ESTRO 2020 Abstract book

S717 ESTRO 2020

There were no late severe complications. In our group of 32 patients, one local recurrence was noted. None of the patients suffered from distant metastasis. The five-year DFS was 93,75% Conclusion APBI with Interstitial Multicatheter High-Dose-Rate Brachytherapy is a safe and effective method. It can be taken into consideration in the management of elderly female breast cancer patients as an adjuvant treatment after previous surgery. PO-1271 Lung stereotactic ablative radiotherapy in elderly patients: safety and efficacy C. Cavallin 1 , S. Badellino 1 , M. Cerrato 1 , D. Caivano 1 , I. Chiovatero 1 , A. Vella 1 , J. Di Muzio 1 , C. Mantovani 1 , M. Levis 1 , U. Ricardi 1 1 Ospedale Molinette University of Turin, Dept. of Radiation Oncology, Torino, Italy Purpose or Objective Given the rise of population aging and the implementation of screening programs, the incidence of lung growing lesions between elderly patients is increasing. Moreover these patients may be at significant risk of morbidity and mortality associated with invasive diagnostic and therapeutic option. In this setting, Stereotactic Ablative Radiation Therapy (SABR) can play a unique role in patients suitable for curative treatment. Aim of this study was to report the outcomes of a cohort of very elderly patients (aged 80 or older) treated by SABR for stage I NSCLC in terms of Local Control (LC), Progression-Free Survival (PFS), Overall Survival (OS), Metastasis-Free Survival (MFS) and toxicity. Material and Methods We retrospectively analized a cohort of 184 consecutive elderly patients who underwent SABR at our Institution from September 2004 to December 2018. Of these, 69 had a histologically proven NSCLC, whereas 115 were treated on the basis of a radiologic evidence, in accordance with a “clinical proof of malignancy”. One-hundred and fifty patients were male (81,5%) and 34 female (18.5%). One hundred thirty-five patients had stage IA disease (75%), 39 patients stage IB disease (21%) and 8 patients stage IIA (4%). Total doses administered ranged from 26 to 60 Gy (1- 8 fractions). At baseline evaluation, ECOG PS was 0 in 128 patients (70%), while ECOG PS was > 1 in 56 patients (30%). Median age of patients was 82 (SD: ± 2), the median volume of PTV was 43 cc (SD: ± 29), the median BED was 112,5 Gy (SD: ± 16). Results

With a median follow-up time of 25 months, we reported an overall response rate (complete response, partial response, stable disease) of 94%. The LC rates were 94% and 86%, respectively, at 2 and 5 years. The median PFS time was not reached, while PFS at 2 and 5 years was 73% and 57%, respectively. MFS at 2 years was 80%, with an actuarial rate of 67% at 5 years. At last follow-up there were 48% of patients alive, with OS rates of 68% and 36% at 2 and 5 years, respectively. At the univariate analysis 2 parameters were related to a poorer outcome in terms of OS and MFS: PTV >45 cc (p 0.036) and BED <110 Gy (p 0.007). No clinical or dosimetric factor had an impact on LC. SABR was well tollerate by all patients, with only one case of G4 acute and late toxicity (RTOG scale). Conclusion SABR is an effective and tolerable treatment option for older patients who are not suitable for surgery, with local control rates approximating 94%. In our opinion, this treatment option should be considered for elderly patients with a lung lesion suspicious for early stage NSCLC. We recommend careful evaluation in a multidisciplinary approach in order to provide individualized care to maximize disease control while minimizing treatment- related morbidity and mortality. PO-1272 Immunoradiotherapy induces a rechallenge of the immune response in elderly patients. M.A. Zajac 1 , R. Chicas-Sett 1 , I. Morales-Orue 2 , J. Castilla Martinez 1 , J. Zafra 1 , J. Blanco 1 , A. Kannemann 1 , M. Lloret Saez-Bravo 1 , P. Lara 3 1 The Doctor Negrin University Hospital of Gran Canaria, Radiation Oncology Department, Las Palmas de Gran Canaria, Spain ; 2 Hospital Punta Europa, Radiation Oncology Department, Ageciras, Spain ; 3 University Hospital San Roque/University Fernando Pessoa, Oncology Department, Las Palmas de Gran Canaria, Spain

Purpose or Objective