ESTRO 2020 Abstract Book

S419 ESTRO 2020

Abstract text Radiotherapy is a safe and effective treatment for prostate cancer, with huge changes in our technological capabilities over the last decade. SBRT has emerged from the convergence of radiobiological research, suggesting a low alpha/beta ratio, and technological innovation, which has made conformity and dose gradients previously thought to be impossible into a reality. Birthed out of these innovations, stereotactic body radiotherapy (SBRT) for prostate cancer, treating to high daily doses in 5 or less treatments, is gathering an evidence base. For many years this data was solely from Phase II or cohort studies, but now Phase III data is emerging. This talk will review data on SBRT now dating back over a decade, including very large datasets which have been recently published. What can we learn about the safety and efficacy of SBRT from this data and do the current guidelines around the globe reflect this data? Which patients may benefit more than others from SBRT and which patient groups have not yet been adequately studied? In the last few years, Phase III evidence in support of SBRT has been presented showing equivalence of ultrahypofractionated regimens in terms of 5 year biochemical outcomes (HYPO-RT-PC) and equivalence of short term toxicity for 5 fraction SBRT (PACE B). This talk will discuss whether SBRT should be standard of care for any patient in 2020. Finally, data still continues to accrue regarding the benefits and risks of SBRT. Several large trials will publish in the next few years, which may change the landscape for many men with prostate cancer. But where do we go next? Trials are ongoing with simultaneous integrated boost techniques, as well as treating higher risk men and treating the prostate and pelvis with SBRT. Predicting where the standard of care will be in 2030 is going to be challenging. SP-0757 Treatment planning and dose constraints for Prostate Sbrt P. Mancosu 1 1 Humanitas Research Hospital, Medical Physics Unit- Radiotherapy And Oncology Dept., Rozzano Milan, Italy Abstract text Stereotactic Body Radiation Therapy (SBRT) on prostate could be delivered using different machines (dedicated or not dedicated to SBRT). There is a need to harmonize the planning procedure in order to compare different findings. This presentation will focus the pro/cons of homogeneous and not homogeneous approaches in optimizing prostate SBRT. Constraints for prostate SBRT will be presented starting from the latest recent trials (in particular thePACE-B trial).

lung cancer, inducing durable responses in a subset of patients. As of yet, our understanding about the differences in responses is sparse. High PDL1 expression levels and mutational burden seems to increase likelihood of responses, but also patients with low PDL1 expression and low tumour mutational burden can experience durable responses. The immune microenvironment is now studied elucidating factors influencing the responses to immune checkpoint inhibition. Aiming at increasing the proportion of lung cancer patients benefitting from checkpoint inhibition, efforts are being made to combine checkpoint inhibitors with other therapeutics. Stereotactic radiotherapy is one such appealing option for combination, with the idea being to induce immunogenic cell death, introducing tumour antigens into circulation and inducing an inflammatory signature. In a series of lung cancer patients, we have analysed tumour tissue by RNA expression analyses, focusing on the immune microenvironment. Gene expression was assessed in 399 surgically derived non-small cell lung cancer samples and 47 samples from normal lung, using Agilent microarray and RNA sequencing. In addition, we have investigated how the cytokine levels in serum samples vary during radiotherapy in patients with non-small cell lung cancer. Concentration levels of selected cytokines and MMPs in serum samples were evaluated by multiplex bioassays (BioRad). Lastly, we have investigated patients treated with a combination of stereotactic radiotherapy and an immune check-point inhibitor. In the expression analyses, tumors with an active immune microenvironement were found in both adenocarcinomas (AD) and squamous cell carcinomas(SCC). The immunoscore was calculated for the histological subgroups analysed, and correlated to survival. The serum levels of some cytokines and MMPs differed significantly during the course of radiotherapy. In a clinical series of patients treated with a combination of a check point inhibitor and stereotactic radiotherapy, analyses of the tumour microenvironment is underway. The immunological microenvironment is important for responses to immunotherapy. In patients with non-small cell lung cancer, radiotherapy induces systemic changes in the inflammatory / immunological environment, which may influence response to other treatment. SP-0759 Immunotherapy approaches to advanced lung cancer R. Pirker Vienna, Austria

Abstract not available

SP-0760 Immunotherapy and (chemo)radiotherapy in Stage III NSCLC Y. Lievens Ghent University Hospital, Ghent, Belgium

Joint Symposium: ESTRO-IASLC: Combined radiotherapy and immunotherapy in NSCLC

Abstract not receieved

SP-0758 The immune microenvironment in lung cancer - impact on effect of combined radiotherapy and immunotherapy? Å. Helland 1 1 Institute of Cancer Research, The Cancer Clinic, Oslo, Norway Abstract text Lung cancer is a common disease, with a poor prognosis. During the past decade, immune checkpoint inhibitors have been introduced in the treatment of non-small cell

SP-0761 Combining immunotherapy and thoracic radiotherapy in SCLC S. Senan 1 1 Amsterdam University Medical Center, Radiation oncology, Amsterdam, The Netherlands Abstract text Extensive SCLC The prognosis of patients presenting with an extensive SCLC remains poor despite standard chemotherapy and the use of prophylactic cranial