S683
Clinical – Lower GI
ESTRO 2026
Poster Discussion 621 Pre-Treatment PLR and NLR Predict Local Control After Escalated-Dose SBRT in Borderline and Locally Advanced Pancreatic Cancer Laura Ferrera-Alayon 1 , Antonio Alayón-Afonso 1 , Barbara Gabriela Salas-Salas 1 , Nereida Rodríguez- González 1 , Alba López-Carmona 1 , Gemma Calvet- Molinas 2 , Pedro C Lara 3,4 , Marta LLoret-Sáez-Bravo 1 1 Radiation Oncology, University Hospital Dr Negrín Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain. 2 Radiation Oncology, University Hospital Santa Creu i Sant Pau, Barcelona, Spain. 3 Radiation Oncology, Canarian Institute for Cancer Research, Las Palmas de Gran Canaria, Spain. 4 Department of Oncology, University Hospital San Roque, Las Palmas de Gran Canaria, Spain Purpose/Objective: BackgroundSystemic inflammation plays a crucial role in tumor progression and treatment response in pancreatic ductal adenocarcinoma (PDAC). The platelet-to-lymphocyte ratio (PLR) and neutrophil-to- lymphocyte ratio (NLR) have been proposed as accessible prognostic biomarkers, but their predictive value in patients undergoing high-dose stereotactic body radiotherapy (SBRT) remains unclear.Purpose / ObjectiveTo assess the prognostic value of pre- treatment PLR and NLR in patients with borderline resectable (BRPC) and locally advanced pancreatic cancer (LAPC) treated with neoadjuvant chemotherapy followed by escalated-dose SBRT. Material/Methods: Thirty-three patients with histologically confirmed BRPC or LAPC were prospectively enrolled between June 2017 and December 2022 in a multicenter academic study. All received multi-agent neoadjuvant chemotherapy (mFOLFIRINOX or gemcitabine/nab- paclitaxel) followed by escalated-dose SBRT (45–55 Gy in 5 fractions) delivered with a simultaneous integrated boost technique. Pre-SBRT PLR and NLR were calculated from routine blood counts and stratified by median values (PLR = 88.7; NLR = 2.18). The primary endpoint was freedom from local progression as first failure (FFLP-FF). Secondary endpoints included cancer-specific survival (CSS) and overall survival (OS). Survival outcomes were estimated using Kaplan–Meier curves and compared with the log-rank test. Results: After a mean follow-up of 24 months (range 6–71), the 2-year FFLP-FF rate was 80.2% for the entire cohort. Patients with high PLR ( ≥ 88.7) showed significantly reduced FFLP-FF (p = 0.038), CSS (p = 0.037), and OS (p = 0.018). High NLR ( ≥ 2.18) also correlated with worse FFLP-FF (p = 0.014). Those with both elevated PLR and NLR exhibited the poorest local control outcomes (p <
achieve complete clinical response, and 11 developed regrowth during follow-up, resulting in a 5-year local control (LC) rate of 56.7% (SE 8.5%). LC by tumor stage was T1: 78.8% (SE 9.5%), T2: 80.4% (SE 10.2%), T3: 17.0% (SE 10.8%). Salvage surgery was performed in 14 patients (87.5%), 11 patients (68.7%) remained recurrence-free. The 5-year disease-specific and overall survival rates were 65.5% (SE 12.6%) and 71.3% (SE 7.3%), respectively (Figure 1). Late-toxicity was acceptable, with 15 Grade 1 and 9 Grade 2 gastrointestinal events.
Conclusion: Curative CRT followed by a WW strategy is a feasible and effective option for selected patients with rectal cancer who are ineligible for clinical trials. The greatest potential for organ preservation is seen in patients with T1–T2 tumors. In T3 disease, local regrowth remains a concern; however, the majority of cases can be successfully salvaged surgically. Keywords: Rectal cancer, chemoradiotherapy, Watch- and-Wait
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