ESTRO 2022 - Abstract Book

S1067

Abstract book

ESTRO 2022

1 PRINCESS MARGARET CANCER CENTER, RADIATION ONCOLOGY, TORONTO, Canada; 2 Princess Margaret Cancer Center, Radiation Oncology, Toronto, Canada; 3 TECHNA institute, University Health Network, Toronto, Canada; 4 Princess Margaret Cancer Center, Biostatistics, Toronto, Canada Purpose or Objective Tumor hypoxia is believed to be one of the contributors for treatment failure in non-small cell lung cancer (NSCLC), but has not been extensively evaluated as a prognostic/predictive factor in lung cancer. Hypoxia tracer 18 F-Fluoroazomycin Arabinoside ( 18 F-FAZA) provides a non-invasive method of hypoxia imaging. This prospective study aims to evaluate the feasibility and potential benefits of using FAZA-PET scans to assess NSCLC tumor hypoxia. Materials and Methods Patients diagnosed with stage II–III NSCLC have been recruited in this ongoing study, starting from January 2015. We report on the initial 27 patients. All patients have been imaged with 18 F-FAZA PET before initiation of curative radiotherapy, along with standard 18 F-FDG PET for staging workup. The maximum standard uptake value (SUVmax) of 18 F-FAZA PET images, hypoxic volume (HV), Tumormax/Bloodmean (T/B) ratio and hypoxic fraction (HF) were described for primary and nodal tumors. Recurrence free survival (RFS) and overall survival (OS) were calculated from radiotherapy completion date to any recurrence (local/regional/ distant) and date of death from any cause, respectively. Spearman correlation and kappa coefficient were used to explore potential correlation and agreement among several variables such as: primary and nodal tumor volume, 18 F-FAZA/hypoxia and 18 F-FDG parameters, and clinical outcomes. Results Intra-lesional hypoxia were identified in 21/27 (78%) patients for primary tumor volume, 14/27 (52%) patients for nodal tumor volume, and 22/27 (81%) patients overall. Larger primary tumor volume is correlated with higher T/B (p=0.01) and higher HF (p=0.01). Primary tumors with higher T/B ratio also had higher HF (p<0.0001). The same correlations also apply to nodal disease. Nodal FAZA SUVmax correlated with primary FAZA SUVmax (p<0.0001). After a median follow up of 21 months, RFS and OS at 2 years is 57% and 61%, respectively. Higher nodal volume is significantly associated with poorer overall and recurrence free survival, and time to distant recurrence. Conclusion Intra-lesional hypoxia in NSCLC primary and nodal tumors can be detected by 18 F-FAZA PET. Initial results are encouraging. Ongoing trial accrual and long term follow-up of our patient cohort will provide more information with regards to the imaging and clinical value of 18 F-FAZA PET. This study may eventually lead to using 18 F-FAZA PET as a guiding tool to escalate dose to the hypoxic region of lung tumors. Purpose or Objective Stereotactic body radiation therapy (SBRT) is a therapeutic option in older patients or those with comorbidities presenting central lung lesions. Most of these patients have multiple cardiovascular risk factors. This work analyzes whether the SCORE and SCORE2-OP (Older Persons) can be a useful tool to predict a worse prognosis in patients undergoing SBRT for central and ultracentral lesions. Central lesions are more likely to receive higher heart doses than peripheral lesions. SCORE and SCORE2-OP are validated scales to assess the estimated 10-year cardiovascular risk. Materials and Methods From Abril'18 to December'20, 28 patients with central lesions were radically treated with SBRT. Central lung lesions were defined according to RTOG 0813 criteria. Immobilization systems used were abdominal compressor and vacuum cushion or thorax/head-and-shoulders mask. ITV was defined by 4D RPM-Varian™.PTV was obtained by a 5mm uniform expansion of the ITV. We retrospectively reported all baseline cardiovascular risk factors and calculated their individual cardiovascular risk according to SCORE (patients with < 65y) or SCORE2-OP (patients with >65y). Kaplan-Meier survival was calculated to estimate overall survival according to SCORE / SCORE2-OP. We reported cardiac toxicity based on CTCAE v5.0. UK consensus constraints were applied. Results 10 patients with early-stage non-small cell lung cancer, 5 non-biopsed lesions and 14 central and ultra-central lung metastases were analysed. 21 were central and 4 ultra-central lesions. Mean follow-up was 16 months (3-33). Two regimens were used: 750cGy in 8 fractions or 1000-1100cGy in 5 fractions. Mean age was 70y (52-89). Mean GTV/PTV size was 26/57.6cc (0.8-100/6.1-219). Local control was 96% at 12 months. Patients were classified into 2 groups according to individual SCORE / SCORE-OP risk results: 10-year cardiovascular risk < 15% (group 1) or ≥ 15% (group 2). Estimated overall survival was 93% and 70% at 12 months in group 1 and 2 respectively (f igure 1 ). No > G3 cardiac toxicities were found. PO-1264 SCORE/SCORE2-OP cardiovascular risk and lung stereotactic body radiation therapy M. Rodriguez Pla 1 , A. Aliaga Chueca 1 , M. Soler Rodríguez 1 , R. García Gómez 1 , E. Jordá Sorolla 1 , M. Maroñas Martín 1 , D. Dualde Beltrán 1 , E. Ferrer Albiach 1 1 Hospital Clínico Universitario de Valencia, Radiation Oncology, Valencia, Spain