SAFESTEREO: phase II randomized trial to compare stereotactic radiosurgery with fractionated stereotactic radiosurgery for brain metastases

BACKGROUND

Stereotactic radiosurgery (SRS) is a frequently chosen treatment for patients with brain metastases and the number of long-term survivors is increasing. Brain necrosis (e.g. radionecrosis) is the most important long-term side effect of the treatment. Retrospective studies show a lower risk of radionecrosis and local tumor recurrence after fractionated stereotactic radiosurgery (fSRS, e.g. five fractions) compared with stereotactic radiosurgery in one or three fractions. This is especially true for patients with large brain metastases. As such, the 2022 ASTRO guideline of radiotherapy for brain metastases recommends more research to fSRS to reduce the risk of radionecrosis. This multicenter prospective randomized study aims to determine whether the incidence of adverse local events (either local failure or radionecrosis) can be reduced using fSRS versus SRS in one or three fractions in patients with brain metastases.

METHODS

Patients are eligible with one or more brain metastases from a solid primary tumor, age of 18 years or older, and a Karnofsky Performance Status ≥ 70. Exclusion criteria include patients with small cell lung cancer, germinoma or lymphoma, leptomeningeal metastases, a contraindication for MRI, prior inclusion in this study, prior surgery for brain metastases, prior radiotherapy for the same brain metastases (in-field re-irradiation). Participants will be randomized between SRS with a dose of 15-24 Gy in 1 or 3 fractions (standard arm) or fSRS 35 Gy in five fractions (experimental arm). The primary endpoint is the incidence of a local adverse event (local tumor failure or radionecrosis identified on MRI scans) at two years after treatment. Secondary endpoints are salvage treatment and the use of corticosteroids, bevacizumab, or antiepileptic drugs, survival, distant brain recurrences, toxicity, and quality of life.

DISCUSSION

Currently, limiting the risk of adverse events such as radionecrosis is a major challenge in the treatment of brain metastases. fSRS potentially reduces this risk of radionecrosis and local tumor failure.

TRIAL REGISTRATION

ClincalTrials.gov, trial registration number: NCT05346367 , trial registration date: 26 April 2022.

Rezidivraten und Form des Rezidivs nach endoluminaler Ablation der Vena saphena magna – Ein Vergleich von Laserablation (EVLA) 1470 nm, Radiofrequenz (RFITT und ClosureFast) sowie Heißdampf mit einer durchschnittlichen Nachbeobachtungszeit von 3,8 Jahren

Einleitung Erkrankungen des Venensystems, insbesondere auch die Insuffizienz der Vena saphena magna (VSM), gehören zu den häufigsten Krankheitsbildern in unserer Gesellschaft. Zur Behandlung stehen neben Krossektomie und Stripping sowie reiner Sklerosierungstherapie verschiedene endovenöse thermische Verfahren zur Verfügung, die in der vorliegenden Studie untereinander verglichen werden sollten.

Methoden Zwischen 2009 und 2013 wurde bei insgesamt 297 Patienten die insuffiziente VSM mit einer der 4 Methoden EVLA 1470 nm, ClosureFast, RFITT oder Heißdampf abladiert. Als primärer Endpunkt wurde die Rezidiv-Häufigkeit definiert. Die Nachkontrollen mit Duplexsonografie fanden 14 Tage postoperativ, 3 Monate postoperativ, nach 1 Jahr und schließlich jährlich mit einer durchschnittlichen Nachbeobachtungszeit von 3,8 Jahren und einer Follow-up-Rate von 81 % statt.

Ergebnisse Zum Zeitpunkt der letzten Nachkontrolle zeigten sich folgende anatomische Erfolgsraten der behandelten VSM: ClosureFast 95 %, EVLA 97 %, RFITT 79 % und Heißdampf 71 %. Schwerwiegende Komplikationen traten nur beim Heißdampf auf (Nekrosen an der Punktionsstelle), die Schmerzintensität lag bei allen Methoden 14 Tage postoperativ bei einem Median von 1–3 auf einer Skala von 1–10, bei den nachfolgenden Kontrollen lag der Median bei allen Methoden bei 1. Sowohl der Global Index Score (CIVIQ-Score) als auch der Venous Clinical Severity Score (VCSS) ließen sich durch alle endovenösen thermischen Methoden signifikant verbessern. In 5–12 % der Fälle trat ein Reflux der zuvor suffizienten Vena saphena magna accessoria (VSAA) auf.

Diskussion EVLA und ClosureFast sind zur Behandlung von Insuffizienzen der VSM mit hoher Erfolgsrate und vergleichbaren Ergebnissen zu Krossektomie und Stripping geeignet. Die Verfahren RFITT und Heißdampf zeigen im Vergleich signifikant niedrigere Verschlussraten und sind damit besonderen Situationen vorbehalten. Besonderes Augenmerk sollte auf das Vorhandensein einer zunächst nicht refluxiven VSAA gerichtet werden. Da sich hier eine erhöhte Rezidivrate bei dieser Vene zeigte, erscheint es sinnvoll, die VSAA primär mit zu abladieren.

