Limited Number Of Series Research Articles

Particle Radiotherapy for Skull Base Chondrosarcoma: A Clinical Series from Italian National Center for Oncological Hadrontherapy.

Simple SummarySkull-base chondrosarcoma is a rare locally aggressive or malignant group of cartilaginous neoplasm. The standard of care consists of surgery and high-dose radiation therapy, better if with particle, due to their radioresistance and proximity to organs at risk such as brainstem and optic pathways. Due to the rarity of the tumor and its site, outcomes in terms of local control and toxicity of patients with this malignancy after receiving particle therapy has been documented only in a limited number of series with a restricted number of patients, in particular with regard to carbon ions. The aim of our retrospective study is to assess the role of particle therapy (protons and carbon ions) after surgery in our Institute in skull-base chondrosarcomas. Background: The standard treatment for skull base chondrosarcoma (SB-CHS) consists of surgery and high-dose radiation therapy. Our aim was to evaluate outcome in terms of local control (LC) and toxicity of proton therapy (PT) and carbon ion (CIRT) after surgery. Materials and methods: From September 2011 to July 2020, 48 patients underwent particle therapy (67% PT, 33% CIRT) for SB-CHS. PT and CIRT total dose was 70 GyRBE (relative biological effectiveness) in 35 fractions and 70.4 GyRBE in 16 fractions, respectively. Toxicity was assessed using the Common Terminology Criteria for Adverse Events (CTCAE v5). Results: After a median follow-up time of 38 months, one local failure (2%) was documented and the patient died for progressive disease. Overall, 3-year LC was 98%. One (2%) and 4 (8%) patients experienced G3 acute and late toxicity, respectively. White-matter brain changes were documented in 22 (46%) patients, but only 7 needed steroids (G2). No patients had G3 brain toxicity. No G4–5 complications were reported. We did not find any correlation between high-grade toxicity or white-matter changes and characteristics of patients, disease and surgery. Conclusions: PT and CIRT appeared to be effective and safe treatments for patients with SB-CHS, resulting in high LC rates and an acceptable toxicity profile.

Révision isolée de la cupule acétabulaire par chirurgie assistée par ordinateur

BackgroundIn isolated acetabular revision surgery, surgeons must place the cup at an appropriate angle with various retained stem anteversion angles to prevent postoperative dislocation. For accurate acetabular cup position, various navigation systems have been used. Nevertheless, no publications have reported combined cup and stem anteversion and dislocation rates after isolated acetabular revision, especially comparing the use of navigation with manual implantation. Therefore we performed a retrospective comparative study to answer the following questions: 1) What is the combined anteversion after isolated acetabular revision with computed tomography-based navigation? 2) Does navigation improve the accuracy of cup angle and combined anteversion, 3) reduce dislocation rate, and 4) reduce operative time? HypothesisA navigation system makes combined anteversion near the target angle in isolated acetabular revision. Patients and methodsWe conducted a retrospective study of 32 hips in 24 patients who underwent isolated acetabular revision total hip arthroplasty using computed tomography-based navigation system. The control group comprised 8 hips in 8 patients who underwent the same procedure without navigation. ResultsIn the navigation group, average Widmer's combined anteversion was 39.0±8.7 (range, 25.3–56.6). Cup positions were 40.3±2.9 (range, 29.0–49.0) for radiographic abduction angle, 24.3±8.0 (range, 4.6–42.6) for radiographic anteversion. In the control group, Widmer's combined anteversion was 47.2±15.1 (range, 27.0–74.3, p=0.048). The average cup positions for radiographic abduction angle and anteversion were 36.7±8.9 (range, 24.5–54.9) and 29.1±7.3 (range, 17.2–38.8), respectively (p>0.05). Widmer's combined anteversion deviated from the target angle by a smaller amount in the navigation group than in the control group: errors in measurement of Widmer's combined anteversion were 7.2±5.1 (range, 0.74–19.6) in the navigation group and 13.9±11.1 (range, 3.6–37.3) in the control group (p=0.135). Postoperative dislocation occurred in none of the 32 hips (0%) in the navigation group and in one of the 8 hips (12.5%) in the control group (p=0.2). DiscussionUsing the navigation system, combined anteversion is made near the target angle in isolated acetabular revision surgery and more accurately than manual implantation. These results should be considered as preliminary since this is a limited cohort, but it brings new knowledge in navigation considering the very limited number of series using of navigation in isolated cup revision of total hip arthroplasty. In addition, this is the first study to investigate combined cup and stem anteversion in isolated acetabular revision. The use of CT-scan is helpful to diagnose error in stem anteversion and to adapt the orientation of the new cup. Level of evidenceIII, retrospective case control study.

