Dynamic fair balancing of COVID-19 patients over hospitals based on forecasts of bed occupancy.

This paper introduces mathematical models that support dynamic fair balancing of COVID-19 patients over hospitals in a region and across regions. Patient flow is captured in an infinite server queueing network. The dynamic fair balancing model within a region is a load balancing model incorporating a forecast of the bed occupancy, while across regions, it is a stochastic program taking into account scenarios of the future bed surpluses or shortages. Our dynamic fair balancing models yield decision rules for patient allocation to hospitals within the region and reallocation across regions based on safety levels and forecast bed surplus or bed shortage for each hospital or region. Input for the model is an accurate real-time forecast of the number of COVID-19 patients hospitalised in the ward and the Intensive Care Unit (ICU) of the hospitals based on the predicted inflow of patients, their Length of Stay and patient transfer probabilities among ward and ICU. The required data is obtained from the hospitals' data warehouses and regional infection data as recorded in the Netherlands. The algorithm is evaluated in Dutch regions for allocation of COVID-19 patients to hospitals within the region and reallocation across regions using data from the second COVID-19 peak.

Extra-abdominal desmoid tumor fibromatosis: a multicenter EMSOS study.

BACKGROUND: Extra-abdominal desmoid tumor fibromatosis (DTF) is a rare, locally aggressive soft tissue tumour. The best treatment modality for this patient cohort is still object of debate. QUESTIONS/PURPOSE: This paper aimed to (1) to compare the outcomes of DTF after different treatment modalities, (2) to assess prognostic factors for recurrence following surgical excision, and (3) to assess prognostic factors for progression during observation. METHODS: This was a retrospective multicenter study under the patronage of the European Musculoskeletal Oncology Society (EMSOS). All seven centres involved were tertiary referral centres for soft tissue tumours. Baseline demographic data was collected for all patients as well as data on the diagnosis, tumour characteristics, clinical features, treatment modalities and whether they had any predisposing factors for DTF. RESULTS: Three hundred eighty-eight patients (240 female, 140 male) with a mean age of 37.6 (±18.8 SD, range: 3-85) were included in the study. Two hundred fifty-seven patients (66%) underwent surgical excision of ADF, 70 patients (18%) were observed without therapy, the residual patients had different conservative treatments. There were no significant differences in terms of tumour recurrence or progression between the different treatment groups. After surgical excision, younger age, recurrent disease and larger tumour size were risk factors for recurrence, while tumours around the shoulder girdle and painful lesions were at risk of progression in the observational group. CONCLUSION: Local recurrence rate after surgery was similar to progression rates under observation. Hence, observation in DTF seems to be justified, considering surgery in case of dimensional progression in 2 consecutive controls (3 and 6 months) and in painful lesions, with particular attention to lesions around the shoulder girdle.

Real-time forecasting of COVID-19 bed occupancy in wards and Intensive Care Units.

This paper presents a mathematical model that provides a real-time forecast of the number of COVID-19 patients admitted to the ward and the Intensive Care Unit (ICU) of a hospital based on the predicted inflow of patients, their Length of Stay (LoS) in both the ward and the ICU as well as transfer of patients between the ward and the ICU. The data required for this forecast is obtained directly from the hospital's data warehouse. The resulting algorithm is tested on data from the first COVID-19 peak in the Netherlands, showing that the forecast is very accurate. The forecast may be visualised in real-time in the hospital's control centre and is used in several Dutch hospitals during the second COVID-19 peak.

Current concepts in the treatment of giant cell tumour of bone.

