (p = 0.014; FU < 3 months); 2,116 (p = 0.013; FU after 3 months) and 2,517 (p = 0.003; FU after 6 months). A rising of the IBI index from 0 to 2 results in a risk increase of 1.768 (p = 0.023) and an increase in the Child-Pugh score from A to B results in a growing mortality risk by a factor of 2.418 (p = 0.001) and to experience a progression of 2.119 (p = 0.021). Conclusion In this retrospective study, both ALBI score as well as IBI index had a significant impact on OS and PFS. This influence should be further investigated in prospective studies, in order to identify patients at risk and thus better adapt the indicated therapy modality. PO-1230 18F-FDG PET-CT as prognosis factor after neoadjuvant chemoradiotherapy in esophageal cancer B. Moura Fernandes 1 , D. Correia 1 , I. Félix Pinto 1 , S. Couto Gonçalves 1 , I. Nobre Góis 1 , J. Casalta Lopes 1 , A. Barros 2 , M. Borrego 1 1 Coimbra Hospital and University Center, Radiation therapy, Coimbra, Portugal; 2 Coimbra Hospital and University Center, Oncology, Coimbra, Portugal Purpose or Objective Pathologic complete response after neoadjuvant chemoradiotherapy in esophageal cancer is associated with better outcome. PET-CT with 18 F-FDG (PET) has a major role in the stagging and response evaluation in these patients, with potential prognostic value. The main objective with this work is to evaluate the correlation between clinical response in PET (SUV max ) and pathologic complete response (pCR) after neoadjuvant chemoradiotherapy, while assessing their prognostic impact. Materials and Methods In this work were included patients with non-metastatic esophageal cancer, submitted to neoadjuvant chemoradiotherapy between 01/2014 and 05/2020 with pre-treatment PET scan and post neoadjuvant chemoradiotherapy PET scan. Treatment toxicity, clinical response in PET and pathologic response were assessed. Survival analysis by Kaplan-Meier method. Receiver operating characteristic (ROC) curves were established to evaluate discriminative power of post-treatment PET SUV max and relative reduction of SUV max (relSUVred) between pre and post treatment PET in the prediction of locoregional recurrence. Cutoff value determined by Youden index. α=0.05. Results 41 patients, 85.4% male, median age 64 years (37-81). Symptoms at time of diagnosis: weight loss in 59.0%, dysphagia in 87.8%, need for esophageal dilatation before the start of the treatment 4.9%. 59% were active smokers and 73.7% active alcohol drinkers. Location of 41.5% of the tumors in the mid esophagus, 31.7% at the esophagogastric junction, 14.7% at the lower esophagus and 12.2% at the upper esophagus. Staged as cT3 87.8% and cN+ 70.7%. 73.2% epidermoid carcinoma. Surgery was done in 85.4%, 34.3% ypT0, 77.1% ypN0, 85.7% LVI0, pCR 31.4%, 100% R0 resection. Median SUV max in the pre-treatment PET 12.2 [3.0;28.7]. Median SUV max reduction between pre and post- treatment PET 9.92 (p<.001), Median SUV max in post-treatment PET 3.1 (0-9.6), relSUVred 0.7642 (0.27-1.0), complete clinical response in 8 patients. pCR observed in 11 patients, 2 of them with complete clinical response. Median follow-up 18 months. At 12 months overall survival (OS) 60.6%, disease specific survival (DSS) 74.3%, disease free survival (DFS) 76.6%, locoregional failure free survival (LRFFS) 89.4%. ROC curve for SUV max in the post-treatment PET showed an area under the curve (AUC) .794 (p=.015), with a cutoff value of 4 (sensitivity (Se) 85.7% and specificity (Sp) 67.6%), with an impact in OS (p=.025), DFS (p=.003) and LRFFS (p=.003). ROC curve for relSUVred had an AUC .729 (p=.059), with a cutoff value of .7492 (Se=64.7%, Sp=85.7%), with statistical significative impact in SLDLR (p=.006). Conclusion A SUV max <4 in the post-treatment PET is associated with a better OS, LRFFS and DFS. A relative SUV reduction >.7492 was associated with a better LRFFS. Quantitative evaluation of PET may constitute a prognosis factor, although it is necessary a larger sample. Also, other PET parameters might be useful in prognostic assessment.