PREVENTION OF PRIMARY DISEASE

Smoking Cessation Lung cancer initially had a humble
beginning, with early case reports remarking on the rarity of the
disease. Only after the tremendous increase in smoking worldwide
following World War I did lung cancer begin to achieve
its current level of notoriety. 9 Since the initial linkage between
tobacco smoke and lung cancer in 1950, 10,11 this risk factor
has been extensively investigated. Smoking currently accounts
for 87% of lung cancer deaths, 12 and thus smoking cessation
represents the most broadly applicable approach to primary
prevention. Initiatives in the United States have only recently
begun to result in a reduction in lung cancer mortality. 3 One
reason for this sluggish response is that a former smoker’s risk
of lung cancer never returns to that of a nonsmoker. 4,5 In fact,
at present, about 50% of cancer diagnoses are made among
former smokers. 5,9 New medications may improve the success
of individual smoking cessation attempts, but this rate remains
below 10% over the long term with heavy smokers. Despite
these limitations, tobacco control and smoking cessation remain
key components of the primary prevention of lung cancer,
with the long-term potential to banish this lethal disease
back into obscurity. Lung cancer risk increases with duration
of smoking. However, the increasing risk of lung cancer stops
rising with smoking cessation.
Obstacles to Population-Level Smoking Cessation
Initiatives Several obstacles stand in the way of smoking
cessation initiatives. Smoking prevalence remains high.
Worldwide smoking prevalence is 47% among men and 12%
among women. 9 An estimated 45 million Americans are current
smokers, with a like number of former smokers. 13 Adolescent
smoking is also a persistent and serious problem. Tobacco addiction
is not typically considered a pediatric disease, but data
suggest that most adult smokers become addicted between age
13 and 17. 9 With this background, the fact that about 30% of
high school students report the use of some form of tobacco
product within the previous month 14 takes on greater significance.
Secondhand smoke expands the reach of lung cancer
to nonsmokers. About 126 million nonsmoking Americans
are exposed to secondhand smoke in the workplace, home,
vehicles, or public places, 15 and about 3000 nonsmokers die
of lung cancer as a result each year. 16 Despite legally imposed
limitations, the tobacco industry continues to advance its interests,
with promotional expenditures exceeding tobacco control
spending by a ratio of 23 to 1 in 2003. Declines in smoking
cessation rates among adults and high school students appear
to have stalled, 17 likely as a consequence of increased industry
marketing expenditures, decreased funding for comprehensive
tobacco control programs, and lack of a significant increase in
tobacco prices. 18 While rates of smoking prevalence in other
developed countries have largely mirrored the decline observed
in the United States, increased marketing in the face of limited
financial resources has resulted in increased tobacco consumption
in developing countries. 19
Recommendations for Smoking Cessation Initiatives
The U.S. Surgeon General’s report specified the goals of preventing
tobacco use initiation among the young, promoting
quitting, and eliminating nonsmokers’ exposure to secondhand
smoke. 1 A subcommittee of the U.S. Interagency Committee
on Smoking and Health (ICSH), with public input, developed
a national action plan consisting of ten recommendations for
smoking cessation. 20 The Centers for Disease Control and
Prevention provided recommendations for the essential components
of comprehensive tobacco control programs. 21 The
World Health Organization recently published its recommendations
to curb the global smoking epidemic. 19 These recommendations
are summarized in Table 15.1, most of which will
be discussed in more detail.
Youth Access Laws Laws aimed at restricting children
and adolescents from purchasing tobacco products have not
been very successful. Some studies suggest that such laws have
no impact on adolescent smoking, 22,23 whereas others demonstrate
a decrease in the number of adolescents who experiment
with smoking. 24 Regardless, most smokers become addicted
before they can purchase cigarettes legally. 25 Lack of enforcement
may largely explain the lack of efficacy of this approach.
Smoke-Free Laws As of January 2008, 26 states, encompassing
53% of Americans, had enacted or implemented legislation
that prohibits smoking in the workplace, restaurants, or
bars. 26 However, only 5% of the global population is protected
by smoke-free laws. 19 Comprehensive public smoking bans are
the most effective, with exposure to secondhand smoke being
reduced from 46% in countries without regulations to 12% in
those with extensive restrictions, but only to 35% in countries
with limited restrictions. 27 Additional benefits of such programs
are a reduction in smoking prevalence and tobacco consumption
by smokers, as well as lower rates of youth smoking specifically. 15
A metaanalysis reported a 3.8% reduction in smoking prevalence
and decrease by 3.1 cigarettes per day per continuing smoker.
