The effect of tensile and fluid shear stress on the in vitro degradation of magnesium alloy for stent applications.

Magnesium alloys have gained great attention as biodegradable materials for stent applications. Cardiovascular stents are continuously exposed to different types of mechanical loadings simultaneously during service, including tensile, compressive and fluid shear stress. In this study, the in vitro degradation of WE43 wires was investigated under combined effect of tensile loading and fluid shear stress and compared with that experienced an individual loading condition. For the individual mechanical loading treatment, the degradation of magnesium wires was more severely affected by tensile loading than fluid shear stress. Under tensile loading, magnesium wires showed faster increment of corrosion rates, loss of mechanical properties and localized corrosion morphology with the increasing tensile loadings. With the combined stress, smaller variation of the corrosion rates as well as the slower strength degeneration was shown with increasing stress levels, in comparison with the individual treatment of tensile loading. This study could help to understand the effect of complex stress condition on the corrosion of magnesium for the optimization of biodegradable magnesium stents.

Role of Recursive Partitioning Analysis and Graded Prognostic Assessment on Identifying Non-Small Cell Lung Cancer Patients with Brain Metastases Who May Benefit from Postradiation Systemic Therapy.

BACKGROUND: The role of postradiation systemic therapy in non-small cell lung cancer (NSCLC) patients with brain metastasis (BM) was controversial. Thus, we explored the role of Radiation Therapy Oncology Group recursive partitioning analysis (RTOG-RPA) and graded prognostic assessment (GPA) in identifying population who may benefit from postradiation systemic therapy. METHODS: The clinical data of NSCLC patients with documented BM from August 2007 to April 2015 of two hospitals were studied retrospectively. Cox regression was used for multivariate analysis. Survival of patients with or without postradiation systemic therapy was compared in subgroups stratified according to RTOG-RPA or GPA. RESULTS: Of 216 included patients, 67.1% received stereotactic radiosurgery (SRS), 24.1% received whole-brain radiation therapy (WBRT), and 8.8% received both. After radiotherapy, systemic therapy was administered in 58.3% of patients. Multivariate analysis found that postradiation systemic therapy (yes vs. no) (hazard ratio [HR] = 0.361, 95% confidence interval [CI] = 0.202-0.648, P = 0.001), radiation technique (SRS vs. WBRT) (HR = 0.462, 95% CI = 0.238-0.849, P = 0.022), extracranial metastasis (yes vs. no) (HR = 3.970, 95% CI = 1.757-8.970, P = 0.001), and Karnofsky performance status (<70 vs. ≥70) (HR = 5.338, 95% CI = 2.829-10.072, P < 0.001) were independent factors for survival. Further analysis found that subsequent tyrosine kinase inhibitor (TKI) therapy could significantly reduce the risk of mortality of patients in RTOG-RPA Class II (HR = 0.411, 95% CI = 0.183-0.923, P = 0.031) or with a GPA score of 1.5-2.5 (HR = 0.420, 95% CI = 0.182-0.968, P = 0.042). However, none of the subgroups stratified according to RTOG-RPA or GPA benefited from the additional conventional chemotherapy. CONCLUSION: RTOG-RPA and GPA may be useful to identify beneficial populations in NSCLC patients with BM if TKIs were chosen as postradiation systemic therapy.

Systemic Therapy after Radiotherapy Significantly Reduces the Risk of Mortality of Patients with 1-3 Brain Metastases: A Retrospective Study of 250 Patients.

BACKGROUND: For patients with a brain metastasis (BM), systemic therapy is usually administered after the completion of radiotherapy, especially in cases of multiple BMs. However, the role of systemic therapy in patients with a limited number of BMs is not clear. Therefore, we conducted a retrospective study to explore this question. METHODS: Consecutive patients with a pathologically confirmed malignancy and 1-3 intracranial lesions that had been documented within the last decade were selected from the databases of three hospitals in China. RESULTS: A total of 250 patients were enrolled; of them, 135 received radiotherapy alone and 115 received radiotherapy plus systemic therapy. In patients receiving whole-brain radiation therapy (WBRT) as radiotherapy, 28 received WBRT alone and 35 patients received WBRT plus systemic therapy. Of the patients treated with stereotactic radiosurgery (SRS), 107 received SRS alone and 80 received SRS plus systemic therapy. Multivariate analysis revealed that systemic therapy significantly reduced the risk of mortality compared with radiotherapy alone (hazard ratio [HR] = 0.294, 95% confidence interval [CI] = 0.158-0.548). Further, when the analysis was conducted in subgroups of WBRT (HR = 0.230, 95% CI = 0.081-0.653) or SRS (HR = 0.305, 95% CI = 0.127-0.731), systemic therapy still showed the ability to reduce the risk of mortality in patients with BMs. CONCLUSION: Systemic therapy after either SRS or WBRT radiotherapy may significantly reduce the risk of mortality of patients with 1-3 BMs.