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Abstract Background and introduction Increasing evidence suggests that a subgroup of patients with oligometastatic cancer might achieve a prolonged disease-free survival through local therapy for all active cancer lesions. Our aims are to investigate the impact of brain metastases on the classification, treatment, and outcome in these patients. Materials and methods We analyzed a total of 7,000 oncological positron emission tomography scans to identify patients with extracranial oligometastatic disease (defined as ≤ 5 intra- or extra-cranial metastases). Concurrent magnetic resonance imaging brain was assessed to quantify intracranial tumor burden. We investigated the impact of brain metastases on oligometastatic disease state, therapeutic approaches, and outcome. Predictors for transitioning from oligo- to polymetastatic states were evaluated using regression analysis. Results A total of 106 patients with extracranial oligometastases and simultaneous brain metastases were identified, primarily originating from skin or lung/pleura cancers (90%, n = 96). Brain metastases caused a transition from an extracranial oligometastatic to a whole-body polymetastatic state in 45% (n = 48) of patients. While oligometastatic patients received systemic therapy (55% vs. 35%) more frequently and radiotherapy for brain metastases was more often prescribed to polymetastatic patients (44% vs. 26%), the therapeutic approach did not differ systematically between both sub-groups. The oligometastatic sub-group had a median overall survival of 28 months compared to 10 months in the polymetastatic sub-group (p

With the emergence of high-precision radiotherapy technologies such as stereotactic ablative radiotherapy (SABR), MR guided brachytherapy, image guided intensity modulated photon and proton radiotherapy and most recently daily adaptive radiotherapy, reirradiation is increasingly recognized as a viable treatment option for many patients. This includes those with recurrent, metastatic or new malignancies post initial radiotherapy. The primary challenge in reirradiation lies in balancing tumor control against the risk of severe toxicity from cumulative radiation doses to previously irradiated normal tissue.Although technology for precise delivery has advanced at a fast pace, clinical practice of reirradiation still mostly relies on individual expertise, as prospective evidence is scarce, the level of reporting in clinical studies is not standardized and of low quality − especially with respect to cumulative doses received by organs at risk.A recent ESTRO/EORTC initiative proposed a standardized definition of reirradiation and formulated general requirements for minimal reporting in clinical studies [1].As a consequence we found it timely to convene for an international and interdisciplinary meeting with experts in the field to summarize the current evidence, identify knowledge gaps and explore which best practices can be derived for safe reirradiation. The meeting was held on 15.06.2023 in Zurich and was endorsed by the scientific societies SASRO, DEGRO and ESTRO. Here, we report on available evidence and research priorities in the field of reirradiation, as discussed during the meeting.

Aims: Multidisciplinary tumor boards (MDTs) are an integral part of ensuring high-quality, evidence-based and personalized cancer care. In this study, we aimed to evaluate the adherence to and implementation of MDT recommendations in patients with oligometastatic disease (OMD). Methods: We screened all oncologic positron emission tomography (PET) scans conducted at a single comprehensive cancer center in 2020. Patients were included if they had evidence of imaging-based OMD from a solid organ malignancy on the index scans, had their OMD case discussed at an MDT, and were treated and followed up at the same center. A switch away from the MDT-recommended treatment modalities was classified as a major deviation; non-MDT-mandated adjustments to a recommended treatment modality were coded as minor deviation. Clinical data was obtained via chart review; statistical calculations were computed using the R software. Results: After review of PET and/or concurrent brain scans, 787 cases of OMD were identified. Thereof, 347 (44.1 %) cases were discussed at MDT, of which 331 (42.1 %) were therapeutically managed and subsequently followed. The three most commonly recommended therapies were systemic therapy (35.6 %), multimodality treatment including definitive local therapy (17.8 %), and radiotherapy (13.9 %). A major deviation was recorded in 16.3 % of cases (most commonly: none of the MDT-recommended treatment modalities were performed: 19 (35.2 %); not all MDT-planned treatment modalities were performed: 12 (22.2 %); and additional treatment modality was performed: 11 (20.3 %). A minor deviation was found in 1.5 % of cases. On multivariable regression, number of distant metastases (n > 1) was associated with a major deviation (OR: 1.85; 95 % CI, 1.0–3.52). Major deviations were associated with a significantly worse OS (p = 0.0034). Conclusions: Adherence to and implementation of MDT recommendations in OMD patients was generally high (83.7%). Major deviations might be further reduced by more careful and elaborate discussions of OMD patient characteristics s and patient preferences.