PURPOSE OF REVIEW: Giant cell tumour of bone (GCTB) is an intermediate, locally aggressive primary bone tumour. In addition to local therapy, new drugs became available for this disease. Denosumab, a receptor activator of nuclear factor κ-B-ligand inhibitor, was introduced as systemic targeted therapy for advanced or inoperable and metastatic GCTB. Also, the bisphosphonate zoledronic acid has activity in GCTB by directly targeting the neoplastic stromal cells. RECENT FINDINGS: In a small RCT, bisphosphonates were successful in controlling tumour growth and a higher apoptotic index of tumour cells was seen after zoledronic acid versus controls. Although bisphosphonate-loaded bone cement has not been studied to a large extent, it does not seem harmful and may constitute a logical local adjuvant. From the largest clinical trial to date, the risk-to-benefit ratio for denosumab in patients with advanced GCTB remains favourable, also in facilitating less morbid surgery. Concerns have arisen that recurrence rates would be higher than after conventional treatment, ranging from 20 to 100% in a systematic review, although this may be because of bias. H3F3A (G34W) driver mutations are helpful in the differentiation between GCTB and other giant cell-containing malignancies. H3.3-G34W proved sufficient to drive tumourigenesis. The cumulative incidence of malignancy in GCTB is estimated at 4%, of which primary malignancy 1.6% and secondary malignancy 2.4%, the latter mainly after radiation. To date, a potential causal relationship between denosumab and pulmonary metastases has not been confirmed; if they do not behave indolently, it would be advised to reassess diagnosis and consider malignancy. SUMMARY: Denosumab remains a highly effective treatment option for patients with advanced GCTB. A short duration of 2-4 months neoadjuvant denosumab is advised to facilitate less morbid surgery and prevent incomplete curettage by macroscopic tumour alterations. Reduced dose intensity is being studied to reduce long term side-effects. Further research on bisphosphonates and other targets including H3.3-G34W remains warranted.

Patients With Isolated Craniofacial Dysplasia Report Better Quality of Life Compared With Those With Craniofacial Dysplasia and Extracranial Involvement.

PURPOSE: Craniofacial fibrous dysplasia (CFD) is a subtype of fibrous dysplasia/McCune-Albright syndrome (FD/MAS) characterized by FD lesions in one or more of the skull bones. The orbit is often involved, with facial pain, facial deformity, and increased risk of compressive optic neuropathy as associated clinical manifestations possibly leading to altered illness perceptions and impairments in quality of life(QoL). The aim of this study was to evaluate illness perceptions and QoL in patients with CFD among our FD/MAS cohort. METHODS: One hundred ninety-one patients were included. Illness perceptions and QoL were assessed by using validated questionnaires, that is, the Illness Perceptions Questionnaire-Revised and the Short-Form 36. Patients were first grouped as CFD versus non-CFD, a second selection was based on the presence of "Isolated CFD" versus "CFD+PFD/MAS." Non-CFD patients were grouped as monostotic fibrous dysplasia "MFD" versus polyostotic "PFD/MAS." RESULTS: Patients with isolated CFD attributed less symptoms to their disease compared with patients with CFD+PFD/MAS (p < 0.05). Furthermore, patients with isolated CFD reported better QoL on all domains (except role emotional and mental health) compared with patients with CFD+PFD/MAS (p < 0.05). Patients with isolated CFD also reported better QoL compared with non-CFD groups (on 3 out of 8 subscales) (p < 0.05). CONCLUSIONS: Patients with isolated CFD attribute less symptoms to their disease and report better QoL compared with patients with CFD with extracranial involvement or FD without cranial involvement. These findings indicate that craniofacial involvement alone is not sufficient to cause negative illness perceptions and impairments in QoL. Therefore, it can be postulated that isolated CFD should be considered a unique patient subtype within the spectrum of FD/MAS patients.

Adjuvant Zoledronic Acid in High-Risk Giant Cell Tumor of Bone: A Multicenter Randomized Phase II Trial.

