A Biopsy-Controlled Prospective Study of Contrast-Enhancing Diffuse Glioma Infiltration Based on FET-PET and FLAIR.

Accurately defining glioma infiltration is crucial for optimizing radiotherapy and surgery, but glioma infiltration is heterogeneous and MRI imperfectly defines the tumor extent. Currently, it is impossible to determine the tumor infiltration gradient within a FLAIR signal. O-(2-[18F]fluoroethyl)-L-tyrosine (FET)-PET often reveals high-grade glioma infiltration beyond contrast-enhancing areas on MRI. Here, we studied FET uptake dynamics in tumor and normal brain structures by dual-timepoint (10 min and 40-60 min post-injection) acquisition to optimize analysis protocols for defining glioma infiltration. Over 300 serial stereotactic biopsies from 23 patients (mean age 47, 12 female/11 male) of diffuse contrast-enhancing gliomas were taken from areas inside and outside contrast enhancement or outside the FET hotspot but inside FLAIR. The final diagnosis was G4 in 11, grade 3 in 10, and grade 2 in 2 patients. The target-to-background (TBRs) ratios and standardized uptake values (SUVs) were calculated in areas used for biopsy planning and in background structures. The optimal method and threshold values were determined to find a preferred strategy for defining glioma infiltration. Standard thresholding (1.6× uptake in the contralateral brain) in standard acquisition PET images differentiated a tumor of any grade from astrogliosis, although the uptake in astrogliosis and grade 2 glioma was similar. Analyzing an optimal strategy for infiltration volume definition astrogliosis could be accurately differentiated from tumor samples using a choroid plexus as a background. Early acquisition improved the AUC in many cases, especially within FLAIR, from 56% to 90% sensitivity and 41% to 61% specificity (standard TBR 1.6 vs. early TBR plexus). The current FET-PET evaluation protocols for contrast-enhancing gliomas are limited, especially at the tumor border where grade 2 tumor and astrogliosis have similar uptake, but using choroid plexus uptake in early acquisitions as a background, we can precisely define a tumor within FLAIR that was outside of the scope of current FET-PET protocols.

An optimal dose-fractionation for stereotactic body radiotherapy in peripherally, centrally and ultracentrally located early-stage non-small lung cancer.

Stereotactic body radiotherapy (SBRT), also known as stereotactic ablative radiotherapy (SABR), is commonly used in inoperable patients with early-stage non-small lung cancer (NSCLC). This treatment has good outcomes and low toxicity in peripherally located tumors. However, in lesions which are located close to structures such as the bronchial tree or mediastinum the risk of severe toxicity increases. This review summarizes the evidence of dose-fractionation in SBRT of NSCLC patients in various locations.

Combining amino acid PET and MRI imaging increases accuracy to define malignant areas in adult glioma.

Accurate determination of the extent and grade of adult-type diffuse gliomas is critical to patient management. In clinical practice, contrast-enhancing areas of diffuse gliomas in magnetic resonance imaging (MRI) sequences are usually used to target biopsy, surgery, and radiation therapy, but there can be discrepancies between these areas and the actual tumor extent. Here we show that adding 18F-fluoro-ethyl-tyrosine positron emission tomography (FET-PET) to MRI sequences accurately locates the most malignant areas of contrast-enhancing gliomas, potentially impacting subsequent management and outcomes. We present a prospective analysis of over 300 serial biopsy specimens from 23 patients with contrast-enhancing adult-type diffuse gliomas using a hybrid PET-MRI scanner to compare T2-weighted and contrast-enhancing MRI images with FET-PET. In all cases, we observe and confirm high FET uptake in early PET acquisitions (5-15 min after 18F-FET administration) outside areas of contrast enhancement on MRI, indicative of high-grade glioma. In 30% cases, inclusion of FET-positive sites changes the biopsy result to a higher tumor grade.

Glioma 2021 WHO Classification: The Superiority of NGS Over IHC in Routine Diagnostics.

