什么是筛查？
筛查是在个体出现症状之前发现癌症，以便帮助我们发现早期癌症。当癌前病变或者癌症在早期被发现时，它可能会更容易被治疗。等到有症状出现时，癌细胞可能已经开始扩散。
科学家们正在尝试更好地了解哪些人更容易患上某种癌症。他们也在研究着我们的行为及周边环境是否会导致癌症。这些信息可以帮助医生建议哪些人应该接受癌症筛查，应该采用何种筛查方法及其检查频率。
值得注意的是，如果医生建议你做癌症筛查并非意味着你患有癌症。当你没有癌症症状时，可定期接受筛查。
如果你的筛查结果异常，你可能需要接受更多的检查来确诊你是否患有癌症，这叫做诊断性检查。
What is screening?
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. Screening tests may be repeated on a regular basis.
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.
关于结直肠癌的基本信息
结直肠癌是结肠或直肠组织中产生恶性（癌）细胞的一类疾病。
结肠和直肠是身体消化系统的一部分。消化系统由口腔、咽喉、食管、胃、小肠和大肠组成，对食物中的营养物质（维生素、矿物质、碳水化合物、脂肪、蛋白质和水）进行消化和吸收，并协助将粪便排出体外。结肠（大肠）是大肠的第一部分，长度约为5英尺。大肠的最后一部分由直肠和肛管组成，长度约为6-8英寸。肛管在肛门末端，是大肠通向体外的开口。
下消化系统的解剖图，显示结肠和其他器官。
发生在结肠上的癌症称为结肠癌，发生在直肠上的癌症称为直肠癌。同时发生在这两个部位的癌症也可以称为结直肠癌。
有关结直肠癌的更多信息，请参考以下PDQ总结：
结直肠癌是美国癌症死亡的第三大主要原因，也是中国癌症死亡的第三大主要原因。
55岁以上人群结直肠癌的新发病例和死亡病例数量每年略有下降。然而，近来年55岁以下人群结直肠癌的新发病和死亡病例数量小幅上升。男性结直肠癌患者人数多于女性。据估计，2015年中国结直肠癌新发病例38.8万例，死亡18.7万例，其中男性新发病例22.5万例，女性16.3万例，男性结直肠癌新发病例数多于女性。
不同因素会增加或减少患结直肠癌的风险。任何增加患病几率的因素都被称为危险因素，任何降低患病几率的因素都被称为保护因素。
如想了解更多有关结直肠癌的危险因素和保护因素的信息，请参阅结直肠癌预防的PDQ总结。
General Information About Colorectal Cancer
Colorectal cancer is a disease in which malignant (cancer) cells form in the tissues of the colon or the rectum.
The colon and rectum are parts of the body's digestive system. The digestive system removes and processes nutrients (vitamins, minerals, carbohydrates, fats, proteins, and water) from foods and helps pass waste material out of the body. The digestive system is made up of the mouth, throat, esophagus, stomach, and the small and large intestines. The colon (large bowel) is the first part of the large intestine and is about 5 feet long. Together, the rectum and anal canal make up the last part of the large intestine and are 6-8 inches long. The anal canal ends at the anus (the opening of the large intestine to the outside of the body).
Anatomy of the lower digestive system, showing the colon and other organs.
Cancer that begins in the colon is called colon cancer, and cancer that begins in the rectum is called rectal cancer. Cancer that begins in either of these organs may also be called colorectal cancer.
See the following PDQ summaries for more information about colorectal cancer:
Colorectal cancer is the third leading cause of death from cancer in the United States.
The number of new colorectal cancer cases and the number of deaths from colorectal cancer are decreasing a little bit each year in adults aged 55 years and older. But in adults younger than 55 years, there has been a small increase in the number of new cases and deaths from colorectal cancer in recent years. Colorectal cancer is found more often in men than in women.
Different factors increase or decrease the risk of getting colorectal 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 colorectal cancer, see the PDQ summary on Colorectal Cancer Prevention.
