VOA健康报道2022--血液检测能拯救癌症患者的生命吗?

Can Cancer Blood Tests Help Save Lives?

Joyce Ares was feeling fine when she agreed to get a blood test for research. So, she was surprised when the test came back with signs of cancer.

After a repeat blood test and two more tests for cancer, she was found to have Hodgkin lymphoma.

"I cried," the 74-year-old retiree said. "Just a couple of tears and thought, ‘OK, now what do we do?'"

Ares had volunteered to take a blood test that is being viewed as a new way to check for cancer among healthy people. It looks for cancer by checking for DNA¹ parts broken from shed cancerous cells.

Such blood tests, called liquid biopsies, are already used in patients with cancer to establish treatment and check to see if cancerous growths come back.

Several drug companies are pushing for the blood test as part of regular health screening to find cancerous growths, or tumors, in certain parts of the body.

Grail, a California-based company, is far ahead of others with 2,000 doctors willing to prescribe the $949 test. Most insurance plans do not cover the cost.

The Food and Drug Administration demands an extensive study of a drug or vaccine³ before approval. A review by the agency is not required for this kind of blood test. But Grail plans to seek approval from the FDA while it is marketing⁴ the tests.

Experts are not sure whether the tests could improve Americans' health or help cut the cancer death rate. U.S. government researchers, meanwhile, are planning a large trial with 200,000 volunteers over seven years to study the blood tests.

"They sound wonderful, but we don't have enough information," said Dr. Lori Minasian of the National Cancer Institute. She is involved in planning the research. "We don't have definitive⁵ data that shows that they will reduce the risk of dying from cancer."

Cancer screening

The history of cancer screening has served as a warning.

In 2004, Japan halted mass screening of infants for childhood cancer after studies found it did not save lives. Last year, a 16-year study of 200,000 women in Britain found regular screening for ovarian cancer did not make any difference in deaths.

Cases like these have uncovered some surprises: Screening finds some cancers that do not need treatment. On the other side, many tumors spread so fast that they prove to be deadly anyway.

Cancer screening, at times, can do more harm than good. It leads to worry over false positives, unnecessary costs, and serious side effects from cancer care.

Dr. Joshua Ofman is an official with Grail. He said current screening tests only look for one kind of cancer at a time, including breast, cervix, colon⁶ or lung. The new blood tests look for many cancers at once.

"We screen for four or five cancers in this country, but (many) cancer deaths are coming from cancers that we're not looking for at all," Ofman said.

Dr. Tomasz Beer of Oregon Health & Science University in Portland led the Grail study that Joyce Ares joined in 2020. After chemotherapy and radiation, doctors told her the treatment was a success.

Beer said Ares' case is a "hoped-for ideal outcome." He added, "not everyone is going to have that." For some, Beer said the blood tests could bring false positives. For others, the tests found cancer that turned out to be advanced and aggressive.

Grail continues to update its test as it learns from these studies. The company is also working with Britain's National Health Service on a study of 140,000 people. They want to see if the blood test can reduce the number of advanced cancers.

Although Ares feels lucky, it is impossible to know whether her test added healthy years to her life or made no real difference, said Kramer, former director of the National Cancer Institute's Division of Cancer Prevention.

"I sincerely hope that Joyce benefited from having this test," Kramer said when told of her experience. "But unfortunately, we can't know, at the individual Joyce level, whether that's the case."

Cancer treatments can have long-term side effects, he said, "and we don't know how fast the tumor² would have grown." Treatment for Hodgkin lymphoma is very effective. It is possible that Joyce would have had the same good results if she had sought treatment only after she showed symptoms.

For now, health experts say the Grail blood test is not a cancer diagnosis⁷. "This is a path in diagnostic testing that has never been tried before," Kramer said. "Our ultimate destination is a test that has a clear net benefit. If we don't do it carefully, we'll go way off the path."

Words in this Story

shed – v. to lose naturally

ovarian - adj. of or related to ovary (an organ in woman's body that produce eggs and female hormones)

sincerely – adv. genuinely or truly

benefit – v. to be helped

diagnosis – n. the act of identifying a disease or illness

ultimate – adj. happening at the end

1 DNA   

(缩)deoxyribonucleic acid 脱氧核糖核酸

参考例句：

• DNA is stored in the nucleus of a cell.脱氧核糖核酸储存于细胞的细胞核里。
• Gene mutations are alterations in the DNA code.基因突变是指DNA密码的改变。

2 tumor   

n.（肿）瘤，肿块(英)tumour

参考例句：

• He was died of a malignant tumor.他死于恶性肿瘤。
• The surgeons irradiated the tumor.外科医生用X射线照射那个肿瘤。

3 vaccine   

n.牛痘苗，疫苗；adj.牛痘的，疫苗的

参考例句：

• The polio vaccine has saved millions of lives.脊髓灰质炎疫苗挽救了数以百万计的生命。
• She takes a vaccine against influenza every fall.她每年秋季接种流感疫苗。

4 marketing   

n.行销，在市场的买卖，买东西

参考例句：

• They are developing marketing network.他们正在发展销售网络。
• He often goes marketing.他经常去市场做生意。

5 definitive   

adj.确切的，权威性的；最后的，决定性的

参考例句：

• This book is the definitive guide to world cuisine.这本书是世界美食的权威指南。
• No one has come up with a definitive answer as to why this should be so.至于为什么该这样，还没有人给出明确的答复。

6 colon   

n.冒号，结肠，直肠

参考例句：

• Here,too,the colon must be followed by a dash.这里也是一样，应当在冒号后加破折号。
• The colon is the locus of a large concentration of bacteria.结肠是大浓度的细菌所在地。

7 diagnosis   

n.诊断，诊断结果，调查分析，判断

参考例句：

• His symptoms gave no obvious pointer to a possible diagnosis.他的症状无法作出明确的诊断。
• The engineer made a complete diagnosis of the bridge's collapse.工程师对桥的倒塌做一次彻底的调查分析。