LESSONS LEARNED: Adjuvant treatment with zoledronic acid did not decrease the recurrence rate of giant cell tumor of bone (GCTB) in this study. The efficacy could not be determined because of the small sample size.GCTB recurrences, even in the denosumab era, are still an issue; therefore, a randomized study exploring the efficacy of zoledronic acid in the adjuvant setting in GCTB is still valid. BACKGROUND: Bisphosphonates are assumed to inhibit giant cell tumor of bone (GCTB)-associated osteoclast activity and have an apoptotic effect on the neoplastic mononuclear cell population. The primary objective of this study was to determine the 2-year recurrence rate of high-risk GCTB after adjuvant zoledronic acid versus standard care. METHODS: In this multicenter randomized open-label phase II trial, patients with high-risk GCTB were included (December 2008 to October 2013). Recruitment was stopped because of low accrual after the introduction of denosumab. In the intervention group, patients received adjuvant zoledronic acid (4 mg) intravenously at 1, 2, 3, 6, 9, and 12 months after surgery. RESULTS: Fourteen patients were included (intervention n = 8, controls n = 6). Median follow-up was long: 93.5 months (range, 48-111). Overall 2-year recurrence rate was 38% (3/8) in the intervention versus 17% (1/6) in the control group (p = .58). All recurrences were seen within the first 15 months after surgery. CONCLUSION: Adjuvant treatment with zoledronic acid did not decrease the recurrence rate of GCTB in this study. The efficacy could not be determined because of the small sample size. Because recurrences, even in the denosumab era, are still an issue, a randomized study exploring the efficacy of zoledronic acid in the adjuvant setting in GCTB is still valid.

Challenges of denosumab in giant cell tumor of bone, and other giant cell-rich tumors of bone.

PURPOSE OF REVIEW: Giant cell tumor of bone (GCTB) is an uncommon benign primary bone tumor, consisting of receptor activator of nuclear factor kappa-B (RANK) expressing reactive osteoclast-like giant cells and neoplastic spindle-shaped cells. Denosumab was approved by FDA in 2013 and by EMA in 2014 to treat adults and skeletally mature adolescents with unresectable GCTB or when resection is likely to result in severe morbidity. However, there is much discussion regarding the optimal applied treatment strategy. RECENT FINDINGS: Neoadjuvant treatment of GCTB with denosumab can effectively downstage tumors to facilitate less morbid surgery or completely avoid the need for resection, but there is concern about local recurrence postsurgery. Definitive treatment of unresectable GTCB improves symptoms and halts tumor progression. The optimal treatment duration is unclear and long-term treatment is associated with adverse events like osteonecrosis of the jaw (ONJ) and atypical femoral fractures. Denosumab maintenance dose interval is currently being investigated. SUMMARY: For the related but heterogenous group of giant cell rich tumors of bone, like aneurysmal bone cysts (ABC) and central giant cell granuloma (CGCG), denosumab is a new treatment modality under investigation. Given the effectiveness in GCTB, this could be a promising treatment option for selected patients with advanced disease.

Ribbing disease: a systematic review.

Background Ribbing disease, or multiple diaphyseal sclerosis, is a rare benign bone dysplasia. Purpose To systematically review the literature to determine the clinical and radiological presentation of patients with Ribbing disease as well as the effects of attempted treatments. Material and Methods We considered individual patient data of patients diagnosed with Ribbing disease derived from patient reports and patient series. All stages of the review were performed by two reviewers independently. Standard descriptive statistics were used for quantitative analyses and mixed model analyses were used when appropriate Results The literature search yielded 420 unique hits of which 23 studies were included, covering a total of 40 patients of whom 29 had bilateral involvement. The mean age at diagnosis was 35 years and the mean time between diagnosis and onset of symptoms, mostly pain, was five years (range = 1-16 years). The tibial diaphysis was the most commonly involved bone in 35 of 36 patients. Non-surgical treatment consisted of non-steroidal anti-inflammatory drugs (NSAIDs), prednisone, and bisphophonates with mixed results. Surgical treatment consisted of intramedullary reaming and fenestration and was very effective to reduce pain. Conclusion The clinical presentation and imaging findings of patients with Ribbing disease are becoming more apparent. However, there is paucity of evidence on the natural disease progression and effectiveness of treatment modalities.

Tailored Beta-catenin mutational approach in extra-abdominal sporadic desmoid tumor patients without therapeutic intervention.

