筛查是指在个体出现症状之前发现癌症。这有助于在早期发现癌症。早期发现异常组织或癌症，可能使治疗更为容易。当症状出现时，癌症可能已经开始扩散。
科学家正在进一步研究哪些人更有可能患某种类型的癌症。同时，他们也研究我们的生活方式和周围环境是否会导致癌症。这些信息有助于医生建议哪些人应该接受癌症的筛查，应该使用哪种筛查方法，以及应该多久做一次筛查。
重要的是请记住，如果医生建议你进行癌症筛查，他或她并没有一定认为你患有癌症。筛查检测是在你没有癌症症状时进行的。
如果筛查结果异常，您可能需要接受更多的检查来确定是否患有癌症。这些检查被称为诊断性检查。
Screening is looking for cancer before a person has any symptoms. This can help find cancer at an early stage. When abnormal tissue or cancer is found early, it may be easier to treat. By the time symptoms appear, cancer may have begun to spread.
Scientists are trying to better understand which people are more likely to get certain types of cancer. They also study the things we do and the things around us to see if they cause cancer. This information helps doctors recommend who should be screened for cancer, which screening tests should be used, and how often the tests should be done.
It is important to remember that your doctor does not necessarily think you have cancer if he or she suggests a screening test. Screening tests are given when you have no cancer symptoms.
If a screening test result is abnormal, you may need to have more tests done to find out if you have cancer. These are called diagnostic tests.
肺癌是一种恶性细胞在肺组织中形成的疾病。
肺是一对锥形的呼吸器官，位于胸腔内。人吸气时肺将氧气送入体内，呼气时肺将二氧化碳排出体外。每侧肺都可再分为叶。左肺有两叶，右肺稍大，有三叶。肺表面覆有一层薄膜，称为胸膜。气管分出两根支气管，分别通往右肺和左肺。支气管有时也可发生肺癌。肺内部由小管和小气囊组成，分别称为细支气管和肺泡。
肺癌有两种类型：小细胞肺癌和非小细胞肺癌。
更多关于肺癌的信息，请参阅以下PDQ总结:
在美国，肺癌是癌症死亡的主要原因。在中国，肺癌也是癌症死亡的首要原因。
肺癌是美国第三大常见的非皮肤癌。肺癌是男性和女性癌症死亡的主要原因。肺癌是中国第一大常见的癌症。肺癌是男性和女性癌症死亡的首要要原因。
不同的因素可增加或减少肺癌的发生危险。
任何可增加疾病发生几率的因素都称为危险因素。任何可降低疾病发生几率的因素都称为保护性因素。
关于肺癌危险因素和保护性因素的信息，请参阅关于肺癌预防的PDQ总结。
Lung cancer is a disease in which malignant (cancer) cells form in the tissues of the lung.
The lungs are a pair of cone-shaped breathing organs inside the chest. The lungs bring oxygen into the body when breathing in and send carbon dioxide out of the body when breathing out. Each lung has sections called lobes. The left lung has two lobes. The right lung, which is slightly larger, has three. A thin membrane called the pleura surrounds the lungs. Two tubes called bronchi lead from the trachea (windpipe) to the right and left lungs. The bronchi are sometimes involved in lung cancer. Small tubes called bronchioles and tiny air sacs called alveoli make up the inside of the lungs.
There are two types of lung cancer: small cell lung cancer and non-small cell lung cancer.
See the following PDQ summaries for more information about lung cancer:
Lung cancer is the leading cause of cancer death in the United States.
Lung cancer is the third most common type of non-skin cancer in the United States. Lung cancer is the leading cause of cancer death in men and in women.
Different factors increase or decrease the risk of lung cancer.
Anything that increases your chance of getting a disease is called a risk factor. Anything that decreases your chance of getting a disease is called a protective factor.
For information about risk factors and protective factors for lung cancer, see the PDQ summary on Lung Cancer Prevention.
