Homogenous mixing and network approximations in discrete-time formulation of a SIRS model.

A discrete-time deterministic epidemic model is proposed to better understand the contagious dynamics and the behaviour observed in the incidence of real infectious diseases. For this purpose, we analyse a SIRS model both in a random-mixing approach and in a small-world network formulation. The models include the basic parameters that characterize an epidemic: infection and recovery times, as well as mechanisms of contagion. Depending on the parameters, the random-mixing model has different types of behaviour of an epidemic: pathogen extinction; endemic infection; sustained oscillations and dynamic extinction. Spatial effects are included in our network-based approach, where each individual of a population is represented by a node of a small-world network. Our network-based approach includes rewiring connections to account for time-varying network structure, a consequence of the natural response to the emergence of an epidemic (e.g. avoiding contacts with infected individuals). Random and adaptive rewiring conditions are analysed and numerical simulation are made. A comparison of model predictions with the actual effects of COVID-19 infection on population that occurred in Italy and France is produced. Results of the time series of infected people show that our adaptive evolving networks represent effective strategies able to decrease the epidemic spreading.

Volumetric Modulated Arc Therapy After Lung Sparing Surgery for Malignant Pleural Mesothelioma: A Single Institution Experience.

INTRODUCTION: We investigated the possible role of volumetric modulated arc therapy (VMAT) in the setting of adjuvant treatment of malignant pleural mesothelioma (MPM) after lung-sparing surgery with pleurectomy and decortication. MATERIALS AND METHODS: Patients affected by MPM who had undergone pleurectomy and decortication and adjuvant radiotherapy with VMAT were included. The endpoints of the present analysis were local control, progression-free survival, and overall survival. Assessment of the variables affecting survival was performed using univariate and multivariate Cox proportional hazard models. RESULTS: A total of 49 patients were included in the present study. Of the 49 patients, 96% had been treated with a trimodality approach. Radiotherapy was delivered to a median dose of 44 Gy in 22 fractions (range, 22-59.4 Gy). The treatment was well tolerated, with just 2 grade 3 acute toxicities, 1 grade 5, and 2 grade 4 toxicities recorded during the follow-up period. The median follow-up period was 27.4 months. The local control rate at 12, 24, and 36 months was 75.2%, 67.4%, and 56.5%, respectively. The median progression-free survival was 14.9 months (95% confidence interval [CI], 7.5-25.2). The median overall survival was 21.5 months (95% CI, 15.3-37.1). On multivariate analysis, the administration of carboplatin- instead of cisplatin-based chemotherapy (hazard ratio, 2.97; 95% CI, 1.22-7.26; P = .017) and R2 resection (hazard ratio, 1.95; 95% CI, 1.27-2.99; P = .002) showed a negative correlation with overall survival. On univariate analysis, the percentage of the heart receiving >20 Gy and >30 was associated with the occurrence of late pneumonitis (P = .018 and P = .077). CONCLUSION: VMAT is feasible in the setting of MPM after lung-sparing surgery. The toxicity rates were reduced with this technique compared with historical data of older techniques. Local and distant failure remain a major issue to be addressed in future trials.

Surgery Followed by Hypofractionated Radiosurgery on the Tumor Bed in Oligometastatic Patients With Large Brain Metastases. Results of a Phase 2 Study.

PURPOSE: This prospective phase II study assessed safety and feasibility of surgery followed by hypofractionated radiosurgery (HSRS) on the tumor bed in oligometastatic patients with single large brain metastases (BMs). METHODS AND MATERIALS: Between June 2015 and May 2018, 101 patients were enrolled. Oligometastatic disease was defined by a maximum of 5 extracranial metastatic lesions. HSRS was performed within 1 month of surgery and consisted of 30 Gy in 3 fractions. Local control, occurrence of new BMs, overall survival, and treatment-related toxicities were assessed. RESULTS: At a median follow-up time of 26 months, local recurrence occurred in 6 patients (5.9%). Six-month, 1-year, and 2-year local control rates were 100%, 98.9% ± 1.1%, and 85.9% ± 0.6%, respectively. New BMs occurred in 39 patients (38.6%); median brain distant progression time and 6-month, 1-year, and 2-year brain distant progression rates were 39 months (95% CI, 19-39 months), 17% ± 3.7%, 31.4% ± 4.8%, and 42.5% ± 5.9%, respectively. At the last observation time, 50 patients (49.5%) were alive and 51 (50.5%) were dead; 10 patients died owing to neurologic causes and 40 as a result of systemic progression. Median overall survival time and 6-month, 1-year, and 2-year overall survival rates were 22 months (95% CI, 20-30 months), 95% ± 2.1%, 81.9% ± 3.8%, and 46.6% ± 6%, respectively. Infratentorial site, residual tumor volume, longer interval time between primary diagnosis and occurrence of BMs, and oligometastatic disease status significantly influenced outcome. Grade 2 to 3 radionecrosis occurred in 26 patients. Neurocognitive functions remained stable or, in some cases, improved. CONCLUSIONS: Surgery followed by HSRS on the tumor bed is a safe and effective approach, affording good brain control with acceptable toxicities. As for extracranial metastatic sites, patients with BMs can benefit from local ablative treatment in the context of an oligometastatic disease.

Role of multidimensional assessment of frailty in predicting outcomes in older patients with glioblastoma treated with adjuvant concurrent chemo-radiation.

BACKGROUND: Our aim was to evaluate the impact of comorbidities, clinical and biological factors on outcomes in elderly GBM patients treated with surgery followed by concurrent radiation (RT) and Temozolomide (TMZ). MATERIALS AND METHODS: Our sample includes 34 elderly patients with GBM who treated from January 2013 to December 2017. We collected data regarding age, extension of surgery, use of current medications, KPS, presenting symptoms, Prognostic Nutritional Index (PNI), Charlson Co-morbidity Index (CCI) and Frailty Index (FI). All of these parameters, measured before the start of RT-TMZ, were linked to clinical outcomes. RESULTS: With a median follow-up of 9.7 months, the median overall survival (OS) was 12.1 months and 1-year OS was 50%. In univariable analysis high KPS and total surgery were significantly associated with better OS. Also PNI, CCI and FI were a significant predictors of OS. At multivariate analysis KPS, type of surgery and FI remained a significant predictors of OS and, based on these parameters, we generated a prognostic score that, dividing patients into three risk categories, has proven to be a survival predictor, with an increase of the risk of death by 2.2 times for each increment of the score (HR 2.2, p = .0004). CONCLUSION: The appropriate management of elderly cancer patients with GBM is an important concern in oncology. Our data suggest that in elderly patients in good clinical conditions and with a low FI score, extensive surgery, when feasible without adding neurological impairment, followed by adjuvant RT-TMZ, should be considered.