BACKGROUND: The efficacy of the classical treatment modalities surgery and radiotherapy in the treatment of aggressive fibromatosis is presently disputed and there is a shift towards a more conservative approach. The aim of the present study is to objectify tumor growth in patients with extra-abdominal or abdominal wall aggressive fibromatosis, while adhering to a "watchful waiting" policy. Other objectives are to investigate quality of life and to identify factors associated with tumor growth, in particular the relation with the presence of a CTNNB1-gene mutation in the tumor. DESIGN AND METHODS: GRAFITI is a nationwide, multicenter, prospective registration trial. All patients with extra-abdominal or abdominal wall aggressive fibromatosis are eligible for inclusion in the study. Main exclusion criteria are: history of familiar adenomatous polyposis, severe pain, functional impairment, life/limb threating situations in case of progressive disease. Patients included in the study will be treated with a watchful waiting policy during a period of 5 years. Imaging studies with ultrasound and magnetic resonance imaging scan will be performed during follow-up to monitor possible growth: the first years every 3 months, the second year twice and the yearly. In addition patients will be asked to complete a quality of life questionnaire on specific follow-up moments. The primary endpoint is the rate of progression per year, defined by the Response Evaluation Criteria In Solid Tumors (RECIST). Secondary endpoints are quality of life and the rate of influence on tumor progression for several factors, such as CTNNB1-mutations, age and localization. DISCUSSION: This study will provide insight in tumor behavior, the effect on quality of life and clinicopathological factors predictive of tumor progression. TRIAL REGISTRATION: The GRAFITI trial is registered in the Netherlands National Trial Register (NTR), number 4714 .

Surgical downstaging in an open-label phase II trial of denosumab in patients with giant cell tumor of bone.

BACKGROUND: Surgical resection with curative intent for giant cell tumor of bone (GCTB) may be associated with severe morbidity. This interim analysis evaluated reduction in surgical invasiveness after denosumab treatment in patients with resectable GCTB. METHODS: Patients with primary or recurrent GCTB, for whom the initially planned surgery was associated with functional compromise or morbidity, received denosumab 120 mg subcutaneously every 4 weeks (additional doses on days 8 and 15 of the first cycle). Planned and actual GCTB-related surgical procedures before and after denosumab treatment were reported. Patients were followed for surgical outcome, adverse events, and recurrence following resection. RESULTS: Overall, 222 patients were evaluable for surgical downstaging (54 % were women; median age 34 years). Lesions (67 % primary and 33 % recurrent) were located in the axial (15 %) and appendicular skeleton (85 %). At the data cutoff date, most patients had not yet undergone surgery (n = 106; 48 %) or had a less morbid procedure (n = 84; 38 %) than originally planned. Median (interquartile range) time on denosumab was 19.5 (12.4-28.6) months for the 106 patients who had not undergone surgery and were continuing on monthly denosumab. Native joint preservation was 96 % (n = 24/25) for patients with planned joint/prosthesis replacement and 86 % (n = 30/35) for patients with planned joint resection/fusion. Of the 116 patients who had surgery (median postsurgical follow-up 13.0 [8.5-17.9] months), local recurrence occurred in 17 (15 %) patients. CONCLUSION: For patients with resectable GCTB, neoadjuvant denosumab therapy resulted in beneficial surgical downstaging, including either no surgery or a less morbid surgical procedure.

Hyperplasia of rib and vertebra, associated with infiltrating lipoma: a rare case of focal overgrowth.