当人体没有症状时，可以用检查或试验来筛查不同类型的癌症。
科学家对筛查试验进行研究，从而发现伤害最小而获益最大的筛查方法。开展癌症筛查试验的目的也是为了证明早期发现（在出现症状前发现癌症）是否有助于延长生命或降低死于该病的风险。对于某些类型的癌症，如果能在早期发现并治疗，康复的机会会更大。
研究人员对三种肺癌的筛查方法进行了评估，以确定它们是否能降低肺癌的死亡风险。
研究人员对下列筛查试验进行了研究，以了解它们是否能降低死于肺癌的风险:
低剂量螺旋CT扫描已被证明可以降低重度吸烟者死于肺癌的风险。
美国国家肺癌筛查试验是在55-74岁的重度吸烟者中进行的，这些重度吸烟者每天至少吸1包烟，持续30年或更长时间。此试验也纳入了戒烟时间少于15年的重度吸烟者。此试验利用胸部x线检查或LDCT扫描来筛查肺癌。
在发现早期肺癌方面，LDCT扫描优于胸部x光检查。LDCT筛查还可降低现在和既往重度吸烟者死于肺癌的风险。
LDCT扫描结果显示疑似有癌症迹象的当前吸烟者更可能戒烟。
目前已有肺癌筛查的指南，可供患者和医生来了解更多关于肺癌低剂量螺旋CT筛查的获益和危害。
胸部X线检查和/或痰液细胞学筛查并不能降低肺癌的死亡风险。
胸部X线检查和痰细胞学检查是两种肺癌筛查方法。胸部X线筛查、痰细胞学筛查、或者二者的联合应用，均不能降低肺癌的死亡风险。
肺癌的筛查试验正在临床试验中进行研究。
关于NCI支持的临床试验信息，可以在NCI临床试验搜索网页上查询。其他组织支持的临床试验可在ClinicalTrials.gov网站上查询。
Tests are used to screen for different types of cancer when a person does not have symptoms.
Scientists study screening tests to find those with the fewest harms and most benefits. Cancer screening trials also are meant to show whether early detection (finding cancer before it causes symptoms) helps a person live longer or decreases a person's chance of dying from the disease. For some types of cancer, the chance of recovery is better if the disease is found and treated at an early stage.
Three screening tests have been studied to see if they decrease the risk of dying from lung cancer.
The following screening tests have been studied to see if they decrease the risk of dying from lung cancer:
Screening with low-dose spiral CT scans has been shown to decrease the risk of dying from lung cancer in heavy smokers.
The National Lung Screening Trial studied people aged 55 years to 74 years who had smoked at least 1 pack of cigarettes per day for 30 years or more. Heavy smokers who had quit smoking within the past 15 years were also studied. The trial used chest x-rays or LDCT scans to check for signs of lung cancer.
LDCT scans were better than chest x-rays at finding early-stage lung cancer. Screening with LDCT also decreased the risk of dying from lung cancer in current and former heavy smokers.
Current smokers whose LDCT scan result shows possible signs of cancer may be more likely to quit smoking.
A Guide is available for patients and doctors to learn more about the benefits and harms of low-dose helical CT screening for lung cancer.
Screening with chest x-rays and/or sputum cytology does not decrease the risk of dying from lung cancer.
Chest x-ray and sputum cytology are two screening tests that have been used to check for signs of lung cancer. Screening with chest x-ray, sputum cytology, or both of these tests does not decrease the risk of dying from lung cancer.
Screening tests for lung cancer are being studied in clinical trials.
Information about clinical trials supported by NCI can be found on NCI’s clinical trials search webpage. Clinical trials supported by other organizations can be found on the ClinicalTrials.gov website.
筛查试验存在风险。
对于是否参加筛查，往往很难做出抉择。并非所有的筛查试验都会有帮助，而且大多数都存在风险。在接受任何筛查之前，你需要咨询医生。了解筛查试验的风险及该筛查试验是否已被证实可降低癌症的死亡风险非常重要。
肺癌筛查的风险包括以下方面:
发现肺癌可能不会改善健康或帮助延长生命。
如果你已患肺癌并且已转移至身体其他部位，筛查可能不会改善你的健康状况，也不会延长你的寿命。
当一种疾病由筛查检出，并进行了治疗，但这种疾病可能永远不会产生症状或危及生命时，这种情况被称为过度诊断。目前不确定对这些癌症进行治疗是否会较不治疗更能延长生命，并且癌症治疗可能存在严重的副作用。在因重度或长期吸烟而发生疾病的个体中，更易发生癌症治疗相关的危害。
可能会出现假阴性结果。
即使肺癌已经存在，筛查试验结果仍可能提示正常。当筛查结果为假阴性（肺癌真实存在，但结果却提示无肿瘤）时，即使已经出现症状，患者都可能会延迟就医。
也可能出现假阳性筛查结果。
即使没有肺癌，筛查试验仍可能提示异常。假阳性试验结果（无肺癌时，筛查结果却提示肺癌）可导致焦虑，且通常需要进行更多后续的检查（例如活检），而这些检查也存在风险。肺癌活检可导致部分肺塌陷。有时需要手术使肺重新充气。即使没有癌症，筛查测试结果也可能看起来异常。 在因大量或长期吸烟而引起医疗问题的患者中，诊断测试的错误危害可能更经常发生。
胸部x线和低剂量螺旋CT扫描使胸部暴露于辐射。
胸部x线检查和低剂量螺旋CT的辐射暴露可能会增加癌症的风险。年轻人和肺癌低风险人群更容易因辐射暴露导致肺癌。
关于患肺癌的风险以及是否需要参加筛查试验，请咨询你的医生。
关于你的肺癌患病风险，是否适合做筛查，以及筛查试验的获益和危害，请咨询医生或其他医疗人员。你应该参与筛查试验的决定，确定其是否适合你。（更多信息请参阅关于癌症筛查综述的PDQ总结。）
Screening tests have risks.
