The most important risk factor for lung cancer is smoking.2,3 Smoking is estimated to account for about 90% of all lung cancer cases,2 with a relative risk of lung cancer approximately 20-fold higher in smokers than in nonsmokers.3 Increasing age is also a risk factor for lung cancer. The median age of diagnosis of lung cancer is 70 years.4,5
The US Preventive Services Task Force (USPSTF) concludes with moderate certainty that annual screening for lung cancer with LDCT has a moderate net benefit in persons at high risk of lung cancer based on age, total cumulative exposure to tobacco smoke, and years since quitting smoking. The moderate net benefit of screening depends on limiting screening to persons at high risk, the accuracy of image interpretation being similar to or better than that found in clinical trials, and the resolution of most false-positive results with serial imaging rather than invasive procedures.
Smoking and older age are the 2 most important risk factors for lung cancer.3-5 The risk of lung cancer in persons who smoke increases with cumulative quantity and duration of smoking and with age but decreases with increasing time since quitting for persons who formerly smoked.3 The USPSTF considers adults aged 50 to 80 years who have a 20 pack-year smoking history and currently smoke or have quit within the past 15 years to be at high risk and recommends screening for lung cancer with annual LDCT in this population.
As noted above, the USPSTF recommends annual screening for lung cancer with LDCT in adults aged 50 to 80 years who have at least a 20 pack-year smoking history. Screening should be discontinued once a person has not smoked for 15 years.
All persons enrolled in a screening program who are current smokers should receive smoking cessation interventions. To be consistent with the USPSTF recommendation on counseling and interventions to prevent tobacco use and tobacco-caused disease,19 persons referred for lung cancer screening through primary care should receive these interventions concurrent with referral. Because many persons may enter screening through pathways besides referral from primary care, the USPSTF encourages incorporating such interventions into all screening programs.
Prevention of initiation of smoking and smoking cessation for those who smoke are the most important interventions to prevent lung cancer. The USPSTF has made recommendations on interventions to prevent the initiation of tobacco use in children and adolescents22 and on the use of pharmacotherapy and counseling for tobacco cessation.19
This recommendation replaces the 2013 USPSTF recommendation on screening for lung cancer. In 2013 the USPSTF recommended annual screening for lung cancer with LDCT in adults aged 55 to 80 years who have a 30 pack-year smoking history and currently smoke or have quit within the past 15 years (abbreviated as A-55-80-30-15).23 For this updated recommendation, the USPSTF has changed the age range and pack-year eligibility criteria and recommends annual screening for lung cancer with LDCT in adults aged 50 to 80 years who have a 20 pack-year smoking history and currently smoke or have quit within the past 15 years (A-50-80-20-15). Abbreviations for screening recommendations are expanded in the Box.
As in the 2013 recommendation, the USPSTF recommends that screening should be discontinued once a person has not smoked for 15 years or develops a health problem that substantially limits life expectancy or the ability or willingness to have curative lung surgery.
The NLST, the largest RCT to date (n = 53,454), enrolled participants aged 55 to 74 years at the time of randomization who had a tobacco use history of at least 30 pack-years and were current smokers or had quit within the past 15 years. The mean pack-year smoking history in NLST participants was 56 pack-years.9 The NELSON trial (n = 15,792) enrolled participants aged 50 to 74 years who had a tobacco use history of at least 15 cigarettes a day (three-fourths of a pack per day) for more than 25 years or 10 cigarettes a day (one-half of a pack per day) for more than 30 years and were current smokers or had quit within the past 10 years. The median pack-year smoking history in NELSON trial participants was 38 pack-years.11
Relative to the 2013 USPSTF screening program (A-55-80-30-15), CISNET modeling analyses suggest that annually screening persons aged 50 to 80 years who have at least a 20 pack-year smoking history and currently smoke or have quit within the past 15 years (A-50-80-20-15) would be associated with lung cancer mortality reduced by 13.0% vs 9.8%, with avoiding 503 vs 381 lung cancer deaths, and with 6918 life-years gained vs 4882 life-years gained per 100,000 persons in the population aged 45 to 90 years over a lifetime of screening.14 Thus, this screening program would be associated with important reductions in lung cancer deaths and increases in life-years gained compared with the previous recommendation and is supported by new trial data and the CISNET modeling studies.