PURPOSE: Syndromes with focal overgrowth are rare and diagnosis is difficult because manifestations are highly variable and symptoms overlap between syndromes. Diagnosis depends on clinical history, physical examination, and radiologic and histologic findings. This report describes a case of focal overgrowth of the left seventh rib and half of the adjacent thoracic vertebra, with overlying infiltrating lipoma. METHODS: A 13-year-old boy presented with an asymptomatic chest wall mass caused by enlargement of the seventh rib and an overlying soft-tissue mass accompanied by enlargement of half of the seventh thoracic vertebra. MRI showed infiltration of lipomatous tissue in the muscles, but no interfascicular accumulation of adipose tissue in the thoracic spinal nerve. RESULTS: A similar case was presented in 1985 but without MR imaging. CONCLUSION: We report on a second case of focal overgrowth of a rib and half of the adjacent vertebra, and overlying lipoma. In addition to the first case, we present MR images demonstrating infiltration of the adipose tissue.

High-grade soft tissue sarcomas of the extremities: surgical margins influence only local recurrence not overall survival.

PURPOSE: After surgical treatment of high-grade soft tissue sarcomas, local recurrences, metastases and survival remain a great concern. Further knowledge on factors with a possible impact on these endpoints, specifically resection margins, is relevant for decision-making regarding the aggressiveness of local treatment. The aim of this study is to investigate the impact of prognostic factors on local recurrence and overall survival for patients with high-grade soft tissue sarcomas of the extremities. METHODS: In a retrospective cohort study of 127 patients (mean age 48 years, range five to 91; median follow-up 71 months) the prognostic effect of margin status and other clinicopathologic characteristics on local recurrence and overall survival were analysed by employing a multivariate Cox regression. RESULTS: Five-year cumulative incidence of local recurrence and distant metastases was 26% and 40%, respectively. The estimated five-year overall survival was 59%. Tumour size proved a consistent adverse prognostic factor for local recurrence (hazard ratio (HR) 3.9), distant metastasis (HR 4.9) and overall survival (HR 2.4). The significant association of resection margins with local recurrence (HR 10.2) was confirmed. Margins were however not significantly associated with the occurrence of distant metastasis or overall survival. The occurrence of local recurrence had a significant impact on overall survival (HR 2.0). CONCLUSIONS: The results of this study confirm the critical role of tumour size on survival and margins on local recurrence, and stress the need for further investigation concerning the association between margins, local recurrence and survival.

Outcome of advanced, unresectable conventional central chondrosarcoma.

BACKGROUND: For patients who have chondrosarcoma with unresectable disease, because of tumor location, tumor size, or extensive metastatic disease, treatment options are very limited because of their relative resistance to radiotherapy and chemotherapy. The overall survival of this patient population is poor; however, specific studies are lacking, and large series have not been published. Therefore, the authors conducted this retrospective, 2-center study to gain insight into the outcome of patients with advanced, unresectable, conventional central chondrosarcoma. METHODS: All patients with unresectable conventional central chondrosarcoma who were diagnosed between January 1, 1980 and December 31, 2011 in 2 major European bone sarcoma centers (Rizzoli Institute, Bologna, Italy and Leiden University Medical Center, Leiden, the Netherlands) were selected. Relevant information was collected from the medical records at both centers. RESULTS: In total, 171 patients met the selection criteria. The overall survival rate for all patients was 48% at 1 year, 24% at 2 years, 12% at 3 years, 6% at 4 years, and 2% at 5 years. Patients with unresectable, locally advanced disease without distant metastases had a significantly better survival than patients with metastatic disease (P = .0014). Systemic treatment, consisting of either doxorubicin-based chemotherapy or the noncytotoxic drugs imatinib and sirolimus, improved survival significantly compared with no treatment (P = .0487). For patients who had locally advanced disease without metastases, radiotherapy was associated with a survival benefit (P = .0032). CONCLUSIONS: This study provides a standard for overall survival rates after a diagnosis of unresectable conventional central chondrosarcoma. Systemic treatment and radiotherapy may improve survival, although selection bias because of the retrospective nature of this study may have influenced the outcome. The poor survival underlines the need for new therapeutic options for this patient population. Cancer 2014;120:3159-3164. © 2014 American Cancer Society.

Limited waiting areas in outpatient clinics: an intervention to incorporate the effect of bridging times in blueprint schedules.