These results equate to a 29% reduction in cigarette consumption
per employee. Public smoking bans decrease youth smoking
prevalence, and school bans decrease daily consumption. 22
Greece has the highest proportion (45%) of adult smokers
in Europe. Many European countries have now adopted
public smoking bans. Ireland was the first European country to
implement a comprehensive ban on smoking in public places in
March 2004. Norway followed soon after, but allowed a smokers’
corner in workplaces. Italy banned workplace smoking in
January 2005 and Naples and Verona have made smoking illegal
in public parks. Belgium allows smoking in cafes and bars
if they have ventilation installed and are at least 50 sq m (538
sq ft) in area. In France, a law forbidding smoking in public
places was extended to bars, cafes, and hotels in January 2008,
with fines up to 450 euros (£332; $662). Eight German states,
including Berlin, have also ushered banned smoking in 2008
declaring their pubs and restaurants smoke free. Almost a third
of Germans smoke and the authorities in Berlin decided not to
enforce the restrictions actively for the first 6 months.
In summary, highly restrictive smoke free laws have a tremendous
potential to reduce smoking prevalence and tobacco
consumption at the population level, but are underutilized
even in developed countries.
Methods to Improve Individual Smoking Cessation
Rates The rate of smoking cessation without any intervention
is about 1% per year. This value varies by population, however,
with this low rate being typical of smokers seen in a general medicine
clinic. Higher baseline rates can be expected of individuals
presenting to a smoking cessation clinic or following hospitalization
for a smoking-related illness, such as myocardial infarction.
Despite this discouraging figure, many smokers are motivated to
make cessation attempts, with about 42% reporting at least one
attempt in the prior 1 year. 14,28 A significant opportunity exists
for healthcare providers to intervene, as 70% of smokers visit
their physicians annually. Physician counseling for only 2 to 3
minutes increases the rate of smoking cessation to 3%, making
this intervention more cost-effective than treatment of dyslipidemia
or mild-to-moderate hypertension. Tobacco quit lines are
another means of providing counseling. Smokers are four times
more likely to utilize a quit line than to seek help in person,
and success rates of up to 20% can be achieved. 20 Quit lines are
toll free and thus expand the access of underserved populations
to smoking cessation resources. Telephone counseling in more
effective than mailed self-help materials, 29 and personalized correspondence
is superior to standardized letters. 22 Pharmacologic
therapy, in the form of nicotine replacement, bupropion, or
varenicline, also improves long-term smoking cessation rates. 30
Although counseling and pharmacotherapy are cost-effective
when compared to other covered services, 20 insurance coverage
of smoking cessation treatments varies. Only 20% of employersponsored
plans provide at least some coverage, 31–34 Medicaid
provides no coverage in 14 states, 31 and Medicare only covers
treatment of individuals with smoking-related diseases. 35
Clearly, support for at least some of these interventions is a realistic
goal for any country in the world.
Antismoking Media Campaigns Many smokers are not
aware of the negative health consequences of smoking. Media
campaigns offer a mechanism of providing education and countering
specific misconceptions about smoking. Most recently,
these campaigns have successfully targeted child and adolescent
smoking. A media campaign coupled with a school-based
program resulted in a decrease in reported smoking and weekly
smoking in children in grades 4 through 6. Twelve- to thirteenyear-
old individuals who reported seeing antismoking advertisements
(ads) had half the chance of becoming established
smokers as those who did not see the ads. 24 A nationwide antismoking
media campaign was credited with 22% of the decline
in youth smoking between 1990 and 2002. 36 Additional
factors in this decline were restrictions on public smoking and
an increase in the price of cigarettes. 37–39 Securing the financial
resources necessary to conduct large-scale antismoking media
campaigns is a challenge, made more serious by expanded tobacco
industry marketing in developing countries, but it can
be offset or overcome in the following way.
Excise Taxes Imposing a tax on tobacco products has the potential
to accomplish several goals. Currently, taxes are levied by
state and local governments in the United States, resulting in striking
disparities in the price of tobacco products across the country.