A draft version of this recommendation statement was posted for public comment on the USPSTF website from July 7, 2020, to August 3, 2020. Most comments generally agreed with the draft recommendation, although some requested broadening the eligibility criteria for lung cancer screening and others mentioned that additional risk factors for lung cancer other than smoking exist or that lung cancer can occur in persons who never smoked. In response, the USPSTF acknowledges that there are risk factors for lung cancer other than smoking; however, current evidence does not support the incorporation of these risk factors as determinants of eligibility for lung cancer screening. The USPSTF also acknowledges that lung cancer can occur in persons who never smoked or among persons who currently smoke or formerly smoked who do not meet screening eligibility criteria. Nevertheless, smoking is the major risk factor for lung cancer, all trials of screening for lung cancer have been conducted among persons who smoke or were former smokers, and trial and modeling data support the current USPSTF recommendation as offering a reasonable balance of benefits and harms.
The American Cancer Society recommends annual lung cancer screening with LDCT for persons aged 55 to 74 years who are in fairly good health, have at least a 30 pack-year smoking history, and currently smoke or have quit within the past 15 years. It also recommends smoking cessation counseling for current smokers, shared decision-making about lung cancer screening, and that screening be conducted in a high-volume, high-quality lung cancer screening and treatment center.44
The American College of Chest Physicians suggests that annual screening with LDCT should be offered to asymptomatic smokers and former smokers aged 55 to 77 years who have smoked 30 pack-years or more and either continue to smoke or have quit within the past 15 years. It also recommends that screening not be performed for individuals with comorbidities that adversely influence their ability to tolerate the evaluation of screen-detected findings or tolerate treatment of an early-stage screen-detected lung cancer or that substantially limit their life expectancy.45
The National Comprehensive Cancer Network recommends annual screening for lung cancer with LDCT in persons aged 55 to 77 years who have at least a 30 pack-year smoking history and currently smoke or have quit within the past 15 years or in persons 50 years or older who have at least a 20 pack-year smoking history and have at least 1 additional risk factor for lung cancer.46
In 2013, The US Preventive Services Task Force (USPSTF) recommended annual screening for lung cancer with low-dose computed tomography (LDCT) for adults aged 55 to 80 years who have a 30 pack-year smoking history and currently smoke or have quit within the past 15 years (abbreviated as A-55-80-30-15).23
Importance: Tobacco use is the leading preventable cause of disease, disability, and death in the US. In 2014, it was estimated that 480 000 deaths annually are attributed to cigarette smoking, including second hand smoke exposure. Smoking during pregnancy can increase the risk of numerous adverse pregnancy outcomes (eg, miscarriage and congenital anomalies) and complications in the offspring (including sudden infant death syndrome and impaired lung function in childhood). In 2019, an estimated 50.6 million US adults (20.8% of the adult population) used tobacco; 14.0% of the US adult population currently smoked cigarettes and 4.5% of the adult population used electronic cigarettes (e-cigarettes). Among pregnant US women who gave birth in 2016, 7.2% reported smoking cigarettes while pregnant.
Evidence assessment: The USPSTF concludes with high certainty that the net benefit of behavioral interventions and US Food and Drug Associated (FDA)-approved pharmacotherapy for tobacco smoking cessation, alone or combined, in nonpregnant adults who smoke is substantial. The USPSTF concludes with high certainty that the net benefit of behavioral interventions for tobacco smoking cessation on perinatal outcomes and smoking cessation in pregnant persons is substantial. The USPSTF concludes that the evidence on pharmacotherapy interventions for tobacco smoking cessation in pregnant persons is insufficient because few studies are available, and the balance of benefits and harms cannot be determined. The USPSTF concludes that the evidence on the use of e-cigarettes for tobacco smoking cessation in adults, including pregnant persons, is insufficient, and the balance of benefits and harms cannot be determined. The USPSTF has identified the lack of well-designed, randomized clinical trials on e-cigarettes that report smoking abstinence or adverse events as a critical gap in the evidence.
However I'm having a hard time getting the smoke to billow outwards from the face; it seems to only flow in a straight column whether using temperature difference or any of the wind settings. Should I crank up the strength of the turbulence field, or do you have some other ideas of how I might achieve this, another sort of force field maybe?
aa06259810