INTRODUCTION: The accurate detection of genetic variants such as single substitutions (IDH1/2, TERT), chromosomal abnormalities (CDKN2A, 1p/19q deletions, and EGFR amplifications), or promoter methylations (MGMT) is critical for glioma patient management, as emphasized in the World Health Organization's (WHO's) most recent classification in 2021 (WHO CNS5). The purpose of this study was to evaluate novel innovative methods for determining IDH1/2 status in the context of WHO CNS5. METHODS: Multiple biomarkers were simultaneously screened using next-generation sequencing (NGS) on 34 glioma samples. In cases where the IDH1/2 status determined by immunohistochemistry (IHC) or multiplex ligation-dependent probe amplification (MLPA) was inconsistent with the NGS results, quantitative polymerase chain reaction (qPCR) and Sanger sequencing were performed to resolve the adjudicated discrepancy. RESULTS: IDH1/2 NGS results differ from IHC (7/13 samples) as well as MLPA reports (1/4 samples). All NGS findings were confirmed by qPCR and Sanger sequencing. WHO CNS5 requires assessment of multiple mutations for glioma classification. CONCLUSIONS: We demonstrated that qPCR or NGS performed in reference genetic laboratories, rather than IHC, is the most reliable method for IDH1/2 analysis. Clinicians should be aware of discrepancies in MLPA or IHC results and seek reconsultation in facilities with extensive access to advanced molecular technologies. Moreover, we proposed a new algorithm for the molecular diagnostic procedures in glioma patients based on the WHO CNS5.

Safety and Efficacy of Irradiation Boost Based on 18F-FET-PET in Patients with Newly Diagnosed Glioblastoma.

PURPOSE: Dual timepoint fluoro-ethyl-tyrosine (FET)-PET acquisition (10 and 60 minutes after FET injection) improves the definition of glioblastoma (GBM) location and shape. Here we evaluated the safety and efficacy of simultaneous integrated boost (SIB) planned using dual FET-PET for postoperative GBM treatment. PATIENTS AND METHODS: In this prospective pilot study (March 2017-December 2020), 17 patients qualified for FET-PET-based SIB intensity-modulated radiotherapy after resection. The prescribed dose was 78 and 60 Gy (2.6 and 2.0 Gy per fraction, respectively) for the FET-PET- and magnetic resonance (MR)-based target volumes. Eleven patients had FET-PET within 9 months to precisely define biological responses. Progression-free survival (PFS), overall survival (OS), toxicities, and radiation necrosis were evaluated. Six patients (35%) had tumors with MGMT promoter methylation. RESULTS: The 1- and 2-year OS and PFS rates were 73% and 43% and 53% and 13%, respectively. The median OS and PFS were 24 [95% confidence interval (CI), 9-26] and 12 (95% CI, 6-18) months, respectively. Two patients developed uncontrolled seizures during radiotherapy and could not receive treatment per protocol. In patients treated per protocol, 7 of 15 presented with new or increased neurologic deficits in the first month after irradiation. Radiation necrosis was diagnosed by MRI 3 months after SIB in 5 patients and later in another 2 patients. In 2 patients, the tumor was larger in FET-PET images after 6 months. CONCLUSIONS: Survival outcomes using our novel dose-escalation concept (total 78 Gy) were promising, even within the MGMT unmethylated subgroup. Excessive neurotoxicity was not observed, but radionecrosis was common and must be considered in future trials.

Polish Multi-Institutional Study of Children with Ependymoma-Clinical Practice Outcomes in the Light of Prospective Trials.

We performed a multi-institutional analysis of 74 children with ependymoma to evaluate to what extent the clinical outcome of prospective trials could be reproduced in routine practice. The evaluation of factors that correlated with outcome was performed with a log rank test and a Cox proportional-hazard model. Survival was estimated with the Kaplan-Meier method. The majority of patients had brain tumours (89%). All had surgery as primary treatment, with adjuvant radiotherapy (RTH) and chemotherapy (CTH) applied in 78% and 57%, respectively. Median follow-up was 80 months and 18 patients died. Five- and 10-year overall survival (OS) was 83% and 73%. Progression was observed in 32 patients, with local recurrence in 28 cases. The presence of metastases was a negative prognostic factor for OS. Five- and 10-year progression-free survival (PFS) was 55% and 40%, respectively. The best outcome in patients with non-disseminated brain tumours was observed when surgery was followed by RTH (+/-CTH afterwards; p = 0.0001). Children under 3 years old who received RTH in primary therapy had better PFS (p = 0.010). The best outcome of children with ependymoma is observed in patients who received radical surgery followed by RTH, and irradiation should not be omitted in younger patients. The role of CTH remains debatable.