Background and purpose: Stereotactic body radiotherapy (SBRT) of ultra-central lung tumors (UCLT) is associated with an increased risk of severe toxicity. The aim of this study was to perform a detailed dosimetric analysis of the proximal bronchial tree (PBT) anatomical sub-segments to evaluate the safety of risk-adapted SBRT and to evaluate potential differences in radiation tolerance between PBT sub-segments. Material and methods: Fifty-seven patients treated with SBRT for UCLT between 2014 and 2021 were included. UCLT were defined as tumor abutting or overlapping with the trachea, PBT, or esophagus. This study analyzed overall survival, local control, progression-free survival, and grade ≥3 toxicity events. Bayesian inference was used to build a dose-response model with upper limits for toxicity. Results: Twenty-seven (47.4%) of the irradiated lesions were primary or locoregionally recurrent NSCLC and 30 (52.6%) oligometastases. All patients were treated with risk-adapted SBRT of median 45.0 Gy (range: 30.0-60.0 Gy) in 8 or 10 fractions. Grade ≥3 radiation pneumonitis was observed in two patients (3.5%), while no bronchial stenosis, hemorrhage or fistula were observed. The dose-response model predicted a grade ≥3 toxicity (stenosis, hemorrhage or fistula) limited to 4.9% (0 - 11.4%) when delivering EQD2_3 = 100 Gy to any location of the PBT (D0.2cc). Detailed dosimetric analysis of PBT substructures showed no variation in the dose-response model between the anatomical PBT sub-segments. Conclusion: Risk-adapted SBRT regimens delivered in 8 or 10 fractions for ultra-central lung tumors resulted in high rates of local tumor control with low toxicity rates, without differences in radiation tolerance between the anatomical PBT sub-segments.

Introduction and background: Metastatic disease has been proposed as a continuum, with no clear cut-off between oligometastatic and polymetastatic disease. This study aims to quantify tumor burden and patterns of spread in unselected metastatic cancer patients referred for PET-based staging, response assessment of restaging. Materials and methods: All oncological fluorodeoxyglucose (FDG-) and prostate-specific membrane antigen (PSMA-) positron emission tomography (PET) scans conducted at a single academic center in 2020 were analyzed. Imaging reports of all patients with metastatic disease were reviewed and assessed. Results: For this study, 7,000 PET scans were screened. One third of PET scans (n = 1,754; 33 %) from 1,155 unique patients showed presence of metastatic disease from solid malignancies, of which 601 (52 %) and 554 (48 %) were classified as oligometastatic (maximum 5 metastases) and polymetastatic (>5 metastases), respectively. Lung and pleural cancer, skin cancer, and breast cancer were the most common primary tumor histologies with 132 (23.8 %), 88 (15.9 %), and 72 (13.0 %) cases, respectively. Analysis of the number of distant metastases showed a strong bimodal distribution of the metastatic burden with 26 % of patients having one solitary metastasis and 43 % of patients harboring >10 metastases. Yet, despite 43 % of polymetastatic patients having >10 distant metastases, their pattern of distribution was restricted to one or two organs in about two thirds of patients, and there was no association between the number of distant metastases and the number of involved organs. Conclusion: The majority of metastatic cancer patients are characterized by either a solitary metastasis or a high tumor burden with >10 metastases, the latter was often associated with affecting a limited number of organs. These findings support both the spectrum theory of metastasis and the seed and soil hypothesis and can support in designing the next generation of clinical trials in the field of oligometastatic disease.

