Lung cancer screening refers to a cancer screening strategy used to identify early lung cancer before they cause symptoms, at a point where they are more likely to be curable. More than 224,000 new cases of lung cancer are expected by 2016 with an estimated 155,000 deaths by 2017. 57% are diagnosed at an advanced stage (III and IV) where survival is poor. Screening studies discussed potential differences in some parameters between the study subjects with and without screening. Because there is a much higher likelihood of long-term survival after treatment at localization (55%) than in advanced stage (5%), the specific reason for lung cancer screening is to diagnose the disease at stage I. The study parameters include specific mortality population mortality, all causes of death, long-term survival after cancer diagnosis, screening risk and cost effectiveness. Screening studies for lung cancer are only performed on high-risk populations in the US, such as smokers and workers with occupational exposure to certain substances. The results of a large randomized study recently prompted a large number of professional organizations and government agencies in the US to now recommend lung cancer screening in selected populations.
CT screening has been associated with a high false positive test rate that can lead to unnecessary treatment. For every correct positive scan, there are 19 false positive scans. When screening is done in the context of a diagnostic test process, false positives have been reduced to about 12%. Other concerns include radiation exposure and testing costs as well as follow-up of tests. Research has not found two other available clinical trials - sputum cytology or chest radiography (CXR) - to reduce the overall number of people who die from lung cancer.
Screening studies for lung cancer are only performed on high-risk populations in the US, such as smokers and workers with occupational exposure to certain substances. In 2010 recommendations by medical authorities turned to support lung cancer screening, which tends to become more widely available in developed countries. Currently, some professional organizations and the United States Prevention Task Force (USPSTF) and Medicare and Medicaid Service Center (CMS) agree and support low-dose computerized tomographic screening for individuals at high risk of lung cancer.
Video Lung cancer screening
Scanning Risk
Research has found that regular early screening with two other available clinical trials - sputum cytology and thoracic radiography (CXR) - has no overall benefit. There is evidence to suggest that regular screening of high-risk smokers and former smokers can reduce mortality in this particular group of people. Further research is needed to determine the relative risks and benefits for the general population and those who have a low risk of lung cancer.
CT screening has been associated with a high false positive test rate that can lead to unnecessary treatment. For every correct positive scan, there are 19 false positive scans. Other concerns include radiation exposure and testing costs as well as follow-up of tests. Fake collateral from false negative findings, overdiagnosis, short-term anxiety/distress, and increased incidental findings are another risk. It is estimated that radiation exposure from repeated screening studies may induce cancer formation in a small percentage of the screened subject, so this risk should be reduced by the relatively high prevalence of lung cancer in the screened population.
Maps Lung cancer screening
Guidelines
The National Lung Screening Trial found that screening of people aged between 55 and 74 years old who had smoked, and had quit smoking no more than 15 before being screened, allowed timely intervention of up to 16% fewer people died of lung cancer, compared with unfiltered people.
Based on this study, the US Prevention Services Task Force recommends annual screening for lung cancer with low-dose computed tomography in adults aged 55 to 80 years who have a smoking history of 30 packs per year and is currently smoking or has stopped within the past 15 years.. Screening should be discontinued after a person has not smoked for 15 years or develop a health problem that substantially limits life expectancy or ability or willingness to undergo lung curative surgery.
This form of screening reduces the likelihood of death from lung cancer by an absolute 0.3% (relative 20%).
The definition of those who are considered at high risk to benefit from filtering varies according to different guidelines. Initially high risk includes people aged 55-74 years who have smoked a pack of cigarettes every day for 30 years including the time in the last 15 years. The US Preventation Service Task Force (USPSTF) and the Center for Medicare and Medicaid Services (CMS) categorization are for those aged 55-80 and 55-77 respectively who smoked an average pack of cigarettes daily for 30 years and currently smokers or have quit in the last 15 years.
The National Comprehensive Cancer Network (NCCN) guidelines recommend screening in the second risk category that includes individuals over 50 who have smoked over 20 pack years who have a second risk factor and do not set an upper age limit at which screening should be stopped.
History
The study has explored various screening methods, including breath tests and blood tests to detect lung cancer. Despite scientific evidence that lung cancer is detectable with high sensitivity and over 90% specificity in human breath, there are no clinically validated screening tests to be useful for screening.
Medical imaging has been studied extensively. Lung cancer screening program using plain chest x-rays (CXR) and sputum analysis programs have not been found to be effective in reducing deaths from lung cancer, except in high-risk smokers. The cost-benefit analysis versus the potential hazards of screening people with various lung cancer risks has not been fully investigated.