Decisions about screening tests can be difficult. Not all screening tests are helpful and most have risks. Before having any screening test, you may want to discuss the test with your doctor. It is important to know the risks of the test and whether it has been proven to reduce the risk of dying from cancer.
The risks of lung cancer screening tests include the following:
Finding lung cancer may not improve health or help you live longer.
Screening may not improve your health or help you live longer if you have lung cancer that has already spread to other places in your body.
When a screening test result leads to the diagnosis and treatment of a disease that may never have caused symptoms or become life-threatening, it is called overdiagnosis. It is not known if treatment of these cancers would help you live longer than if no treatment were given, and treatments for cancer may have serious side effects. Harms of treatment may happen more often in people who have medical problems caused by heavy or long-term smoking.
False-negative test results can occur.
Screening test results may appear to be normal even though lung cancer is present. A person who receives a false-negative test result (one that shows there is no cancer when there really is) may delay seeking medical care even if there are symptoms.
False-positive test results can occur.
Screening test results may appear to be abnormal even though no cancer is present. A false-positive test result (one that shows there is cancer when there really isn't) can cause anxiety and is usually followed by more tests (such as biopsy), which also have risks. A biopsy to diagnose lung cancer can cause part of the lung to collapse. Sometimes surgery is needed to reinflate the lung. Harms of diagnostic tests may happen more often in patients who have medical problems caused by heavy or long-term smoking.
Chest x-rays and low-dose spiral CT scans expose the chest to radiation.
Radiation exposure from chest x-rays and low-dose spiral CT scans may increase the risk of cancer. Younger people and people at low risk for lung cancer are more likely to develop lung cancer caused by radiation exposure. .
Talk to your doctor about your risk for lung cancer and your need for screening tests.
Talk to your doctor or other health care provider about your risk for lung cancer, whether a screening test is right for you, and about the benefits and harms of the screening test. You should take part in the decision about whether a screening test is right for you. (See the PDQ summary on Cancer Screening Overview for more information.)
Physician Data Query (PDQ) is the National Cancer Institute's (NCI's) comprehensive cancer information database. The PDQ database contains summaries of the latest published information on cancer prevention, detection, genetics, treatment, supportive care, and complementary and alternative medicine. Most summaries come in two versions. The health professional versions have detailed information written in technical language. The patient versions are written in easy-to-understand, nontechnical language. Both versions have cancer information that is accurate and up to date and most versions are also available in Spanish.
PDQ is a service of the NCI. The NCI is part of the National Institutes of Health (NIH). NIH is the federal government’s center of biomedical research. The PDQ summaries are based on an independent review of the medical literature. They are not policy statements of the NCI or the NIH.
This PDQ cancer information summary has current information about lung cancer screening. It is meant to inform and help patients, families, and caregivers. It does not give formal guidelines or recommendations for making decisions about health care.
Editorial Boards write the PDQ cancer information summaries and keep them up to date. These Boards are made up of experts in cancer treatment and other specialties related to cancer. The summaries are reviewed regularly and changes are made when there is new information. The date on each summary ("Updated") is the date of the most recent change.
The information in this patient summary was taken from the health professional version, which is reviewed regularly and updated as needed, by the PDQ Screening and Prevention Editorial Board.
A clinical trial is a study to answer a scientific question, such as whether one treatment is better than another. Trials are based on past studies and what has been learned in the laboratory. Each trial answers certain scientific questions in order to find new and better ways to help cancer patients. During treatment clinical trials, information is collected about the effects of a new treatment and how well it works. If a clinical trial shows that a new treatment is better than one currently being used, the new treatment may become "standard." Patients may want to think about taking part in a clinical trial. Some clinical trials are open only to patients who have not started treatment.