Background: Oligoprogression is defined as cancer progression of a limited number of metastases under active systemic therapy. The role of metastasis-directed therapy, using stereotactic body radiotherapy (SBRT), is controversial as is the continuation versus switch of systemic therapy. We report outcomes of oligoprogressive patients after SBRT, and compare those patients that continued or switched their current line of systemic therapy. Material/Methods.: We included patients who developed up to 5 progressive extracranial metastases under systemic therapy for any solid organ malignancy and were treated with SBRT to all lesions at our institution between 01/2014 and 12/2019. Overall survival (OS) and progression-free survival (PFS) were analyzed using the Kaplan-Meier method, and the interval to the next systemic therapy line determined using cumulative incidence functions. Multivariable Cox regression models were used to analyze the influence of baseline and post-progression variables on OS, PFS and survival with the next systemic therapy after SBRT. Results: Among 135 patients with oligoprogressive disease of which the most common primary tumor was lung cancer (n = 46, 34.1 %), 96 continued their current line of systemic therapy after oligoprogression. Among 39 who switched systemic therapy, 28 (71.8 %) paused or discontinued, while 11 (28.2 %) immediately started another systemic treatment. After a median follow-up of 27.2 months, patients that switched and those who continued systemic therapy after oligoprogression had comparable median OS (32.1 vs. 38.2 months, p = 0.47) and PFS (4.3 vs. 3.4 months, p = 0.6). The intervals to the next systemic therapy line were comparable between both cohorts (p = 0.6). An ECOG performance status of 2 and immediately starting a new systemic therapy after oligoprogression were associated with a poorer survival without next systemic therapy, while the de-novo OMD state was associated with better survival without next systemic therapy compared to the induced state. Conclusion: Oncological outcomes of patients that continued or switched systemic therapy after SBRT for oligoprogression were comparable, potentially indicating that further lines of treatment may be safely delayed in selected cases.

Background and introduction: Growing evidence supports a combined modality treatment strategy for patients with oligometastatic disease. However, lack of phase III trial data and uncertainties around patient selection highlight the importance of multidisciplinary tumor boards (MDT) in therapeutic decision-making. This study aimed to analyze the recognition of and treatment recommendations for oligometastatic patients by MDTs at a large comprehensive cancer center in order to better understand current treatment patterns of oligometastasis. Materials and methods: For this retrospective single-center cross-sectional study, oligometastatic patients were identified by screening oncological PET and concurrent brain MRI scans conducted at our center in 2020. MDT discussions and recommendations within four weeks of the imaging diagnosis of oligometastasis were analyzed. Logistic regression analysis was used to identify predictors for the addition of local therapy to standard-of-care. Results: A total of 787 oligometastatic cases were identified. Lung cancer and mesothelioma, skin cancer, and prostate cancer were the most common histologies with 231 (29 %), 160 (20 %), and 84 (11 %) cases, respectively. Almost half of the cases (46 %) had one distant metastasis on imaging only. More than half (56 %) of all oligometastatic cases were discussed at an MDT. In 47 % of cases, for which a therapeutic recommendation was reached in an MDT, local therapy was part of the therapeutic strategy. On logistic regression analysis, oligometastatic skin cancer was significantly associated with a recommendation for local therapy (p

Background and purpose: Due to advances in oncology, a growing proportion of patients is treated with repetitive courses of radiotherapy. The aim of this study is to analyze whether radiotherapy maintains its safety and efficacy profile in patients treated with multiple repeat courses of irradiation. Material and methods: All patients treated between 2011 and 2019 at our institution were screened for a minimum of five repeat irradiation courses, to analyze treatment characteristics, survival, safety and efficacy. The type of re-irradiation was classified according to ESTRO-EORTC consensus guidelines. Results: A total of n = 112 patients receiving n = 660 radiotherapy courses were included in this retrospective cohort study. The most frequent primary tumors were lung cancer in 41.9 % (n = 47) and malignant melanoma in 8.9 % (n = 10). The most frequent re-irradiation types were repeat irradiation and Type 2 re-irradiation in 309 (46.8 %) and 113 (17.1 %) cases, respectively. Median survival after the first course of radiotherapy was 3.6 (0.3–13.4) years. Response to radiotherapy was observed in 548 (83.0 %) cases and CTCAE toxicity grade ≥ 3 was observed in 21 (3.2 %) cases. An increasing number of RT courses (HR: 1.30, p=

