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Poster: Physics track: Radiation protection, secondary tumour induction and low dose PO-1429: Risk for radiation-induced cancer following proton vs.photon radiotherapy of mediastinal lymphoma L. König, P. Haering, C. Lang, B. Von Nettelbladt, F. Weykamp, P. Hoegen, M. Susko, K. Herfarth, J. Debus, J. Hörner-Rieber. [Extracted from the article]

Poster: Clinical track: Breast PO-0969: Stereotactic body radiotherapy in extracranial oligometastatic or oligoprogressive breast cancer F. Weykamp, L. König, K. Seidensaal, T. Forster, P. Hoegen, S. Akbaba, M. Susko, A. Schneeweià , J. Debus, J. Hörner-Rieber. [Extracted from the article]

An integrated heterogeneous system of HIS–RIS–PACS, modalities and image distribution must imply that all data common to all or to a subset of the environment components be consistent and compatible in their structure and their content. It is not sufficient to guarantee that all interface data formats comply with definitions and various standards. Just as important is the common semantic understanding of the data content in the various interface and database fields. One of the subproblems connected to this general requirement is that the identification criteria of all data objects must be consistent within all components. We have developed a mechanism and implemented a prototype tool to check the correctness of the set of identification criteria associated with the essential data objects within our hospital information system (HIS), radiology information system (RIS) and picture archive and communication system (PACS). Our goal was to demonstrate the feasibility and necessity of employing such encompassing tools in a HIS–RIS–PACS environment. From application of this prototype, we found discrepancies in consistency varying between 0.14% and 8% of the amount of data records in the database, depending on the type of inconsistency. This makes it mandatory to develop and employ such tools within commercially available product spectrums of RIS and PACS. [Copyright &y& Elsevier]

Poster: Clinical track: Upper GI (oesophagus, stomach, pancreas, liver) PO-1061: Stereotactic body radiotherapy for adrenal metastases of oligometastatic or oligoprogressive tumors L. König, M.F. Häfner, S. Katayama, S.A. Koerber, E. Tonndorf-Martini, D. Bernhardt, B. Von Nettelbladt, F. Weykamp, P. Hoegen, S. Klüter, M.S. Susko, J. Debus, J. Hörner-Rieber. [Extracted from the article]

The aim of this trial was to investigate the oncological benefit of a re-irradiation based on O-(2-[18F]fluoroethyl)-L-tyrosine (FET) positron emission tomography (PET) for patients with recurrent glioblastoma (rGBM) as compared to a re-irradiation based on contrast-enhanced T1-weighted magnetic resonance imaging (T1Gd-MRI). GLIAA was a prospective, multicenter, randomized clinical trial (NOA 10/ARO 2013-1, DKTK-a., NCT01252459). Patients with rGBM of 1-6 cm were randomized 1:1 at 14 centers in Germany between a FET-PET-based target volume delineation (experimental arm A) and a T1Gd-MRI-based target volume delineation (control arm B) and received high-precision stereotactic re-irradiation with 39 Gy à 3 Gy, 5x/week. Follow-up was performed by MRI and suspected progression was confirmed by FET-PET or histology, whenever possible. Primary endpoint was progression-free survival (PFS) from randomization. Secondary endpoints included overall survival (OS), locally controlled survival (LCS), recurrence patterns, and safety. Between November 26, 2013 and September 2, 2021, 200 patients were randomized between FET-PET-based (n = 100) and GdT1-MRI-based (n = 100) target volume delineation, of whom n = 98 and n = 97 patients, respectively, were treated per protocol. Median PFS was 4.0 months (95% confidence interval [CI] 3.7-5.2) in the FET-PET arm and 4.9 months (95% CI = 3.7-6.0) in the GdT1-MRT arm (one-sided stratified log-rank test P = 0.98; adjusted HR for the experimental versus the control arm 1.14 [95% CI = 0.85-1.52], P = 0.39;). Median OS was 9.4 months (95% CI = 7.8-11.1) in the FET-PET arm and 9.0 months (95% CI = 7.6-10.5) in the GdT1-MRI arm (HR 1.01 [95% CI = 0.75-1.37], P = 0.92). Median LCS was 6.3 months (95% CI = 5.1-7.2) in the FET-PET arm and 6.8 months (95% CI = 6.2-7.3) in the GdT1-MRI arm (HR 1.20 [95% CI = 0.88-1.62], P = 0.25). At 12 months, the local control rate was 22% in the FET-PET arm (95% CI = 14%-31%) and 20% in the GdT1-MRI arm (95% CI = 12%-29%). In the PET arm, 45.0% of recurrences were in field, 28.3% out of field, and 21.7% marginal. In the MRI arm, 47.4% relapsed in field, 31.6% out of field, and 14.0% marginal. Radiation necrosis was documented in 25.5% of cases in the FET-PET arm and in 21.6% in the GdT1-MRI arm. There were no adverse events related to the application of the FET tracer. The GLIAA trial could not identify an oncological benefit of the FET-PET-based rGBM-re-irradiation as compared to the GdT1-MRI-based treatment. Consequently, both imaging modalities remain valid for radiotherapy planning in this case. Both the FET-PET investigation and the re-irradiation were well-tolerated, supporting the safety of this treatment. [ABSTRACT FROM AUTHOR]