BACKGROUND: Distancing measures enforced by the COVID-19 pandemic impose a restriction on the number of patients simultaneously present in hospital waiting areas. OBJECTIVE: Evaluate waiting area occupancy of an intervention that designs clinic blueprint schedules, in which all appointments of the pre-COVID-19 case mix are scheduled either digitally or in person under COVID-19 distancing measures, whereby the number of in-person appointments is maximised. METHODS: Preintervention analysis and prospective assessment of intervention outcomes were used to evaluate the outcomes on waiting area occupancy and number of in-person consultations (postintervention only) using descriptive statistics, for two settings in the Rheumatology Clinic of Sint Maartenskliniek (SMK) and Medical Oncology & Haematology Outpatient Clinic of University Medical Center Utrecht (UMCU). Retrospective data from October 2019 to February 2020 were used to evaluate the pre-COVID-19 blueprint schedules. An iterative optimisation and simulation approach was followed, based on integer linear programming and Monte Carlo simulation, which iteratively optimised and evaluated blueprint schedules until the 95% CI of the number of patients in the waiting area did not exceed available capacity. RESULTS: Under pre-COVID-19 blueprint schedules, waiting areas would be overcrowded by up to 22 (SMK) and 11 (UMCU) patients, given the COVID-19 distancing measures. The postintervention blueprint scheduled all appointments without overcrowding the waiting areas, of which 88% and 87% were in person and 12% and 13% were digitally (SMK and UMCU, respectively). CONCLUSIONS: The intervention was effective in two case studies with different waiting area characteristics and a varying number of interdependent patient trajectory stages. The intervention is generically applicable to a wide range of healthcare services that schedule a (series of) appointment(s) for their patients. Care providers can use the intervention to evaluate overcrowding of waiting area(s) and design optimal blueprint schedules to continue a maximum number of in-person appointments under pandemic distancing measures.

Single-institution clinical experience using robust intensity modulated proton therapy in chordoma and chondrosarcoma of the mobile spine and sacrum: Feasibility and need for plan adaptation.

BACKGROUND: Due to its specific physical characteristics, proton irradiation is especially suited for irradiation of chordomas and chondrosarcoma in the axial skeleton. Robust plan optimization renders the proton beam therapy more predictable upon individual setup errors. Reported experience with the planning and delivery of robustly optimized plans in chordoma and chondrosarcoma of the mobile spine and sacrum, is limited. In this study, we report on the clinical use of robustly optimized, intensity modulated proton beam therapy in these patients. METHODS: We retrospectively reviewed patient, treatment and acute toxicity data of all patients with chordoma and chondrosarcoma of the mobile spine and sacrum, treated between 1 April 2019 and 1 April 2020 at our institute. Anatomy changes during treatment were evaluated by weekly cone-beam CTs (CBCT), supplemented by scheduled control-CTs or ad-hoc control-CTs. Acute toxicity was scored weekly during treatment and at 3 months after therapy according to CTCAE 4.0. RESULTS: 17 chordoma and 3 chondrosarcoma patients were included. Coverage of the high dose clinical target volume was 99.8% (range 56.1-100%) in the nominal and 80.9% (range 14.3-99.6%) in the voxel-wise minimum dose distribution. Treatment plan adaptation was needed in 5 out of 22 (22.7%) plans. Reasons for plan adaptation were either reduced tumor coverage or increased dose to the OAR. CONCLUSIONS: Robustly optimized intensity modulated proton beam therapy for chordoma and chondrosarcoma of the mobile spine is feasible. Plan adaptations due to anatomical changes were required in approximately 23 percent of treatment courses.

No haploinsufficiency but loss of heterozygosity for EXT in multiple osteochondromas.

