山西医科大学研究生毕业专业英语题.doc

一、英译汉（80分，要求全部段落进行概要性翻译） 1. 第一部分（40分） The tumor-associated microenvironment, which consists of extracellular matrix (ECM), cancer-associated fibroblasts (CAFs), inflammatory immune cells, and tumor-associated vasculature, plays a critical role during tumorigenesis. CAFs, which are abundant in tumor-associated stroma, secrete several factors, including HGF and SDF1, to promote epithelial cell neoplastic transformation and cancer cell proliferation. In addition, CAFs interact with other stromal components to stimulate tumor-enhancing inflammation and angiogenesis. Moreover, ECM remodeling by CAFs is essential for tumor cell invasion and metastasis. Although CAFs are important constituents of the tumor stroma, the paracrine signals that mediate direct crosstalk between CAFs and tumor cells in metastasis are poorly understood. Exosomes are membrane vesicles that originate in large multivesicular bodies (MVBs) and are released in the extracellular milieu upon fusion of MVBs with the plasma membrane. Exosomes have the same topology as a cell and contain a broad array of biologically active material. Several cellular components of the tumor microenvironment and cancer cells secrete exosomes that function in an autocrine or paracrine manner to promote tumor-induced immune suppression, angiogenesis, and premetastatic niche formation. Currently, it is unknown whether CAFs secrete exosomes and whether these microvesicles support cancer cell metastasis. 2. 第二部分（20分） Because the spectrum of cancer care includes screening as well as treatment, a comprehensive understanding of breast cancer cost must incorporate the cost of screening and associated workup. While the body of evidence concerning Medicare expenditures for cancer treatment has grown, relatively little is known about cost associated with screening Medicare beneficiaries for breast cancer. This is especially important among older women because recent guidelines have concluded that there is insufficient evidence to asses