Glioma Biopsy Based on Hybrid Dual Time-Point FET-PET/MRI-A Proof of Concept Study.

Neuroimaging based on O-[2-(18F)fluoroethyl]-l-tyrosine (FET)-PET provides additional information on tumor grade and extent compared with MRI. Dynamic PET for biopsy target selection further improves results but is often clinically impractical. Static FET-PET performed at two time-points may be a good compromise, but data on this approach are limited. The aim of this study was to compare the histology of lesions obtained from two challenging glioma patients with targets selected based on hybrid dual time-point FET-PET/MRI. Five neuronavigated tumor biopsies were performed in two difficult cases of suspected glioma. Lesions with (T1-CE) and without contrast enhancement (T1 and T2-FLAIR) on MRI were selected. Dual time-point FET-PET imaging was performed 5-15 min (PET10) and 45-60 min (PET60) after radionuclide injection. The most informative FET-PET/MRI images were coregistered with MRI in time of biopsy planning. Five biopsy targets (three from high uptake and two from moderate uptake FET areas) thought to represent the most malignant sites and tumor extent were selected. Histopathological findings were compared with FET-PET and MRI images. Increased FET uptake in the area of non-CE locations on MRI correlated well with high-grade gliomas localized as far as 3 cm from T1-CE foci. Selecting a target in the motor cortex based on FET kinetics defined by dual time-point PET resulted in a grade IV diagnosis after previous negative biopsies based on MRI. An additional grade III diagnosis was obtained from an area of glioma infiltration with moderate FET uptake (between 1 and 1.25 SUV). These findings seem to show that dual time-point FET-PET-based biopsies can provide additional and clinically useful information for glioma diagnosis. Selection of targets based on dual time-point images may be useful for determining the most malignant tumor areas and may therefore be useful for resection and radiotherapy planning.

High-Grade Gliomas in Children-A Multi-Institutional Polish Study.

Due to the rarity of high-grade gliomas (HGG) in children, data on this topic are scarce. The study aimed to investigate the long-term results of treatment of children with HGG and to identify factors related to better survival. We performed a retrospective analysis of patients treated for HGG who had the main tumor located outside the brainstem. The evaluation of factors that correlated with better survival was performed with the Cox proportional-hazard model. Survival was estimated with the Kaplan-Meier method. The study group consisted of 82 consecutive patients. All of them underwent surgery as primary treatment. Chemotherapy was applied in 93% of children with one third treated with temozolomide. After or during the systemic treatment, 79% of them received radiotherapy with a median dose of 54 Gy. Median follow-up was 122 months, and during that time, 59 patients died. One-, 2-, 5-, and 10-year overall survival was 78%, 48%, 30% and 17%, respectively. Patients with radical (R0) resection and temozolomide-based chemotherapy had better overall survival. Progression-free survival was better in patients after R0 resection and radical radiotherapy. The best outcome in HGG patients was observed in patients after R0 resection with immediate postoperative temozolomide-based chemotherapy and radical radiotherapy.

Stereotactic Radiosurgery of Brain Metastasis in Patients with a Poor Prognosis: Effective or Overtreatment?