Multiple osteochondromas (MO) is an autosomal dominant disorder caused by germline mutations in EXT1 and/or EXT2. In contrast, solitary osteochondroma (SO) is nonhereditary. Products of the EXT gene are involved in heparan sulfate (HS) biosynthesis. In this study, we investigated whether osteochondromas arise via either loss of heterozygosity (2 hits) or haploinsufficiency. An in vitro three-dimensional chondrogenic pellet model was used to compare heterozygous bone marrow-derived mesenchymal stem cells (MSCs EXT(wt/-)) of MO patients with normal MSCs and the corresponding tumor specimens (presumed EXT(-/-)). We demonstrated a second hit in EXT in five of eight osteochondromas. HS chain length and structure, in vitro chondrogenesis, and EXT expression levels were identical in both EXT(wt/-) and normal MSCs. Immunohistochemistry for HS, HS proteoglycans, and HS-dependent signaling pathways (eg, TGF-ß/BMP, Wnt, and PTHLH) also showed no differences. The cartilaginous cap of osteochondroma contained a mixture of HS-positive and HS-negative cells. Because a heterozygous EXT mutation does not affect chondrogenesis, EXT, HS, or downstream signaling pathways in MSCs, our results refute the haploinsufficiency theory. We found a second hit in 63% of analyzed osteochondromas, supporting the hypothesis that osteochondromas arise via loss of heterozygosity. The detection of the second hit may depend on the ratio of HS-positive (normal) versus HS-negative (mutated) cells in the cartilaginous cap of the osteochondroma.

Clinical Outcome of Surgically Treated Leiomyosarcoma of the Extremities: A Retrospective Overview.

AIM: This study was interested in extremity leiomyosarcoma with focus on clinical outcome after surgery with or without adjuvant therapy. PATIENTS AND METHODS: A retrospective case series of all patients with leiomyosarcoma, surgically treated between 2000 and 2015 and a minimum follow-up of 2 years, was drawn from institutional databases in Belgium and the Netherlands. Postoperative complications were reported with the Radiation Therapy Oncology Group (RTOG) and the Henderson classification. RESULTS: Seventy-five patients were operated on, of whom 47 underwent (neo)adjuvant therapy. Infection was observed in 11 patients, seven associated with (neo)adjuvant radiotherapy. Dermatological complaints were observed in 26 patients, 10 associated with (neo)adjuvant radiotherapy. Overall survival was 60%. Local recurrence occurred in 11 (15%) patients. CONCLUSION: This study describes favourable clinical outcome following (neo)adjuvant radiotherapy. In the future, larger databases on leiomyosarcoma should enhance the power of these findings and define the benefits of adjuvant therapy in leiomyosarcoma.

Patient-specific finite element computer models improve fracture risk assessments in cancer patients with femoral bone metastases compared to clinical guidelines.

PURPOSE: To determine whether patient-specific finite element (FE) computer models are better at assessing fracture risk for femoral bone metastases compared to clinical assessments based on axial cortical involvement on conventional radiographs, as described in current clinical guidelines. METHODS: Forty-five patients with 50 femoral bone metastases, who were treated with palliative radiotherapy for pain, were included (64% single fraction (8Gy), 36% multiple fractions (5 or 6x4Gy)) and were followed for six months to determine whether they developed a pathological femoral fracture. All plain radiographs available within a two month period prior to radiotherapy were obtained. Patient-specific FE models were constructed based on the geometry and bone density obtained from the baseline quantitative CT scans used for radiotherapy planning. Femoral failure loads normalized for body weight (BW) were calculated. Patients with a failure load of 7.5 x BW or lower were identified as having high fracture risk, whereas patients with a failure load higher than 7.5 x BW were classified as low fracture risk. Experienced assessors measured axial cortical involvement on conventional radiographs. Following clinical guidelines, patients with lesions larger than 30mm were identified as having a high fracture risk. FE predictions were compared to clinical assessments by means of diagnostic accuracy values (sensitivity, specificity and positive (PPV) and negative predictive values (NPV)). RESULTS: Seven femurs (14%) fractured during follow-up. Median time to fracture was 8 weeks. FE models were better at assessing fracture risk in comparison to axial cortical involvement (sensitivity 100% vs. 86%, specificity 74% vs. 42%, PPV 39% vs. 19%, and NPV 100% vs. 95%, for the FE computer model vs. axial cortical involvement, respectively). CONCLUSIONS: Patient-specific FE computer models improve fracture risk assessments of femoral bone metastases in advanced cancer patients compared to clinical assessments based on axial cortical involvement, which is currently used in clinical guidelines.