Background: Patients who develop oligorecurrent disease may be treated with metastasis-directed stereotactic body radiotherapy (SBRT) to defer the start of systemic therapy and delay its potential side effects. We report oncological outcomes and patterns of failure in patients with oligorecurrent disease treated with SBRT and determine which factors impact the interval to initiation of systemic therapy. Material/Methods: This retrospective study included patients with oligorecurrent disease (≤5 lesions) from any solid organ malignancy, treated with SBRT to all metastases and no systemic therapy for a minimum one month after SBRT between 01/2014 and 12/2019. The Kaplan-Meier method was used to analyze overall survival (OS) and progression-free survival (PFS), and the cumulative incidence of initiation of systemic therapy was analyzed assuming death without systemic therapy as a competing risk. Univariable and multivariable analyses are used to assess predictors of the systemic therapy-free interval. Results: Among 545 patients treated with SBRT for oligometastatic disease, 142 patients were treated with SBRT only for oligorecurrent disease. The most common primary tumors were lung and gastrointestinal cancer in 47 (33.1 %) and 28 (19.7 %) patients, respectively. After a median follow-up of 25 months, the median PFS and OS was 6.1 months and 48.9 months, respectively. Distant metastases were the most common first failure, and oligometastatic distant failure occured in 86 patients (60.6 %). New metastases were treated with repeat SBRT in 48 patients (33.8 %). The 1- and 2-year cumulative incidence of initiation of systemic therapy was 24.6 % and 36.8 %, respectively. In multivariable analysis, the number of previous lines of systemic therapy and the cumulative volume of metastases were significantly associated with the interval to initiation of systemic therapy. Conclusion: Selected patients with oligorecurrence achieved favorable OS and low cumulative incidence of initiation of systemic therapy. Prospective studies are warranted to determine how the deferral of systemic therapy impacts OS compared with immediate systemic therapy in combination with SBRT.

Purpose: Although radiation therapy (RT) is an effective and inexpensive pillar of multidisciplinary cancer care, access to RT facilities remains highly inequitable globally. Numerous studies have documented this resource gap, yet many countries continue facing their raging cancer epidemics ill-equipped. In this study, we present an estimation of resource deficits in low- and middle-income countries (LMICs) without any RT facilities at all. Methods and Materials: This study builds on publicly available data on country classification, population, cancer incidence, and RT requirements provided by the World Bank Group, the World Health Organization, and the International Atomic Energy Agency. Leveraging these data, we developed a capacity-planning model to estimate the current deficit of fundamental RT resources for LMICs with more than 1 million inhabitants and no active RT facilities. Results: There were 23 LMICs with a population of more than 1 million inhabitants and without any active RT facilities, 78% of which were located in sub-Saharan Africa. The aggregate population of these countries was 197.3 million people. The largest countries without RT facilities were Afghanistan and Malawi, with a population of 38.0 million and 18.6 million inhabitants, respectively. Estimated cancer incidence for all countries under study totaled at 134,783 new cases per year, 84,239 (62.5%) of which would have required RT. There was an aggregate deficit of 188 megavoltage machines and 85 brachytherapy afterloaders, along with simulation equipment and human capital in the magnitude of approximately 3363 trained radiation oncology staff. Conclusions: Hundreds of thousands of patients with cancer in LMICs continue to live in countries without access to RT in their own country. This extreme form of global health inequity requires urgent and decisive action, the success of which depends on the integration of international and local efforts.