PURPOSE: Stereotactic radiosurgery (SRS) of brain metastasis in patients with a poor prognosis remains controversial. Here, we compared results of SRS alone to whole brain radiotherapy (WBRT) in poor-prognosis patients and defined the most important unfavorable prognostic factors related to early death after SRS alone. PATIENTS AND METHODS: In this retrospective analysis of prospective SRS data, 180 patients with brain metastases not previously treated with WBRT were analyzed. Results of SRS were compared to WBRT by propensity score matching in patients with a poor prognosis defined by graded prognostic assessment (GPA) <2. Further, SRS patients were divided into training (n=82) and validation (n=48) cohorts. Overall survival (OS) and the risk of early death were defined by univariable and multivariable analyses. RESULTS: Median survival of the WBRT and SRS cohorts was 86 days (IQR: 38-172 days) and 201 days (IQR: 86-not reached), respectively (p<0.0001). OS in patients with GPA<2 was significantly longer in the SRS vs WBRT group (123 vs 58 days; p=0.008). Survival was longer in the SRS group in a propensity score matched analysis. In multivariable analysis, GPA (OR: 0.44, 95%CI: 0.21-0.95; p=0.001), extensive extracranial disease (OR: 0.13, 95%CI: 0.02-0.66; p=0.013), and serious neurological deficits (OR: 0.13, 95%CI: 0.04-0.45; p=0.001) were associated with early death. If one factor was favorable, 73% (training) and 92% (validation) of patients survived three months. Patients with GPA <2 presenting with serious neurological deficits and extensive extracranial disease had a low expected benefit due to the highest risk of death within three months (AUC: 0.822 training; 0.932 validation). CONCLUSION: SRS is a viable treatment option for patients with a poor prognosis defined as GPA <2. Good neurological status, extracranial oligometastatic disease, or GPA ≥2 should be present to justify SRS in patients with brain metastases.

A Cost-Effectiveness and Quality of Life Analysis of Different Approaches to the Management and Treatment of Localized Prostate Cancer.

The aim of this study was to compare the cost-effectiveness and quality-adjusted life years (QALYs) of active monitoring (AM), radical prostatectomy (PR), and external-beam radiotherapy with neoadjuvant hormone therapy (RT) for localized prostate cancer. Microsimulations of radical prostatectomy, 3D-conformal radiotherapy, or active monitoring were performed using Medicare reimbursement schedules and clinical trial results for a target population of men aged 50-69 years with newly diagnosed localized prostate cancer (T1-T2, NX, M0) over a time horizon of 10 years. Quality-adjusted life years (QALYs) and costs were assessed and sensitivity analyses performed. Monte Carlo simulations revealed that the mean cost for AM, PR, and RT were $15,654, $18,791, and $30,378, respectively, and QALYs were 6.96, 7.44, and 7.9 years, respectively. The incremental cost-effectiveness ratio (ICER) was $6,548 for PR over AM and $68,339 for RT over PR. Results were sensitive to the number of years of follow-up and procedure cost. With relaxed assumptions for AM, the ICER of PR and RT met the societal willingness to pay (WTP) threshold of $50,000 per QALY. Compared with AM, PR was highly cost-effective. RT and PR for localized prostate cancer can be cost-effective, but RT must offer increased QALYs or decreased procedural costs to be cost-effective compared to PR. Newer and cheaper radiotherapy strategies like stereotactic body radiotherapy may play a crucial role in future early prostate cancer management.

Biomarker concordance between molecular stereotactic biopsy and open surgical specimens in gliomas.

AIMS: To compare 1p/19q codeletion, MGMT promoter methylation, and IDH mutation status in stereotactic biopsy and open craniotomy specimens. CLINICAL RATIONALE: The latest WHO classification of gliomas requires assessment of the expression of molecular markers. Samples can be obtained for molecular assays via open craniotomy or molecular stereotactic biopsy (MSB). However, there is uncertainty as to whether MSB is representative of the entire tumour, and therefore how reliable it is for treatment planning. PATIENTS AND METHODS: We examined 11 patients diagnosed with brain tumours suspicious of glioma who underwent open craniotomy after stereotactic biopsy and in whom multiple biomarkers were assessed in both sets of samples by methylation-specific multiplex ligation-dependent probe amplification. Institutional Review Board ethical approval was granted (KB 694/2018). RESULTS: The initial histopathological grade as determined by stereotactic biopsy was the same as in the samples obtained by open surgery. Further, the marker profile used here was valid in both high- and low-grade gliomas. CONCLUSION AND CLINICAL IMPLICATION: MSB is a reliable way to obtain material for precision medicine approaches.

The impact of adjuvant radiotherapy on molecular prognostic markers in gliomas.

