問題詳情

第二篇   Most cancers are detected by a cell biopsy, where a sample of the cancerous tissue is examined under amicroscope. However, researchers in the US have reported that they are a step closer to developing a cancer screeningtool that requires just a sample of blood. The test, dubbed CancerSEEK, was developed by Johns Hopkins University,Baltimore. It looks for 16 DNA mutations commonly associated with cancer as well as eight proteins associated withcancer.   CancerSEEK was tested on 1,000 patients with cancers in the ovary, liver, stomach, pancreas, oesophagus, colon,lung or breast. The cancers were at stage one to three and had not spread to other parts of the body. The scientistsreported that the test was 70% accurate at spotting people with cancer. Importantly, the test raised few false positives.In other words, it only“found”cancer in seven out of 812 healthy control subjects. This proof-of-concept study isimportant because it proves the feasibility of developing a fairly non-invasive and potentially inexpensive test in blood.And it is exciting because it confirms the usefulness of simultaneously looking for a combination of differentmolecules—such as DNA, RNA, proteins or metabolites—that are complementary and increase the likelihood ofdetecting cancer.   The drawback of this study is that it is retrospective. Blood samples were taken from patients already diagnosedwith cancer. And, although the test detects tumors that can be removed by surgery, they were not early stage tumors.Only around 40% of stage one cancers were detected. The test also appear to be least sensitive for two of the mostcommon cancers (lung and breast), although this is probably due to the selection of biomarkers and can be furtherimproved on. Another limitation is that the test doesn’t tell where the cancer is located, but this could probably also beimproved in future versions of the test by including of other variables in the model, such as symptoms or additionalbiomarkers.   As a proof of principle, this is an important and exciting study, but, before the new diagnostic tool is madeavailable in hospitals and clinics, it will need to satisfy the requirements for any new test: rigorous further evaluationin large trials that would prove its effectiveness and usefulness as a cancer-screening tool.
36. What is the main purpose of the passage?
(A) To summarize a study on CancerSEEK.
(B) To describe the contributions of CancerSEEK.
(C) To introduce a formal procedure for CancerSEEK.
(D) To evaluate the economic benefits of CancerSEEK.

參考答案

答案：A
難度：適中0.5
統計：A(0),B(0),C(0),D(0),E(0)

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