ESTRO 2021 Abstract Book

S987

ESTRO 2021

oligometastasis). In 20 primary lung cancer patients (12 Adenocarcinoma, 6 SCC, 1 neuroendocrine,1 no biopsy) 14 male patients, mean age 70 yrs (38-90 yrs), 13 had co-morbidities, peripheral lesions 15, central lesions 5, right lung 15, left lung 5, 9 (45%) had stage I and 5 (25%) stage II. Six (30%) patients with primary lung cancer and metastasis underwent RT for both metastatic and primary site. Stage IA1, IA2, IA3, IB, IIA, IIB were 1 (5%), 3 (15%), 3 (15%), 2 (10%), 2 (10%), 3 (15%) respectively. Three (15%) were treated with 22- 26Gy/1fr, 7 (35%) with 42-45Gy/3fr, 8 (40%) with 40-50Gy/5fr, 1 (5%) each with 36Gy/4fr and 48Gy/8fr. PTV mean volume 38.1 cc (8.3-88.3cc). Mean OS & PFS 14 (2-43 mo) & 8 mo (3-37 mo) respectively. At last follow up (F/U), 15 patients were alive, 3 were dead and 2 lost to F/U. In stage I and stage II disease local failure rate was 2/9 (22%) and 1/5 (20%). In primary lung with metastatic disease treated with local RT, 3/6 (50%) had local failure. Nine patients had disease progression (6 local, 3 distant). In 22 patients with 23 lung oligometastasis, 3 had synchronous and 19 had metachronous lung metastasis. Primary site colo-rectal in 9, thyroid in 3, kidney 4, head neck in 2, liver in 1, endometrium in 1, pancreas in 1, sarcoma 1. Mean age 60 yrs (36-83 yrs), 12 male patients, 7 had comorbidities. Five patients had DFI ≤ 1yr, 5 patients 1-2 yr, and 9 patients more than 2 yr. Mean PTV was 21cc (range: 2.8 – 78 cc). 18–24 Gy/1fr, 45-54Gy/3fr, 35-50Gy/1fr & 48Gy/8fr in 6, 8, 5 and 1 patient respectively. 17 patients were evaluable for ‘response to CK’ evaluation [local response 88% (15/17) with CR 76% (13/17) & PR 12% (2/17)]. 2 (12%) papillary carcinoma thyroid patients had progressive disease. At mean F/U of 11 mo, 7 (32%) were alive with controlled disease, 8 (36%) were alive with disease progression. 2 (9%) had local and distant failure and 10 (45%) had systemic progression. Mean OS & PFS 11 mo (2-26mo) and 8.5 mo (2-26mo). Median OS for synchronous oligometastasis 22 mo. At post-CK 3 mo, 1 patient required intercostal drainage and pleurodesis. Radiological complete response after CK in metastasis and primary lung cancer was 15/22 (68%) and 9/20 (45%) respectively. PTV volume (<10cc; p=0.011) and BED (>110 Gy; p=0.009) were significant factors influencing complete response to treatment. Histology (adenocarcinoma Vs SCC; p=0.416) was not significant. Conclusion SBRT with CK is safe and effective in both primary lung tumours and in lung oligo-metastasis. Higher BED in smaller volume metastasis had higher complete response. PO-1191 Immunotherapy and radiation (iRT) in a 'Real-life' setting. Analysis on safety and effectiveness A. Angrisani 1 , C. Greco 2 , E. Ippolito 2 , B. Santo 2 , S. Gentile 2 , P. Falco 2 , M. Miele 2 , M. Fiore 2 , S. Ramella 2 1 University "L. Vanvitelli", Precision Medicine - Radiation Oncology, NAPOLI, Italy; 2 Campus Bio-Medico University of Rome, Departmental Faculty of Medicine and Surgery, Radiation Oncology, Rome, Italy Purpose or Objective Combined Thoracic radiation therapy and immunotherapy (iRT) is an increasingly used strategy for NSCLC. However, there are concerns about its safety. The primary aim of our study was to evaluate the safety of this combination in a mono-institutional cohort of NSCLC patients. Secondarily we tried to observe if any abscopal We retrospectively evaluated IV stage NSCLC patients with confirmed histological diagnosis, undergoing radiation treatment and immunotherapy from 1st March 2015 to 28th February 2020 at our institution. Common Terminology Criteria for Adverse Events (CTCAE) version 5.0 was used to define acute and late toxicities. Follow-up time was calculated from the end of radiotherapy (RT). Results Fifty-one patients were evaluated. The majority of patients (74.5%, 38/51) underwent concurrent RT within immunotherapy, 21% (11/51) received at least once RT within 0 -3 months from last immunotherapy administration, 4% (2/51) underwent RT 0- 3 months before starting immunotherapy. EBRT was delivered in different settings: SBRT or long course RT to oligometastatic or oligoprogressive sites of disease (total 25 patients, 49.1%), VMAT (n=13) or 3DCRT (n=13) treatment for palliative intent in 26 patients (50.9%). The RT Planning Target Volume was localized in the thorax in 12 patients (23.5%). Mean follow-up was 10.1 Months (Range 1-24 M). 34/38 patients (89.4%) from the concomitant iRT group showed no/minimum adverse effects; 4/38 (10.6%) patients, all with thoracic PTVs, developed lung acute toxicity > G3; two of them died for G5 pneumonia after 21.6 Gy of radiotherapy and 6 months after the end of RT respectively. One patient discontinued treatment for bilateral G3 pneumonia requiring hospitalization. Treatment details of patients experiencing grade > 3 lung toxicity are summarized in table 1. In a single patient treated with SBRT to a paraortic mediastinal node concurrently with IT a reduction in FDG uptake was detected also in a supraclavicular node not irradiated at the PET-CT scan performed after SBRT during the first re-evaluation. effect of iRT occurred. Materials and Methods