Background and Introduction: Definitive surgical, oncological and radio-oncological treatment may result in significant morbidity and acute mortality. Mortality during or shortly after treatment in patients undergoing curative radio-(chemo)-therapy has not been studied systematically. We reviewed all curative radio-(chemo-)therapies at a large comprehensive cancer center over the last decade. Materials and Methods: The institutional record was screened for patients who received curative-intent radio-(chemo-)therapy and deceased during or within 30 days after radiotherapy. Curative therapy was defined as prescribed dosage of EQD2 ≥ 50 Gy for radiotherapy alone and EQD2 ≥ 40 Gy for radiochemotherapies. Data on demographics, disease and treatment were assembled and assessed. Results: Of 15,255 radiotherapy courses delivered at our center, 8,515 (56%) were performed with curative-intent. During or within 30 days after radio-(chemo-)therapy, 78 patients died (0.9% of all curative-intent courses). Median age of the deceased patients was 70 (IQR, 62–78) years, and 36% (28/78) were female. Median pre-therapeutic ECOG-PS was 1 (IQR, 0–2) and Charlson-Comorbidity-Index was 3+ (IQR, 2–3+). The most common primary malignancies were head and neck cancer (33/78; 42%) and central nervous system tumors (13/78; 17%). Peritherapeutic mortality varied by primary tumor, with the highest prevalence observed in head and neck and gastrointestinal cancer patients with 2.9% (33/1,144) and 2.4% (8/332), respectively. Among patients with known cause of death (34/78; 44%), tumor progression (12/34; 35%) and pulmonary complications/causes (11/34; 35%) were most common. On multivariable regression analysis, a worse ECOG-PS was associated with a relatively earlier peri-radiotherapeutic death (p = 0.014). Conclusion: Mortality during or within 30 days of curative-intent radio-(chemo-)therapy was low, yet highest for head and neck (2.9%) and gastrointestinal tumor (2.4%) patients. Reasons for these findings include rapid tumor progression in some cancers, good patient selection, with ECOG-PS being most useful and predictive for avoiding early mortality. Future research should help refine predictors for peri-RT mortality.

Background: Treatment of metastatic cancer patients with multiple repeat courses of radiotherapy has become more frequent due to their improved overall survival. However, very little is known about their long-term outcome. This analysis reports on the quality-of-life, hematologic toxicity, patient-reported experiences and satisfaction, and psychological distress of cancer patients treated with multiple repeat radiotherapy. Methods: All patients treated with ≥5 courses of radiotherapy between 2011 and 2019 at the Department of Radiation Oncology, University Hospital Zurich (USZ) were screened for this study. A course of radiotherapy was defined as all treatment sessions to one anatomical site under one medical indication. All patients completed two questionnaires: EORTC QLQ-C30 questionnaire for quality-of-life and a questionnaire evaluating psychological distress and patient-reported experiences. Hematologic toxicities were assessed via a recent blood sample. Results: Of n = 33 patients treated with ≥5 radiotherapy courses and being alive, 20 (60.6%) participated in this study. The most common primary tumor was non-small cell lung cancer (n = 14, 42.4%). The most common sites of irradiation were brain (n = 78, 37.1%) and bone metastases (n = 59, 28.1%). All participating patients reported that they had experienced a subjective benefit from multiple repeat radiotherapy and denied increased side effects in later radiotherapy courses. Yet, 45% (n = 9) of the patients reported an increase of psychological distress with increasing numbers of radiotherapy treatments. While global health status was stable, patients having received multiple repeat radiotherapy reported increased fatigue (p =