Wicksell's Problem in Local Stereology

Wicksell's classical corpuscle problem deals with the retrieval of the size distribution of spherical particles from planar sections. We discuss the problem in a local stereology framework. Each particle is assumed to contain a reference point and the individual particle is sampled with an isotropic random plane through this reference point. Both the size of the section profile and the position of the reference point inside the profile are recorded and used to recover the distribution of the corresponding particle parameters. Theoretical results concerning the relationship between the profile and particle parameters are discussed. We also discuss the unfolding of the arising integral equations, uniqueness issues, and the domain of attraction relations. We illustrate the approach by providing reconstructions from simulated data using numerical unfolding algorithms.

Estimating the surface area of nonconvex particles from central planar sections

In this paper, we present a new surface area estimator in local stereology. This new estimator is called the 'Morse-type surface area estimator' and is obtained using a two-stage sampling procedure. First a plane section through a fixed reference point of a three-dimensional structure is taken. In this section plane, a modification of the area tangent count method is used. The Morse-type estimator generalizes Cruz-Orive's pivotal estimator for convex objects to nonconvex objects. The advantages of the Morse-type estimator over existing local surface area estimators are illustrated in a simulation study. The Morse-type estimator is well suited for computer-assisted confocal microscopy and we demonstrate its practicability in a biological application: the surface area estimation of the nuclei of giant-cell glioblastoma from microscopy images. We also present an interactive software that allows the user to efficiently obtain the estimator.

Diabetes in relation to breast cancer relapse and all-cause mortality in elderly breast cancer patients: a FOCUS study analysis

BACKGROUND

In developed countries, 40% of breast cancer patients are >65 years of age at diagnosis, of whom 16% additionally suffer from diabetes. The aim of this study was to assess the impact of diabetes on relapse-free period (RFP) and overall mortality in elderly breast cancer patients.

PATIENTS AND METHODS

Patients were selected from the retrospective FOCUS cohort, which contains detailed information of elderly breast cancer patients. RFP was calculated using Fine and Gray competing risk regression models for patients with diabetes versus patients without diabetes. Overall survival was calculated by Cox regression models, in which patients were divided into four groups: no comorbidity, diabetes only, diabetes and other comorbidity or other comorbidity without diabetes.

RESULTS

Overall, 3124 patients with non-metastasized breast cancer were included. RFP was better for patients with diabetes compared with patients without diabetes (multivariable HR 0.77, 95% CI 0.59-1.01), irrespective of other comorbidity and most evident in patients aged ≥75 years (HR 0.67, 95% CI 0.45-0.98). The overall survival was similar for patients with diabetes only compared with patients without comorbidity (HR 0.86, 95% CI 0.45-0.98), while patients with diabetes and additional comorbidity had the worst overall survival (HR 1.70, 95% CI 1.44-2.01).

CONCLUSION

When taking competing mortality into account, RFP was better in elderly breast cancer patients with diabetes compared with patients without diabetes. Moreover, patients with diabetes without other comorbidity had a similar overall survival as patients without any comorbidity. Possibly, unfavourable effects of (complications of) diabetes on overall survival are counterbalanced by beneficial effects of metformin on the occurrence of breast cancer recurrences.

Algorithms to estimate the rose of directions of a spatial fibre system

Summary The directional measure (which is up to normalization the rose of directions) is used to quantify anisotropy of stationary fibre processes in three-dimensional space. There exist a large number of approaches to estimate this measure from the rose of intersections (which is the mean number of intersections of fibres with lower dimensional test sets). Three recently suggested nonparametric algorithms to solve this problem are reviewed and compared. They were obtained from solutions of a least squares problem, a more general convex optimization problem and a linear program, respectively. Application to two different carbon fibre architectures and to simulated data allow an empirical comparison of these approaches. In addition, estimators for the associated zonoid (or Steiner compact) are suggested. This set turns out to be an intuitive tool for visualization.

Directional analysis of digitized three-dimensional images by configuration counts

A method for estimating the orientated rose of normal directions of a three-dimensional (3D) set Z from a digitization of Z, i.e. a voxel image, is presented. It is based on counts of informative configurations in n x n x n voxel cubes. An algorithm for finding all informative configurations is proposed and an estimation procedure is described in detail for the case n= 2. The presented method is a 3D version of a method of estimating the orientated rose of binary planar images using n x n configurations. A new feature is the design-based approach, being more appropriate for biomedical image analysis than the formerly applied model-based approach.

Directional analysis of digitized planar sets by configuration counts

The oriented rose of normal directions of a random set Z can be used to quantify its anisotropy. A method for estimating this quantity from a digitization of Z in a sampling window, i.e. its pixel image, is presented. The image is analysed locally by considering pixel squares of size n x n. This allows us to count the number of different types of n x n configurations in the pixel image. We show that it suffices to restrict attention to the so-called informative configurations. The number of informative configurations increases only polynomially in n. An algorithm to find these informative configurations is presented. Furthermore, estimators of the oriented rose based on counts of observed informative configurations are derived. The procedure is illustrated by a simulated example and an analysis of a microscopic image of steel.