结直肠癌筛查
当一个人没有症状时，检查方法用于筛查不同类型的癌症。
科学家们正在探索危害最小和获益最大的筛查方法。癌症筛查试验的目的也是为证实早期检查(在产生症状之前发现癌症）能否延长人的寿命或降低癌症死亡率。对于某些类型的癌症，如果能在早期发现并治疗癌症，康复的机会更高。
研究表明，一些结直肠癌的筛查方法有助于实现早期发现癌症，并可能降低结直肠癌死亡人数。
用于结直肠癌筛查的五种检查方法:
粪便潜血试验
粪便潜血试验（FOBT）是一种通过显微镜检查粪便（固体废弃物）中是否有血的检查方法。将少量粪便样本置于一张特殊的卡片上或一个特殊的容器中，然后交给医生或检验室进行检测。粪便中有血提示可能存在息肉、癌症或其他疾病。
有两种类型的粪便潜血试验（FOBT）：
愈创木脂化学法粪便潜血试验（FOBT）检查粪便中是否有潜（隐）血。将少量粪便样本放置在特殊的卡片上，然后交给医生或检验室进行检测。
粪便免疫化学试验（FIT）是检查粪便中的潜（隐）血。将少量粪便样本置于一个特殊的收集管或特殊卡片上，然后交给医生或检验室进行检测。
乙状结肠镜检查
乙状结肠镜是一种用于探查直肠和乙状结肠（下段）内部息肉、病变或癌症的检查手段。乙状结肠镜是一个纤细的管状仪器，带有用于观察的灯和镜头，将其通过直肠插入到乙状结肠进行探查。它还可以用于切除息肉或组织样本，可在显微镜下判断是否有癌变。
乙状结肠镜检查。通过肛门和直肠将纤维内窥镜插入结肠下部，以查看异常部位。
结肠镜检查
结肠镜是一种用于探查直肠和结肠息肉、病变或癌症的检查手段。结肠镜是一种纤细的管状仪器，配有用于观察的灯和镜头，将其通过直肠插入结肠进行探查。它还可用于切除息肉或组织样本，用于在显微镜下判断有无癌变。
结肠镜检查。将纤维内窥镜穿过肛门和直肠插入结肠下段来检查异常。
虚拟结肠镜检查
虚拟结肠镜是一种使用x线（称为计算机断层扫描）来拍摄一系列的结肠图像的检查手段。计算机将这些图片重组为具体的图像，这些图像可以显示结肠内部的息肉和可疑病变。这种检查也被称为计算机断层扫描结肠镜检查或CTC。
目前，正在通过临床试验比较虚拟结肠镜检查与其他结直肠癌筛查方法。一些临床试验正在测试是否可以通过饮用造影剂，使造影剂包裹粪便，而不是使用泻药排空结肠，来清楚地显示息肉。
粪便DNA检测
这项检查用于检测粪便细胞中的基因变化，这可能是结直肠癌的生物标志物。
研究表明，通过直肠指检筛查结直肠癌，并没有降低结直肠癌死亡人数。
直肠指检（DRE）是一种直肠检查方法，可以作为常规体检的一部分。医生或护士将戴着手套、涂了润滑剂的手指插入直肠下部，以检查是否有肿块或其他异常情况。研究结果表明，DRE不能作为结直肠癌的筛查方法。
结直肠癌的筛查方法正在进行临床试验研究
有关NCI支持的临床试验的信息，可以查询NCI的临床试验搜索网页。其他组织支持的临床试验可以查询ClinicalTrials.gov网站。
Colorectal Cancer Screening
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.
Studies show that some screening tests for colorectal cancer help find cancer at an early stage and may decrease the number of deaths from the disease.
Five types of tests are used to screen for colorectal cancer:
Fecal occult blood test
A fecal occult blood test (FOBT) is a test to check stool (solid waste) for blood that can only be seen with a microscope. A small sample of stool is placed on a special card or in a special container and returned to the doctor or laboratory for testing. Blood in the stool may be a sign of polyps, cancer, or other conditions.
There are two types of FOBTs:
A guaiac fecal occult blood test (FOBT) checks for occult (hidden) blood in the stool. Small samples of stool are placed on a special card and returned to a doctor or laboratory for testing.
A fecal immunochemical test (FIT) checks for occult (hidden) blood in the stool. A small sample of stool is placed in a special collection tube or on special cards and returned to a doctor or laboratory for testing.
Sigmoidoscopy
Sigmoidoscopy is a procedure to look inside the rectum and sigmoid (lower) colon for polyps, abnormal areas, or cancer. A sigmoidoscope is inserted through the rectum into the sigmoid colon. A sigmoidoscope is a thin, tube-like instrument with a light and a lens for viewing. It may also have a tool to remove polyps or tissue samples, which are checked under a microscope for signs of cancer.
Sigmoidoscopy. A thin, lighted tube is inserted through the anus and rectum and into the lower part of the colon to look for abnormal areas.
Colonoscopy
Colonoscopy is a procedure to look inside the rectum and colon for polyps, abnormal areas, or cancer. A colonoscope is inserted through the rectum into the colon. A colonoscope is a thin, tube-like instrument with a light and a lens for viewing. It may also have a tool to remove polyps or tissue samples, which are checked under a microscope for signs of cancer.
Colonoscopy. A thin, lighted tube is inserted through the anus and rectum and into the colon to look for abnormal areas.
Virtual colonoscopy
Virtual colonoscopy is a procedure that uses a series of x-rays called computed tomography to make a series of pictures of the colon. A computer puts the pictures together to create detailed images that may show polyps and anything else that seems unusual on the inside surface of the colon. This test is also called computed tomography colonography or CTC.
Clinical trials are comparing virtual colonoscopy with other colorectal cancer screening tests. Some clinical trials are testing whether drinking a contrast material that coats the stool, instead of using laxatives to empty the colon, shows polyps clearly.
DNA stool test
This test checks DNA in stool cells for genetic changes that may be a sign of colorectal cancer.
Studies have shown that screening for colorectal cancer using digital rectal exam does not decrease the number of deaths from the disease.