Isolated acetabular revision with femoral stem retention using computed tomography-based navigation

BackgroundIn isolated acetabular revision surgery, surgeons must place the cup at an appropriate angle with various retained stem anteversion angles to prevent postoperative dislocation. For accurate acetabular cup position, various navigation systems have been used. Nevertheless, no publications have reported combined cup and stem anteversion and dislocation rates after isolated acetabular revision, especially comparing the use of navigation with manual implantation. Therefore we performed a retrospective comparative study to answer the following questions: (1) What is the combined anteversion after isolated acetabular revision with computed tomography-based navigation? (2) Does navigation improve the accuracy of cup angle and combined anteversion, (3) reduce dislocation rate, and (4) reduce operative time? HypothesisA navigation system makes combined anteversion near the target angle in isolated acetabular revision. Patients and methodsWe conducted a retrospective study of 32 hips in 24 patients who underwent isolated acetabular revision total hip arthroplasty using computed tomography-based navigation system. The control group comprised 8 hips in 8 patients who underwent the same procedure without navigation. ResultsIn the navigation group, average Widmer's combined anteversion was 39.0°±8.7° (range, 25.3°–56.6°). Cup positions were 40.3°±2.9° (range, 29.0°–49.0°) for radiographic abduction angle, 24.3°±8.0° (range, 4.6°–42.6°) for radiographic anteversion. In the control group, Widmer's combined anteversion was 47.2°±15.1° (range, 27.0°–74.3°, p=0.048). The average cup positions for radiographic abduction angle and anteversion were 36.7°±8.9° (range, 24.5°–54.9°) and 29.1°±7.3° (range, 17.2°–38.8°), respectively (p>0.05). Widmer's combined anteversion deviated from the target angle by a smaller amount in the navigation group than in the control group: errors in measurement of Widmer's combined anteversion were 7.2°±5.1° (range, 0.74°–19.6°) in the navigation group and 13.9°±11.1° (range, 3.6°–37.3°) in the control group (p=0.135). Postoperative dislocation occurred in none of the 32 hips (0%) in the navigation group and in one of the 8 hips (12.5%) in the control group (p=0.2). DiscussionUsing the navigation system, combined anteversion is made near the target angle in isolated acetabular revision surgery and more accurately than manual implantation. These results should be considered as preliminary since this is a limited cohort, but it brings new knowledge in navigation considering the very limited number of series using of navigation in isolated cup revision of total hip arthroplasty. In addition this is the first study to investigate combined cup and stem anteversion in isolated acetabular revision. The use of CT-scan is helpful to diagnose error in stem anteversion and to adapt the orientation of the new cup. Level of evidenceIII, Retrospective case control study.

Long term outcome of skull-base chondrosarcoma patients treated with high-dose proton therapy with or without conventional radiation therapy

Background and purposeSkull-base chondrosarcoma (ChSa) is a rare bone tumor and the outcome of patients with this malignancy has been documented only in a limited number of series with a restricted number of patients. ObjectiveThis study was conducted to assess the outcome and prognostic factors of a large cohort of ChSa patients treated with radiotherapy in two proton therapy centers. Materials and methodsFrom 1996 to 2015, 251 (male, 43.4%) patients (mean age, 42.0 ± 16.2 years) were treated with protons with (n = 135; 53.8%) or without photons (n = 116; 46.2%). Median delivered dose was 70.2 GyRBE. Failure-free survival (FFS), overall survival (OS) and CTCAE grade ≥3 toxicity free survival (TFS) were calculated using the Kaplan–Meier method. ResultsAfter a median follow-up of 88.0 months for surviving patients, local and distant failures were observed in 12 (4.8%) and 4 (1.6%) patients, respectively. Late failures >6 years were observed in 4 (33.3%) patients. The estimated 7-year FFS was 93.1%. Twenty-five (10%) patients died. The estimated 7-year OS was 93.6%. Tumor volume (p = 0.006) and optic pathway compression (p = 0.027) were significantly associated with the risk of treatment failure on univariate analysis. Treatment failure was significantly associated with a higher risk of death (hazard ratio = 126). The estimated 7-year TFS was 84.2%. ConclusionsThe outcome of skull-base ChSa patients treated with high-dose protons with or without photons is excellent, particularly for patients with small tumors with no optic pathway compression. Treatment failure was however associated with a significantly increased risk of death.

Do mountain hare populations cycle?