Radiotherapyof the resection cavity following brain metastasis (BM) resection improves local control. Single-session stereotactic radiosurgery (SRS) can reduce toxicity compared to whole-brain radiotherapy (WBRT). Hypofractionated stereotactic radiotherapy (HFSRT) can deliver a higher biologically effective dose, potentially improving local control over SRS. The ESTRON trial compared HFSRT of the cavity with post-operative WBRT in patients with 1-10 BM. Eligible patients with 1-10 newly diagnosed BM and following the resection of one BM regardless of histology were randomized 1:1 to receive HFSRT of the cavity and SRS of all unresected lesions or WBRT. A dose of 7 × 5 Gy was delivered to the cavity with a safety margin of 3-4 mm based on highly sensitive and standardized magnetic resonance imaging (MRI). The primary endpoint was intracranial control. Key secondary endpoints were overall survival (OS), safety, quality of life and neurocognitive function. 54 patients were randomized; HFSRT n=27, WBRT n=27. Most common histologies were non-small cell lung cancer (54%) and breast cancer (13%). Median cavity diameter was 28 mm (Q1-Q3: 22-33). 27 patients (52%) had at least one and 14 patients (26%) had >3 unresected BM. 15 patients (29%) had residual tumor at the cavity. These characteristics did not differ significantly between arms. At 12 months, intracranial control (IC) was 44% in the HFSRT and 59% in the WBRT arm. Median intracranial progression-free survival was 4.7 months (Q1-Q3: 1.7-18.0) in the HFSRT arm and 15.2 months (Q1-Q3: 5.6-12.7) in the WBRT arm (HR 1.72, 95%-CI: 0.94; 3.17, p = 0.080). In multivariable Cox-Regression, incomplete resection was predictive of inferior IC (HR 2.18, 95%-CI: 0.99; 4.79, p = 0.052). 3-year Local control (LC) at the cavity was 96% in the HFSRT arm and 89% in the WBRT arm (p=0.116) with a median follow-up of 19.7 months. Progression occurred distant from the cavity in 96% of cases (n = 26 out of 27). Leptomeningeal disease (LD) occurred in 7 patients (26%) in the HFSRT arm and 2 patients (7%) in the WBRT arm. LD occurred out of field in 6/7 cases in the HFSRT arm. 4 patients (15%) in the HFSRT arm and none in the WBRT arm developed blood brain barrier disruption at the cavity; 2 of those were symptomatic requiring treatment. Median OS was 10.3 months (Q1-Q3: 3.7-19.5) in the HFSRT arm and 18.6 months (Q1-Q3: 7.2-26.6) in the WBRT arm (HR 1.38, 95%-CI: 0.72; 2.66, p = 0.336). Following the resection of BM, HFSRT of the resection cavity provides excellent local control. Compared to WBRT, distant intracranial progression and LD remain a relevant risk and rigorous follow-up is warranted. Detailed analyses on neurocognitive function are pending. [ABSTRACT FROM AUTHOR]