Introduction and background: Choosing the right treatment for the right patient in a setting of metastatic cancer disease remains a challenge. To facilitate clinical decision-making, predictive tools have been developed to personalize treatment. Here, we aim to assess the use of the recently proposed “METSSS score” as a prognostic tool for overall survival of cancer patients after palliative radiotherapy in the last phase of life. Methods: All patients treated with palliative radiotherapy at the end-of-life at the Department of Radiation Oncology of the University Hospital Zurich between January 2010 and December 2019 were included in this study. Data on demographics, diagnosis, treatment and comorbidities was extracted from the treatment planning and the electronical medical records system. To statistically assess the validity of the “METSSS score”, the mortality risk score was calculated, followed by stratification of all patients to prognostic risk groups. The prediction of the 1-year overall survival estimates was subsequently calculated. Results: Over the past decade, 274 patients have received palliative radiotherapy during the end-of-life period. One third of patients was female (34%, n = 93). The most frequent primary tumor was lung cancer (n = 121, 44%), and 55% of patients (n = 152) had no comorbidities according to the Charlson-Deyo comorbidity index. The most common radiotherapy site was the brain and eye region (42%, n = 115). The median actual overall survival of all patients was 40 days from the start of radiotherapy. The “METSSS score” survival model predicted that 269 patients (98.1%) belong into the high-risk, four patients (1.5%) into the medium-risk, and one patient (0.4%) into the low-risk group. The predicted median 1-year overall survival was 10%. Discussion: The METSSS score correctly predicted the survival of our end-of-life patient cohort by assigning them into the highest risk category, and it can therefore serve as a decision-making tool when assigning patient to symptomatic radiotherapy.

Abstract Introduction and background As cancer is developing into a chronic disease due to longer survival, continuity and coordination of oncological care are becoming more important for patients. As radiation oncology departments are an integral part of cancer care and as repeat irradiation becomes more commonplace, the relevance of continuity and coordination of care in operating procedures is increasing. This study aims to perform a single-institution analysis of cancer patients in which continuity and coordination of care matters most, namely the highly selected group with multiple repeat course radiotherapy throughout their chronic disease. Materials and methods All patients who received at least five courses of radiotherapy at the Department of Radiation Oncology at the University Hospital Zurich from 2011 to 2019 and who were alive at the time of the initiation of this project were included into this study. Patient and treatment characteristics were extracted from the hospital information and treatment planning systems. All patients completed two questionnaires on continuity of care, one of which was designed in-house and one of which was taken from the literature. Results Of the 33 patients identified at baseline, 20 (60.6%) participated in this study. A median of 6 years (range 3–13) elapsed between the first and the last visit at the cancer center. The median number of involved primary oncologists at the radiation oncology department was two (range 1–5). Fifty-seven percent of radiation therapy courses were preceded by a tumor board discussion. Both questionnaires showed high levels of experienced continuity of care. No statistically significant differences in experienced continuity of care between groups with more or less than two primary oncologists was found. Discussion and conclusion Patients treated with multiple repeat radiation therapy at our department over the past decade experienced high levels of continuity of care, yet further efforts should be undertaken to coordinate care among oncological disciplines in large cancer centers through better and increased use of interdisciplinary tumor boards.

Purpose: Our purpose was to assess the suitability of airway-implanted internal fiducial markers and an external surrogate of respiratory motion for motion management during radiation therapy of lung tumors. Methods and Materials: We analyzed 4-dimensional computed tomography scans acquired during radiation therapy simulation for 28 patients with lung tumors who had anchored fiducial markers bronchoscopically implanted inside small airways in or near the tumor in a prospective trial. We used a linear mixed model to build population-based correlative models of tumor and surrogate motion. The first 24 of the 28 patients were used to build correlative models, and 4 of the 28 consecutive patients were excluded and used as an internal validation cohort. Of the 24 patients from the model building cohort, all were used for the models based on the internal fiducial. The external surrogate was completely visualized in 11 patients from the model building cohort, so only those were used for the models based on the external surrogate. Furthermore, we determined the predicted residual error sum of squares for our correlative models, which may serve as benchmarks for future research. Results: The motion of the internal fiducials was significantly associated with the tumor motion in the anterior-posterior (P < .0001) and superior-inferior (SI) directions (P < .0001). We also observed a strong correlation of the external surrogate anterior-posterior motion to the tumor dominant SI motion (P < .0001). In the validation cohort, the internal fiducial SI motion was the only reliable predictor of lung tumor motion. Conclusions: The internal fiducials appear to be more reliable predictors of lung tumor motion than the external surrogate. The suitability of such airway-implanted internal fiducial markers for advanced motion management techniques should be further investigated. Although the external surrogate seems to be less reliable, its wide availability and noninvasive application support its clinical utility, albeit the greater uncertainty will need to be compensated for.