The Mayo Lung Project followed more than 9000 male smokers over 45 who smoked one or more packs a day from 1971 to 1986 and compared the CXR intensive and sputum screening every three times per year compared to less frequent annual screening. The results showed that more frequent screening resulted in higher levels of resectability (early stage detection), but no difference in mortality from lung cancer. CXR screening was found to detect 6 times as many new cancers as a sputum test.
In 1996 results were published from the study of about 6,800 subjects aired in Japan; 67% to 73% of CT lung cancers were missed by chest x-ray, the same tests used in the comparison group of randomized controlled trials of lung cancer screening.
The National Lung Screening Test is a US-based clinical trial that recruits study participants between 2002-2004. It is sponsored by the National Cancer Institute and conducted by the American College of Radiology Imaging Network and Lung Screening Research Group. The main study in this experiment was to compare the efficacy of low-dose helical computed tomography (CT screening) and chest X-ray standard as a lung cancer screening method.
CT screening results in more than 31,000 high-risk patients were published in late 2006 at the New England Journal of Medicine. In this study, 85% of the 484 lung cancers detected were stage I and thus highly treatable. Historically, such stage I patients would have an expected 10-year life expectancy of 88%. Critics of the I-ELCAP study showed no patient randomization (all CT scans were accepted and no comparison group received chest x-ray) and the patient did not actually follow 10 years post-detection (median follow-up was 40 months).
In contrast, a March 2007 study at the Journal of the American Medical Association (JAMA) found no death benefit from CT-based lung cancer screening. 3,200 current or former smokers are screened for 4 years and offer 3 or 4 CT scans. The diagnosis of lung cancer was 3 times higher, and surgery was 10 times higher, as predicted by the model, but there was no significant difference between the observed number and the estimated number of advanced cancers or deaths. Additional controversy arose after the 2008 New York Times reported that the 2006 CT-scan study in the New England Journal of Medicine was funded indirectly by the parent company of Liggett Group, a company tobacco.
In 2011, the National Lung Screen found that CT screening offered benefits compared to other tests. The study is recognized to provide supporting evidence for using CR screening for screening for lung cancer and to encourage others to reflect on the benefits and disadvantages of other types of screening. Research has not shown that two other tests available - sputum cytology or chest radiography (CXR) - have any benefit.
This experiment led to recommendations in the United States that CT screening is used in people at high risk for developing lung cancer in an attempt to detect previous cancers and reduce mortality.
In December 2013, the US Preventive Services Task Force (USPSTF) amended its long-term recommendation that there was insufficient evidence to recommend or reject screening for lung cancer as follows: "USPSTF recommends annual screening for low-dose lung cancer computed tomography on adults aged 55 to 80 years who have a smoking history of 30 packs per year and are currently smoking or have quit in the past 15 years.The recommendation is used by the Research and Quality Health Agency (AHRQ) to generate patient and physician resources to support decision making based on information for lung cancer screening Screening should be discontinued after a person has not smoked for 15 years or develop a health problem that substantially limits life expectancy or ability or willingness to undergo curative lung surgery Other US guideline recommendations are very similar, but with cut- off on age 74. The UK's National Health Service in 2014 re-examined evidence for screening.
Development of the guide
Clinical practice guidelines previously issued by the American College of Chest Physicians in 2007 were recommended not to conduct routine checks for lung cancer due to a lack of evidence that the examination was effective. The latest ACCP guidelines take into account the findings of the National Screening Trial and states: "For smokers and former smokers aged 55-74 and who smoked for 30 pack years or more and continued smoking or quitting in the last 15 years, that annual screening with low-dose CT (LDCT) should be offered through annual screening with CXR or without screening, but only in settings that can provide comprehensive care provided to National Screening Test participants (Class 2B)) ".
After the National Cancer Institute National Lung Screening Trial, the guidelines were released in early 2012 by the National Comprehensive Cancer Network, an alliance of twenty-one cancer centers in the United States. Their consensus guidelines, updated annually, support screening as a process, not a single test, and discuss the risks and benefits of screening at high risk individuals in a comprehensive multidisciplinary program. Screening is only recommended for individuals who are defined as high risk that meet certain criteria. More details can be found in their patient guidelines. While lung cancer screening programs have been supported by the NCCN, the International Association for the Study of Lung Cancer (IASLC), the American Cancer Society, the American Society of Clinical Oncology (ASCO), and other organizations, the cost of screening may not be covered by health insurance policies, the eligibility criteria determined by the Medicare and Medicaid Service Centers (CMS) are met.
Beginning 2017 the use of lung cancer screening in the US after Medicare agreed to pay for screening and after published guidelines were low, with the most uptake in the Midwest. In 2017, the task force publishes review reviews and recommendations to advance implementation.
References
This article incorporates public domain material from the United States Department of Health and Public Service documents: Ã, "Body of Research and Quality of Health, US Prevention Services Task Force" . Retrieved 2017-06-19 .
Source of the article : Wikipedia
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