PURPOSE: Changes in MGMT promoter methylation, IDH1 and IDH2 mutation, and 1p/19q co-deletion status in gliomas between first and subsequent resections and their associated clinical factors are poorly described. In this study, we assayed these biomarkers in the clinical setting. PATIENTS AND METHODS: We used multiplex ligation-dependent probe amplification to measure MGMT promoter methylation, IDH mutation status, and 1p/19q co-deletion in 45 paired tumor samples from patients undergoing resection and subsequent re-resections for gliomas. RESULTS: Molecular changes were present in 20 patients (44%). At least one molecular characteristic changed over time in 89% of patients with primary grade III tumors. Gliomas with IDH wild-type and/or non-co-deleted were stable, but IDH1/2 mutation and/or co-deletion were sometimes lost at the time of recurrence. In a multivariate analysis, adjuvant radiotherapy alone was independently associated (P=0.02) with changes in molecular profile. CONCLUSION: Molecular biomarkers change in gliomas during the course of the disease, most often MGMT methylation status. These changes in genetic profiles are related to adjuvant treatment with radiotherapy alone, which might be important for individualized treatment planning over the disease course.

Prognostic value of subventricular zone involvement in relation to tumor volumes defined by fused MRI and O-(2-[18F]fluoroethyl)-L-tyrosine (FET) PET imaging in glioblastoma multiforme.

BACKGROUND: Subventricular zone (SVZ) involvement is associated with a dismal prognosis in patients with glioblastoma multiforme (GBM). Dual-time point (dtp) O-(2-[18F]fluoroethyl)-L-tyrosine (FET) PET/CT (PET) may be a time- and cost-effective alternative to dynamic FET PET, but its prognostic value, particularly with respect to SVZ involvement, is unknown. METHODS: Thirty-five patients had two scans 5-15 and 50-60 min after i.v. FET injection to define tumor volumes and SVZ involvement before starting radiotherapy. Associations between clinical progression markers, MRI- and dtp FET PET-based tumor volumes, or SVZ involvement and progression-free (PFS) and overall survival (OS) were assessed in univariable and multivariable analyses. RESULTS: The extent of resection was not related to outcomes. Albeit non-significant, dtp FET PET detected more SVZ infiltration than MRI (60% vs. 51%, p = 0.25) and was significantly associated with poor survival (p < 0.03), but PET-T1-Gad volumes were larger in this group (p < 0.002). Survival was shorter in patients with larger MRI tumor volumes, larger PET tumor volumes, and worse Karnofsky performance status (KPS), with fused PET-T1-Gad and KPS significant in multivariable analysis (p < 0.03). Uptake kinetics was not associated with treatment outcomes. CONCLUSIONS: FET PET-based tumor volumes may be useful for predicting worse prognosis glioblastoma. Although the presence of SVZ infiltration is linked to higher PET/MRI-based tumor volumes, the independent value of dtp FET PET parameters and SVZ infiltration as prognostic markers pre-irradiation has not been confirmed.

Large In-mask Motion during Frameless Radiosurgery of a Brain Metastasis.

Frameless radiosurgery is now a common alternative to traditional in-frame treatment. Several dosimetric studies have reported small in-mask positioning inaccuracies during frameless radiosurgery. We present a case of an uncommonly large deviation in in-mask motion detected offline in a patient undergoing linear accelerator-based frameless radiosurgery. Our case illustrates how the use of a thermoplastic mask can lead to unacceptable setup errors for passive image-guided radiosurgery. The case underlines the need for correct patient preparation, adequate time between mask molding and computed tomography, and routine intrafraction imaging. Image-guided positioning is recommended to achieve clinically acceptable setup accuracy (< 1 mm) for stereotactic radiosurgery.

Evaluation of Brain Edema Formation Defined By MRI After LINAC-based Stereotactic Radiosurgery.

BACKGROUND: Peri-lesional edema is a serious and well-known complication of stereotactic radiosurgery (SRS). Here we evaluated edema risk after SRS and assessed its formation and resolution dynamics. PATIENTS AND METHODS: 107 patients underwent SRS for heterogeneous diagnoses: 34 (29%) with arteriovenous malformations, 38 (35%) with meningiomas, 16 (15%) with metastatic tumors, 16 (15%) with acoustic neuromas, 3 with (3%) cavernomas, and 2 (2%) each with anaplastic astrocytomas and anaplastic oligoastrocytomas. Edema area was delineated in MRI T2-FLAIR sequences 0, 6, 12, 18, 24, 30, and 38 months after treatment. Lesion location was defined as either above (n = 80) or below (n = 32) the "Frankfurt modified line" (FML). RESULTS: 17% of patients developed or had worsening post-treatment edema. Edema volume was maximal at 6 months (mean 7.2, SD 1.2) post radiosurgery. Post-SRS edema was 5.1 (1.06 - 24.53) times more likely in patients with lesions above the FML. There was no association between edema development and age, PTV size, number of beams, and diagnosis (p = 0.07). CONCLUSIONS: Radiosurgery-associated edema develops within 6 months of treatment and decreases over time. Edema occurrence is strongly related to lesion location, and its presence is much more likely when the treated lesions are situated above the Frankfurt line.