Clinical trials can be found online at NCI's website. For more information, call the Cancer Information Service (CIS), NCI's contact center, at 1-800-4-CANCER (1-800-422-6237).
PDQ is a registered trademark. The content of PDQ documents can be used freely as text. It cannot be identified as an NCI PDQ cancer information summary unless the whole summary is shown and it is updated regularly. However, a user would be allowed to write a sentence such as “NCI’s PDQ cancer information summary about breast cancer prevention states the risks in the following way: [include excerpt from the summary].”
The best way to cite this PDQ summary is:
PDQ® Screening and Prevention Editorial Board. PDQ Lung Cancer Screening. Bethesda, MD: National Cancer Institute. Updated
Images in this summary are used with permission of the author(s), artist, and/or publisher for use in the PDQ summaries only. If you want to use an image from a PDQ summary and you are not using the whole summary, you must get permission from the owner. It cannot be given by the National Cancer Institute. Information about using the images in this summary, along with many other images related to cancer can be found in Visuals Online. Visuals Online is a collection of more than 3,000 scientific images.
The information in these summaries should not be used to make decisions about insurance reimbursement. More information on insurance coverage is available on Cancer.gov on the Managing Cancer Care page.
More information about contacting us or receiving help with the Cancer.gov website can be found on our Contact Us for Help page. Questions can also be submitted to Cancer.gov through the website’s E-mail Us.
Physician Data Query (PDQ) is the National Cancer Institute's (NCI's) comprehensive cancer information database. The PDQ database contains summaries of the latest published information on cancer prevention, detection, genetics, treatment, supportive care, and complementary and alternative medicine. Most summaries come in two versions. The health professional versions have detailed information written in technical language. The patient versions are written in easy-to-understand, nontechnical language. Both versions have cancer information that is accurate and up to date and most versions are also available in Spanish.
PDQ is a service of the NCI. The NCI is part of the National Institutes of Health (NIH). NIH is the federal government’s center of biomedical research. The PDQ summaries are based on an independent review of the medical literature. They are not policy statements of the NCI or the NIH.
This PDQ cancer information summary has current information about lung cancer screening. It is meant to inform and help patients, families, and caregivers. It does not give formal guidelines or recommendations for making decisions about health care.
Editorial Boards write the PDQ cancer information summaries and keep them up to date. These Boards are made up of experts in cancer treatment and other specialties related to cancer. The summaries are reviewed regularly and changes are made when there is new information. The date on each summary ("Updated") is the date of the most recent change.
The information in this patient summary was taken from the health professional version, which is reviewed regularly and updated as needed, by the PDQ Screening and Prevention Editorial Board.
A clinical trial is a study to answer a scientific question, such as whether one treatment is better than another. Trials are based on past studies and what has been learned in the laboratory. Each trial answers certain scientific questions in order to find new and better ways to help cancer patients. During treatment clinical trials, information is collected about the effects of a new treatment and how well it works. If a clinical trial shows that a new treatment is better than one currently being used, the new treatment may become "standard." Patients may want to think about taking part in a clinical trial. Some clinical trials are open only to patients who have not started treatment.
Clinical trials can be found online at NCI's website. For more information, call the Cancer Information Service (CIS), NCI's contact center, at 1-800-4-CANCER (1-800-422-6237).
PDQ is a registered trademark. The content of PDQ documents can be used freely as text. It cannot be identified as an NCI PDQ cancer information summary unless the whole summary is shown and it is updated regularly. However, a user would be allowed to write a sentence such as “NCI’s PDQ cancer information summary about breast cancer prevention states the risks in the following way: [include excerpt from the summary].”
The best way to cite this PDQ summary is:
PDQ® Screening and Prevention Editorial Board. PDQ Lung Cancer Screening. Bethesda, MD: National Cancer Institute. Updated
Images in this summary are used with permission of the author(s), artist, and/or publisher for use in the PDQ summaries only. If you want to use an image from a PDQ summary and you are not using the whole summary, you must get permission from the owner. It cannot be given by the National Cancer Institute. Information about using the images in this summary, along with many other images related to cancer can be found in Visuals Online. Visuals Online is a collection of more than 3,000 scientific images.
The information in these summaries should not be used to make decisions about insurance reimbursement. More information on insurance coverage is available on Cancer.gov on the Managing Cancer Care page.
More information about contacting us or receiving help with the Cancer.gov website can be found on our Contact Us for Help page. Questions can also be submitted to Cancer.gov through the website’s E-mail Us.