We investigated the occurrence and distribution of multi‐annual cycles in abundance of mountain hare populations across a wide area of their range in northern Europe. We analysed 125 time‐series of mountain hare abundance indexed from hunting bag records and questionnaire responses from Scotland, Sweden, Finland and Switzerland. We also reanalysed 17 previously published time‐series based on hunting bag records and snow track indices from mountain hare populations in Scotland, Norway, Sweden, Finland, Russia and Italy. Autocorrelation analysis showed that 45% of mountain hare populations showed evidence of cycles, characterised by significant negative autocorrelations at half or the whole cycle period. The amplitude and periodicity of cycles varied between and within countries. Time‐series in Scotland were characterised by high‐amplitude weak cycles with a mean periodicity of nine years but with a range of 4–15 years. Norwegian and Swedish time‐series revealed low amplitude weak cycles with a 3–7 year period. Finnish time‐series showed low amplitude cycles with a 4–11 year period. Alpine time‐series were predominantly non‐cyclic, while the limited number of series from Russia showed high amplitude weak cycles with an 8–11 year period. The results reveal that mountain hare populations show a wide range of population dynamics with distinct regional differences in periodicity, amplitude and density dependent structure of cycles. These findings suggest that different factors may limit or regulate mountain hare populations in different regions of Europe thus supporting the results of recent field studies.

Interpolation and backdating with a large information set

Existing methods for data interpolation or backdating are either univariate or based on a very limited number of series, due to data and computing constraints that were binding until the recent past. Nowadays large datasets are readily available, and models with hundreds of parameters are easily estimated. We model these large datasets with a factor model, and develop an interpolation method that exploits the estimated factors as an efficient summary of all available information. The method is compared with existing standard approaches from a theoretical point of view, by means of Monte Carlo simulations, and also when applied to actual macroeconomic series. The results indicate that our method is rather robust to model misspecification, although traditional multivariate methods also work well while univariate approaches are systematically outperformed. When interpolated series are subsequently used in econometric analyses, biases can emerge, but they are smaller with multivariate approaches, including factor-based ones.

Business Cycle Indexes

Business cycle indexes are used to get a timely and frequent description of the state of the economy and its likely development in the near future. This paper discusses two methods for constructing business cycle indexes, the traditional NBER method and a recently developed dynamic factor model, and compares these methods for the euro area. The results suggest that a reliable index can be constructed from a limited number of series that are selected using economic logic. We next decompose this index to identify variables that seem to be driving the euro area cycle.Business cycle indexes are used to get a timely and frequent description of the state of the economy and its likely development in the near future. This paper discusses two methods for constructing business cycle indexes, the traditional NBER method and a recently developed dynamic factor model, and compares these methods for the euro area. The results suggest that a reliable index can be constructed from a limited number of series that are selected using economic logic. We next decompose this index to identify variables that seem to be driving the euro area cycle. This analysis reveals important differences across countries in these driving variables.

Interpolation and Backdating with a Large Information Set

Existing methods for data interpolation or backdating are either univariate or based on a very limited number of series, due to data and computing constraints that were binding until the recent past. Nowadays large datasets are readily available, and models with hundreds of parameters are fastly estimated. We model these large datasets with a factor model, and develop an interpolation method that exploits the estimated factors as an efficient summary of all the available information. The method is compared with existing standard approaches from a theoretical point of view, by means of Monte Carlo simulations, and also when applied to actual macroeconomic series. The results indicate that our method is more robust to model misspecification, although traditional multivariate methods also work well while univariate approaches are systematically outperformed. When interpolated series are subsequently used in econometric analyses, biases can emerge, depending on the type of interpolation but again be reduced with multivariate approaches, including factor-based ones.

RECURRENCE OF MEMBRANOUS NEPHROPATHY AFTER RENAL TRANSPLANTATION INCIDENCE AND RISK FACTORS IN 1614 PATIENTS

The exact incidence of recurrence of membranous nephropathy (MN) after renal transplantation is not well documented because of the limited number of series involving a small number of patients. The aim of this study was to assess the incidence of MN recurrence in our population of renal transplant patients, to identify the risk factors associated with the recurrence, and to analyze the influence of the recurrence on graft and patient survival rates. The recurrence was defined as biopsy-proven MN on the renal graft in a patient whose original disease was MN. Among 1614 consecutive renal transplantations performed from January 1, 1980, to June 1, 1993, the incidence of recurrence was 26.3%, i.e., 5 recurrences out of 19 transplantations. We were unable to show pretransplant epidemiological, immunological, and therapeutic factors associated with recurrence. The HLA DR3 allele was present in 2 patients with recurrence (40%), compared with 3 patients without recurrence (21.4%). The early use of cyclosporine was not associated with a decreased prevalence of MN recurrence. Graft survival was not influenced by the recurrence. Three lymphomas were observed in the 19 transplanted patients with MN as causal nephropathy.

Odontogenic tumours. A series of 409 cases

Reports on the incidence of odontogenic tumours are infrequent with only a limited number of series having appeared in the literature. In this paper, the results of a multicentre retrospective study on the histologic types and relative frequencies of odontogenic tumours in Turkey are presented. The results indicated that the most frequent histologic type was ameloblastoma (36.5 per cent) and the area at greatest risk for the development of odontogenic tumours was the mandibular molar region. A Table showing the most likely type of tumour by location is also presented.