Relationship between Glioblastoma Dose Volume Parameters Measured by Dual Time Point Fluoroethylthyrosine-PET and Clinical Outcomes.

Glioblastoma multiforme (GBM) is highly invasive. Despite irradiation with wide margins, GBM usually recurs in-field. Recent in vitro data have suggested that progression might be promoted by sublethal irradiation. Fluoroethylthyrosine-PET (FET-PET) can be used to detect glioblastoma invasion not apparent on MRI. We therefore performed a retrospective analysis of a prospective clinical study to examine whether glioblastoma outcomes depend on dose volume parameters measured by MRI and FET-PET. Twenty-three patients were prospectively recruited to a study examining the role of dual time point FET-PET in the treatment planning of GBM radiotherapy. The dose delivered to the site of recurrence was subdivided into suboptimal-dose (SOD) and high-dose (HD) areas. Types of progression were defined for correlation with dosimetric parameters including V100% of gross tumor volume (GTV)PET, GTVPETMRI, and GTVMRI. The HD area did not cover the entire GTVPETMRI in any case. Recurrences were significantly more frequent in the SubD area (chi-squared test, p = 0.004). There was no relationship between increasing dose volume and progression. The V100% for GTVPET and progression-free survival (PFS) was positively correlated (Spearman's rho 0.417; p = 0.038). Progression is more common in areas with suboptimal dosing. Dose heterogeneity within GTVPET may be responsible for shorter PFS.

Pre-irradiation tumour volumes defined by MRI and dual time-point FET-PET for the prediction of glioblastoma multiforme recurrence: A prospective study.

BACKGROUND AND PURPOSE: The diagnostic accuracy of magnetic resonance imaging (MRI) for glioblastoma multiforme (GBM) is suboptimal. We analysed pre-treatment MRI- and dual time-point 18F-fluoroethylthyrosine-PET (FET-PET)-based target volumes and GBM recurrence patterns following radiotherapy with temozolomide. MATERIALS AND METHODS: Thirty-four patients with primary GBM were treated according to MRI-based treatment volumes (GTVRM). Patients underwent dual time-point FET-PET scans prior to treatment, and biological tumour volumes (GTVPET) were contoured but not used for target definition. Progressions were classified based on location of primary GTVs. Volume and uniformity of MRI- vs. FET-PET/CT-derived GTVs and progression patterns assessed by MRI were analysed. RESULTS: FET-based GTVs measured 10min after radionuclide injection (a.r.i.; median 37.3cm(3)) were larger than GTVs measured 60min a.r.i. (median 27.7cm(3)). GTVPET volumes were significantly larger than corresponding MRI-based GTVs. MRI and PET concordance for the identification of glioblastoma GTVs was poor (mean uniformity index 0.4). 74% of failures were inside primary GTVPET volumes, with no solitary progressions inside the MRI-defined margin +20mm but outside the GTVPET detected. CONCLUSIONS: The size and geometry of GTVs differed in the majority of patients. The GTVPET volume depends on time after radionuclide injection. FET-PET better defined failure site than MRI alone.

Whole breast irradiation vs. APBI using multicatheter brachytherapy in early breast cancer - simulation of treatment costs based on phase 3 trial data.