A digital rectal exam (DRE) is an exam of the rectum that may be done as part of a routine physical exam. A doctor or nurse inserts a lubricated, gloved finger into the lower part of the rectum to feel for lumps or anything else that seems unusual. Study results have shown that DRE does not work as a screening method for colorectal cancer.
Screening tests for colorectal 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.
结直肠癌筛查的风险
筛查有风险
关于筛查方法的选择可能很困难，并不是所有的筛查方法都有利，而是许多检查具有风险。不同的筛查方法存在不同的风险或危害。当您在考虑或准备进行检查的时候，或者当检查结果呈阳性的时候，筛查可能会使您焦虑。在进行任何筛查之前，您可能需要咨询医生，很有必要了解清楚检查存在的风险以及是否有证据表明其可降低癌症的死亡风险。
咨询医生您患结直肠癌的风险以及是否需要进行筛查。
可能会出现假阴性检测结果
即使患有结直肠癌，筛查结果也可能为正常。一个人有症状，他的检查结果为假阴性（实际患有癌症，筛查结果却显示没有），可能会造成延误就医。
可能会出现假阳性检测结果
即使没得癌症，筛查结果可能会显示异常。假阳性检查结果（筛查结果显示有癌症，其实没有）会导致焦虑，且需要进行进一步的检查（如活检），额外的检查也存在风险。
以下的结直肠癌筛查有风险：
结肠镜检查
结肠镜检查很少会出现严重的并发症，但有时会导致结肠内膜撕裂和出血。这些并发症常发生于活检或息肉切除，可能会很严重并需要住院治疗。
镇静剂用于减少镜检过程中的不适感。镇静剂可能会导致心肺问题，例如心律不齐，心力衰竭或呼吸困难。
乙状结肠镜检查
乙状结肠镜检查的并发症少于结肠镜检查。尽管也会发生结肠内膜撕裂和出血，但发生率低于结肠镜检查。乙状结肠镜检查通常不需要服用镇静剂，可降低出现并发症的风险。
虚拟结肠镜检查
与结肠镜或乙状结肠镜检查相比，虚拟结肠镜检查对身体伤害的风险最小。在虚拟结肠镜检查中暴露于x射线的危害尚不清楚。除结肠以外，虚拟结肠镜检查通常会发现其他器官存在的问题，包括肾脏、胸部、肝脏、卵巢、脾脏和胰腺。这些发现会导致更多的检查，如结肠镜检查，而这些检查可能无法改善患者的健康。
粪便潜血试验（FOBT）或粪便DNA检测
即使没有发现癌症，FOBT或DNA粪便的检测结果也可能是异常的。阳性结果可能需要进行更多检查，包括结肠镜检查。
Risks of Colorectal Cancer Screening
Screening tests have risks.
Decisions about screening tests can be difficult. Not all screening tests are helpful and most have risks. Different screening tests have different risks or harms. Screening tests may cause anxiety when you are thinking about or getting ready for the test or when there is a positive test result. 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.
Talk to your doctor about your risk for colorectal cancer and the need for screening tests.
False-negative test results can occur.
Screening test results may appear to be normal even though colorectal 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.
The following colorectal cancer screening tests have risks:
Colonoscopy
Serious problems caused by colonoscopy are rare, but can include tears in the lining of the colon and bleeding. These problems can be serious and need to be treated in a hospital. Tearing of the lining of the colon and bleeding occur more often when a biopsy or polypectomy is done.
Sedation is used to decrease the discomfort from the procedure. Sedation may cause heart and lung problems, such as irregular heartbeat, heart attack, or trouble breathing.
Sigmoidoscopy
There are fewer complications with a sigmoidoscopy than with a colonoscopy. Although tears in the lining of the colon and bleeding can occur, they are less common than with a colonoscopy. There is usually no sedation with sigmoidoscopy, lowering the risk of complications.
Virtual colonoscopy
Virtual colonoscopy has fewer possible physical harms than either colonoscopy or sigmoidoscopy. The harms of being exposed to radiation from x-rays used in virtual colonoscopy are not known. Virtual colonoscopy often finds problems with organs other than the colon, including the kidneys, chest, liver, ovaries, spleen, and pancreas. Some of these findings lead to more testing, such as colonoscopy, that may not improve the patient's health.
Fecal occult blood test (FOBT) or DNA stool test
The results of an FOBT or DNA stool test may appear to be abnormal even though no cancer is found. A positive test result may lead to more testing, including colonoscopy.
About This PDQ Summary
About PDQ
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.
Purpose of This Summary
This PDQ cancer information summary has current information about colorectal 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.
Reviewers and Updates
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.
Clinical Trial Information
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).
Permission to Use This Summary
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 Colorectal 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.
Disclaimer
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.
Contact Us
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.
About This PDQ Summary
About PDQ
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.
Purpose of This Summary
This PDQ cancer information summary has current information about colorectal 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.
Reviewers and Updates
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.
Clinical Trial Information
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).
Permission to Use This Summary
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 Colorectal 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.
Disclaimer
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.
Contact Us
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.