Imatinib as preoperative therapy in Chinese patients with recurrent or metastatic GISTs

Objective： Imatinib has dramatically altered the options for management of patients with gastrointestinal stromal turnouts. However, it has become clear that secondary resistance to the drug develops during long- term therapy. The purpose of our study was to retrospectively analyze safety and long-term outcomes in Chinese patients with recurrent or metastatic GISTs treated with imatinib preoperatively. Methods： Between June 2003 and June 2011, 22 patients underwent surgery for recurrent or metastatic GISTs after preoperative treatment with imatinib. Results： Complete resection was accomplished in 8 of the 10 responsive disease （RD） patients （80%）, and in 3 of the 12 patients （25%） who had progression disease （PD）. The amount of blood loss during the operation in PD patients was higher than in RD patients. There was 1 hospital death in PD group related to surgery, while the other patients recovered with conservative therapy because complications were mild. The difference in median PFS between patients with RD and those with PD was significant （24.8 vs. 2.81 months, P〈0.001）. The difference in 2-year OS rate between patients with RE） and those with PD was not significant （100% vs. 87.5%, P〉0.05）. Conclusions： Our study indicates that surgical intervention can improve the PFS of Chinese patients with recurrent or metastatic GISTs responsive to imatinib, but does not prolong OS as well as in patients who develop imatinib resistance. Surgical resection following imatinib treatment is feasible and can be considered for patients with advanced GISTs responsive to imatinib.

THE RECONSTRUCTION OF OBSTACLES IN A WAVEGUIDE USING FINITE ELEMENTS

This paper concerns the reconstruction of a penetrable obstacle embedded in a waveg- uide using the scattered data due to point sources, which is formulated as an optimization problem. We propose a fast reconstruction method based on a carefully designed finite element scheme for the direct scattering problem. The method has several merits： 1） the linear sampling method is used to quickly obtain a good initial guess; 2） finite Fourier series are used to approximate the boundary of the obstacle, which is decoupled from the boundary used by the finite element method; and 3） the mesh is fixed and hence the stiff- ness matrix, mass matrix, and right hand side are assembled once and only minor changes are made at each iteration. The effectiveness of the proposed method is demonstrated by numerical examples.

A NEW INTEGRAL EQUATION FORMULATION FOR SCATTERING BY PENETRABLE DIFFRACTION GRATINGS

This paper is concerned with the problem of scattering of time-harmonic electromag- netic waves from penetrable diffraction gratings in the 2D polarization case. We propose a new, weakly singular, integral equation formulation for the scattering problem which is proved to be uniquely solvable. A main feature of the new integral equation formula- tion is that it avoids the computation of the normal derivative of double-layer potentials which is difficult and time consuming. A fast numerical algorithm is also developed for the scattering problem, based on the NystrSm method for the new integral equation. Nu- merical examples are also shown to illustrate the applicability of the new integral equation formulation.

Treatment and prognosis of iliac fossa soft tissue sarcoma: A single-center study

Dear Editor,Primary iliac fossa sarcoma(IFS)is a special type of retroperitoneal sarcoma(RPS),accounting for∼15%of all RPS cases[1].The deep location,large size,and invasion to surrounding tissues and organs are the main causes of unresectability of IFS.All these characteristics are associated with an increased risk of positive surgical margin and a decreased feasibility of adjuvant therapy.In patients with multivisceral and/or vascular involvement,a multivisceral en bloc approach[2]with blood vessel replacement may be required to achieve a negative margin and to improve the quality of resection[3].However,whether these surgical procedures improve prognosis in patients with IFS remain undefined.Moreover,whether aggressive procedures lead to acceptable functional impairment requires validation.In addition,previous studies have reported inconsistent results regarding the role of adjuvant radiotherapy in the treatment of RPS[4].To date,the role of radiotherapy in the local control of IFS remains to be determined.Therefore,we analyzed the clinical features,treatment,and outcomes of IFS patients in an attempt to determine the significant prognostic factors and efficient therapeutics in real clinical practice.