Stereotactic Radiosurgery (SRS) is increasingly used as an alternative to whole-brain radiotherapy (WBRT) in the treatment of patients with multiple brain metastases (BM) with the aim of reducing toxicity and improving tumor control. The CYBER-SPACE trial evaluated SRS based on highly sensitive magnetic resonance imaging (MRI) for patients with 1-10 BM with the aim of avoiding or delaying WBRT. Eligible patients with 1-10 newly diagnosed BM regardless of histology were randomized 1:1 to receive SRS of all visible lesions based on either SPACE (sampling perfection with application optimized contrasts using different flip angle evolution) or MPRAGE (magnetization-prepared rapid gradient-echo) MRI sequence. If during follow-up new BM occurred, SRS was repeated for those BM. The primary endpoint was ineligibility for further SRS. It was defined as the simultaneous new occurrence or progression of more than 10 BM or leptomeningeal disease. Key secondary endpoints were overall survival (OS), safety, quality of life and neurocognitive function. 202 patients were randomized; SPACE n = 99, MPRAGE n = 103. Most common histologies were non-small cell lung cancer (63%), melanoma (16%) and breast cancer (10%). At data cutoff after 24 months, the probability of ineligibility for further SRS (iffS), considering death as a competing event was 21.7% (95%-CI: 16.1%; 27.9%) in the overall cohort, 23.9% (95%-CI: 15.9%; 32.9%) in the MPRAGE arm and 19.4% (95%-CI: 11.8%; 28.3%) in the SPACE arm. Median time to iffS was not reached in either arm. There was no significant difference between SPACE and MPRAGE in time to iffS (p=0.411). In multivariable Cox-Regression, 5-10 BM (vs. 2-4 BM) on initial MRI were predictive for shorter time to iffS (HR 3.13, 95%-CI: 1.53; 6.40, p = 0.002). Median OS was 13.1 months (Q1-Q3: 5.2-44) in both groups combined, 10.5 months (Q1-Q3: 5.1-30.4) in the SPACE arm and 15.2 months (Q1-Q3: 5.6-45.0) in the MPRAGE arm, with no significant difference between arms (p=0.585). In multivariable Cox-Regression, predictors for longer OS were a Karnofsky Performance Status >80% (HR 0.51, 95%-CI: 0.33; 0.77, p = 0.002), concomitant immunotherapy (HR 0.34, 95%-CI: 0.23; 0.52, p < 0.001) or targeted therapy (HR 0.51, 95%-CI: 0.34; 0.78, p = 0.002), however not the initial number of BM. Cause of death was known for 108 of 138 patients (78.3%). 14 patients (10.1%) died from BM, 94 patients (68.1%) from extracranial causes. SRS for patients with 1-10 BM avoided the need for WBRT in 79.2% of cases, when repeated upon occurrence of new lesions. Regular high-sensitivity MRI is a prerequisite for this strategy. Proactive management of multiple BM with SRS can greatly limit the impact of BM on overall prognosis. [ABSTRACT FROM AUTHOR]

Although SRT is preferred for limited brain metastases from most histologies, WBRT has remained the standard of care for patients with SCLC. It remains unclear whether the benefit of WBRT to SRT for the intracerebral tumor control outweighs the potential neurocognitive risks in SCLC patients. This pilot-trial is a single-center prospective, randomized, two-arm Phase II study. The primary endpoint is neurocognition after cerebral irradiation in SCLC patients treated with WBRT or SRT (radiosurgery (SRS) with 20 Gy or 18 Gy or hypofractionated SRT with 30 Gy in 5 Gy fractions for lesions >3 cm) defined as a drop of at least 5 points from baseline in Hopkins Verbal Learning Test–Revised (HVLT-R) total recall subscale at 3 months after baseline. Eligible patients had histologically confirmed SCLC, MRI-confirmed cerebral metastasis (not resected, maximum number of 10), Karnofsky performance score >50 and no prior irradiation to the brain. Patients were randomly assigned (1:1) to either SRT or WBRT. Secondary endpoints included survival parameters, quality of life, toxicity and neurocognitive assessments. 56 patients were randomized to either WBRT or SRT. The modified intention-to-treat (mITT) set included all randomized patients, who started study treatment with WBRT (n=25) or SRT (n=26). Prior to imputation, the primary endpoint was reached in 7.7% (n=2) of patients in the SRT group and 24.0% (n=6) of patients in the WBRT group (mITT set). After multiple imputation via predictive mean matching, the primary endpoint was analyzed using the Cochrane-Mantel-Haenszel test stratified for time of appearance (p=0.0723). For preliminary OS analysis in the mITT set, data up to 6 months were considered. Patients not having reached the endpoint were censored at 181 days. There was no significant difference in survival probability between treatment groups (p=0.36). Median time to death (at 6 months) was 124.0 (Q1 43.0- Q3 139.5) days in the SRT group and 131.0 (Q1 107.0-Q3 150.0) in the WBRT group. SCLC patients in the WBRT group were at a greater risk of a significant decline in neurocognitive function 3 months after baseline compared with the SRT group. SRT should be considered one of the standards of care for patients with brain metastases from SCLC. [ABSTRACT FROM AUTHOR]

Poster: Physics track: Intra-fraction motion management PO-1652: In silico trial of cone-beam-CT guided adaptive planning for radiotherapy of locally advanced NSCLC P. Hoegen, C. Lang, S. Akbaba, P. Häring, M. Splinter, A. Miltner, M. Bachmann, C. Stahl-Arnsberger, T. Brechter, D. Bernhardt, S. Klüter, M. Syed, F. Weykamp, L. König, J. Debus, J. Hörner-Rieber. [Extracted from the article]