ESTRO 2022 - Abstract Book

S538

Abstract book

ESTRO 2022

Figure 1: Venn diagram showing the distribution of local and/or regional lymph node and/or distant recurrences since treatment, in the cohort of patients treated with focal salvage HDR brachytherapy. Each number represents the amount of patients in the corresponding category. Conclusion After focal salvage HDR brachytherapy with a dose of 1x19 Gy for local prostate cancer recurrence, subsequent recurrences are mostly local and in-field. Contrarily, local recurrences after primary HDR brachytherapy are predominantly out-of- field.

OC-0613 Pre-treatment Neutrophil to Lymphocyte Ratio predicts Overall Survival in Prostate Brachytherapy

S. Garcia 1 , P. Fernandes 1 , L. Trigo 1

1 IPO Porto, Brachytherapy, Porto, Portugal

Purpose or Objective As the interest in studying the immune system and its relation with the development and progression of several types of cancer rose, the concept of neutrophil to lymphocyte ratio (NLR) emerged as a significant prognostic factor in various tumours. Its role in prostate cancer has been studied mainly in the metastatic setting, where NLR > 2 was found to be associated with worse overall survival (OS). This study aims to evaluate the relation between the NLR and disease free survival (DFS), OS and disease specific survival (DSS) on low-intermediate risk prostate cancer patients treated with iodine- 125 brachytherapy (I-125 BT) mono therapy. Materials and Methods This retrospective study included low-intermediate risk prostate cancer patients, treated with I-125 BT mono therapy between January 2013 and October 2016, in a single tertiary centre. Biochemical recurrence was defined according with Phoenix consensus criteria and a NLR of >2 was assumed for high NLR. Statistical analysis was performed with SPSSv.27, and a p < 0.05 was considered statistical significant. The influence of NRL on DFS, OS and DSS was analysed using log rank test for univariable analysis and Cox regression for multivariable analysis. Results In total, 250 patients were included; with a median age of 64 years. Median follow-up period was 79 months (39 – 105 months). Biochemical control was observed in 232 patients. Of the 132 patients with high NLR, 9 experienced biochemical recurrence (p=0.76). OS at 5 years was 97.7% for NRL high (p=0.009). The impact of high NRL on OS was confirmed in Cox regression (p=0.045). DFS and DSS at 5 years were 93.4% and 100% for high NLR, respectively (p=0.76; p=0.29 respectively). There were also no significant differences in DFS or DSS in Cox regression (p=0.08; p=0.97 respectively). Conclusion In this study, high NLR of >2 was a strong predictor for worse OS in patients with low- and intermediate-risk prostate cancer treated with I-125 BT mono therapy, in log rank and cox regression. The NLR has the advantage of being widely assessable and inexpensive, but the cut-off values vary significantly among studies. To the authors best knowledge, this is the first study of is type conducted exclusively in localized prostate cancer treated with I-125 BT mono therapy. No association was found between NRL and DFS or DSS, but several studies came to the same results. Further investigation is needed to understand how systemic inflammation may modulate cancer natural history.

OC-0614 HDR-BT for primary tumors and relapses after surgery in patients with BCC of the H&N region.

A. Chyrek 1 , W. Burchardt 1 , G. Biel ę da 2 , M. Adamska 3 , A. Chiche ł 1

1 Greater Poland Cancer Centre, Brachytherapy Department, Pozna ń , Poland; 2 Greater Poland Cancer Centre, Medical Physics Department, Pozna ń , Poland; 3 Greater Poland Cancer Centre, 2nd Radiotherapy Department, Pozna ń , Poland