Prevalence and Clinical Features of Mazabraud Syndrome: A Multicenter European Study.

BACKGROUND: Mazabraud syndrome is a rare disorder, characterized by the presence of fibrous dysplasia (FD) with associated intramuscular myxomas. Data are scarce on the prevalence, clinical features, and natural history of this disorder and outcomes. In this multicenter study, we evaluated a series of patients from 6 European centers. METHODS: All centers affiliated with the European Musculo-Skeletal Oncology Society (EMSOS) were invited to include data on all patients with Mazabraud syndrome who were seen between 1980 and 2015. The study investigated the prevalence of Mazabraud syndrome, the type, severity, and localization of FD lesions in relation to myxomas, the histopathology of myxomas, and results of GNAS-mutation analysis, when available. RESULTS: Thirty-two patients (22 female) from 6 centers were included. The prevalence of Mazabraud syndrome was 2.2% in the combined cohort of 1,446 patients with FD, and the syndrome was diagnosed at a mean of 10.1 years after diagnosis of FD. The myxomas were predominantly localized in the upper leg. Excision was performed in 20 patients, recurrence occurred in 6 of these patients (30%) at a median of 8.5 years (range, 1.9 to 16.0 years), and revision surgery was necessary in 5 (25%). High cellularity of myxomas was associated with recurrence (p < 0.05). A GNAS mutation was identified in the myxoma tissue of 5 (83%) of 6 patients with GNAS-mutation analysis. CONCLUSIONS: This study is the first, to our knowledge, to provide data on the prevalence of Mazabraud syndrome in a relatively large cohort. Although the outcomes of surgical resection were good, a quarter of the patients required revision surgery despite clear resection margins. High cellularity of myxomas was associated with recurrence. GNAS mutations were identified in 83% (5 of 6), emphasizing the shared origin of FD and myxomas. Our data show that patients with FD who have disproportionate complaints, irrespective of FD type, extent, or severity, should be investigated for the possible presence of myxomas. LEVEL OF EVIDENCE: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Individualizing Follow-Up Strategies in High-Grade Soft Tissue Sarcoma with Flexible Parametric Competing Risk Regression Models.

Currently, patients with extremity soft tissue sarcoma (eSTS) who have undergone curative resection are followed up by a heuristic approach, not covering individual patient risks. The aim of this study was to develop two flexible parametric competing risk regression models (FPCRRMs) for local recurrence (LR) and distant metastasis (DM), aiming at providing guidance on how to individually follow-up patients. Three thousand sixteen patients (1931 test, 1085 validation cohort) with high-grade eSTS were included in this retrospective, multicenter study. Histology (9 categories), grading (time-varying covariate), gender, age, tumor size, margins, (neo)adjuvant radiotherapy (RTX), and neoadjuvant chemotherapy (CTX) were used in the FPCRRMs and performance tested with Harrell-C-index. Median follow-up was 50 months (interquartile range: 23.3-95 months). Two hundred forty-two (12.5%) and 603 (31.2%) of test cohort patients developed LR and DM. Factors significantly associated with LR were gender, size, histology, neo- and adjuvant RTX, and margins. Parameters associated with DM were margins, grading, gender, size, histology, and neoadjuvant RTX. C-statistics was computed for internal (C-index for LR: 0.705, for DM: 0.723) and external cohort (C-index for LR: 0.683, for DM: 0.772). Depending on clinical, pathological, and patient-related parameters, LR- and DM-risks vary. With the present model, implemented in the updated Personalised Sarcoma Care (PERSARC)-app, more individualized prediction of LR/DM-risks is made possible.