PURPOSE: A recent large phase 3 trial demonstrated that the efficacy of accelerated partial-breast irradiation (APBI) in the treatment of early breast cancer is non-inferior to that of whole breast irradiation (WBI) commonly used in this indication. The aim of this study was to compare the costs of treatment with APBI and WBI in a population of patients after conserving surgery for early breast cancer, and to verify if the use of APBI can result in direct savings of a public payer. MATERIAL AND METHODS: The hereby presented cost analysis was based on the results of GEC-ESTRO trial. Expenditures for identified cost centers were estimated on the basis of reimbursement data for the public payer. After determining the average cost of early breast cancer treatment with APBI and WBI over a 5-year period, the variance in this parameter resulting from fluctuations in the price per single procedure was examined on univariate sensitivity analysis. Then, incremental cost-effectiveness ratio (ICER) was calculated to verify the cost against clinical outcome. Finally, a simulation of public payer's expenditures for the treatment of early breast cancer with APBI and WBI in 2013 and 2025 has been conducted. RESULTS: The average cost of treatment with APBI is lower than for WBI, even assuming a potential increase in the unit price of the former procedure. There was no additional health benefit of WBI and the calculation of cost-effectiveness was based on the absolute difference in overall local control rate. However, this difference (0.92% vs. 1.44%) was fairly minimal and was not identified as statistically significant during 5 years. CONCLUSIONS: The use of APBI as an alternative to WBI in the treatment of early breast cancer would substantially reduce healthcare expenditures in both 2013 and 2025, even assuming an increase in the price per single APBI procedure.

The Sum of Tumour-to-Brain Ratios Improves the Accuracy of Diagnosing Gliomas Using 18F-FET PET.

Gliomas are common brain tumours, but obtaining tissue for definitive diagnosis can be difficult. There is, therefore, interest in the use of non-invasive methods to diagnose and grade the disease. Although positron emission tomography (PET) with 18F-fluorethyltyrosine (18F-FET) can be used to differentiate between low-grade (LGG) and high-grade (HGG) gliomas, the optimal parameters to measure and their cut-points have yet to be established. We therefore assessed the value of single and dual time-point acquisition of 18F-FET PET parameters to differentiate between primary LGGs (n = 22) and HGGs (n = 24). PET examination was considered positive for glioma if the metabolic activity was 1.6-times higher than that of background (contralateral) brain, and maximum tissue-brain ratios (TBRmax) were calculated 10 and 60 min after isotope administration with their sums and differences calculated from individual time-point values. Using a threshold-based method, the overall sensitivity of PET was 97%. Several analysed parameters were significantly different between LGGs and HGGs. However, in a receiver operating characteristics analysis, TBR sum had the best diagnostic accuracy of 87% and sensitivity, specificity, and positive and negative predictive values of 100%, 72.7%, 80%, and 100%, respectively. 18F-FET PET is valuable for the non-invasive determination of glioma grade, especially when dual time-point metrics are used. TBR sum shows the greatest accuracy, sensitivity, and negative predictive value for tumour grade differentiation and is a simple method to implement. However, the cut-off may differ between institutions and calibration strategies would be useful.

Preliminary results of linac-based radiosurgery in arteriovenous malformations and cerebral tumours in the Oncology Centre in Bydgoszcz.

AIM OF THE STUDY: Efficacy of stereotactic radiosurgery (SRS) in the treatment in cerebral AVM's, mennigiomas, metastases, acoustic neuromas and recurrent anaplastic gliomas is well documented. The object of this work was the analysis of the results of the treatment of AVM and selected cerebral lesions with linear accelerator-based stereotactic radiosurgery. MATERIAL AND METHODS: THE LESIONS INCLUDED: 12 AVMs, 2 cavernomas, 27 meningiomas, 16 metastases, 5 acoustic neuromas, 16 gliomas in 78 patients. A mean radiation dose of 16Gy was delivered to the tumour or AVM margin and 12Gy to the tumours located in a ponto-cerebellar angle. Follow-up was 18 months. RESULTS: Control of tumour growth or AVM was achieved in all cases after 6 months and radiological regression was observed in 20 cases after 12 months. The best results were noted in AVM's, meningiomas and neuromas.There were no new permanent deficits nor complications after radiosurgery requiring medicamentation. CONCLUSIONS: Organization of SRS in Oncological Center in Bydgoszcz involving close co-operation of radiotherapist, neurosurgeon and physicist in the process of qualification and treatment planning is based on the best global standards. Preliminary results of treatment are consistent with the literature data. A longer follow-up is required to determine the long term efficacy and the toxicity of this treatment in our institution.