Not surprisingly, most smokers obtain cigarettes in geographic locations
with the lowest cost or employ other high-price avoidance
strategies. 40 This practice is associated with a lower probability of
making a cessation attempt and possibly a lower quit rate. 41 A
federal tax on tobacco products would have the effect of equalizing
their price, thereby preventing this evasion tactic. Imposing
such a tax would have at least two other potential benefits. A 10%
increase in cigarette price reduces consumption by 3% to 5%. 42
This effect is more pronounced among economically disadvantaged
individuals, including children and adolescents. 20 Although
smoking cessation is the preferred outcome, a reduction in consumption
may decrease the risk of lung cancer. A 50% reduction
in consumption among those smoking 15 or more cigarettes
per day is associated with a 27% reduction in lung cancer risk. 43
The second direct benefit is the revenue that these taxes generate,
which is generally sufficient to fund other components of a comprehensive
tobacco control program. Tobacco companies spend
about $11 billion per year to offset these taxes. 44
Outcomes of Comprehensive Tobacco Control
Programs The fundamental measures employed by comprehensive
tobacco control programs are excise taxes, antismoking
media campaigns, and smoke-free laws. Results from
two programs, in Massachusetts and New York, have been published.
The Massachusetts Tobacco Control Program (MTCP)
reduced consumption from 547 million packs to 280 million
from 1992 to 2004, a decline of 4% per year. Even after adjustment
for unequal increases in excise taxes, this decrease
exceeded that of states that did not have control programs in
place over the study period. Smoking prevalence decreased
from 23.5% to 19.4% over 1990 to 1999. High school smoking
prevalence decreased from 30.2% to 20.9% from 1993 to
2003. Smoking bans decreased exposure to smoking in the
workplace from 44% to 15% from 1993 to 2001, in the home
from 28% to 16%, and in restaurants from 64% to 37% from
1993 to 2002. 24 New York City’s program incorporated a tax
increase, workplace smoking ban, and free nicotine patch program.
These efforts resulted in an 11% reduction, from 21.6%
to 19.2%, in smoking prevalence over 1 year, equating to
140,000 individuals who quit smoking. Forty-five percent of
smokers reported cutting down, thinking about quitting, trying
to quit, or quitting as a result of these initiatives. Forty-six
percent of individuals reported less exposure to secondhand
smoke following introduction of the program. The proportion
of nonsmokers reporting secondhand smoke exposure at
home decreased 29%, from 8.5% to 6%, equating to 105,000
fewer nonsmokers exposed. The proportion reporting workplace
exposure decreased 18%, from 8.9% to 7.3%, a reduction
of 67,000 nonsmokers exposed. Not surprisingly in a
program implemented within a relatively narrow geographic
region, purchases through alternative channels increased 89%,
but nevertheless yielded a net reduction in consumption of
15%. 45 A statewide ban on public smoking decreased exposure
to secondhand smoke from 19.8% to 3.1% in restaurants
and from 52.4% to 13.4% in bars in New York. Salivary cotinine
levels, a marker of smoke exposure, decreased from 0.078
ng/mL to 0.041 ng/mL among nonsmokers. 46 Overall findings
from comprehensive tobacco control programs suggest
that warning labels and advertising restrictions are less effective
than increased taxes, smoking bans, and counteradvertising.
22 Concordant with the results observed in Massachusetts,
per capita cigarette purchases declined 16% to 20% in states
implementing tax-supported antismoking programs. 22
Impact on Lung Cancer Mortality Smoking prevalence
fell from 42.3% to 23.2% in the United States between 1965
and 1997, but lung cancer incidence increased 230% between
1965 and 1999. 9 This highlights the fact that lung cancer risk
reduction is both delayed and incomplete following smoking
cessation. The cumulative incidence of lung cancer through age
75 is about 16% for lifelong smokers, compared to less than
1% for lifelong nonsmokers. Smoking cessation at age 30, 40,
or 50 years results in cumulative incidence rates of about 2%,
3%, and 6%, respectively. 47 These data indicate that a significant
burden of lung cancer risk, and thus lung cancer mortality,
can be eliminated by early smoking cessation, but that the risk
never decreases to the level of a lifelong nonsmoker. This reality
suggests that smoking cessation remains a critical prevention
strategy; however, in an evolving situation where the number
of former smokers whose significant lung cancer risk never normalizes,
additional public health measures are required. 48
Population-Based Screening Published lung cancer
screening trials have generally involved current and former
smokers. Family history may be an additional factor to consider
when selecting the population to screen. A family history of
lung cancer is an independent risk factor for lung cancer. The
diagnosis of squamous cell carcinoma in a first-degree relative
appears to confer the greatest risk. 49 The risk of lung cancer in
secondhand smoke–exposed individuals is measurable but significantly
lower than in smokers. This means the potential cost
benefit ratio will not be as favorable as for the smoking cohort
and no prospective information addresses this circumstance as
yet. Two large ongoing trials are accruing to address this issue
(Flight Attendants Medical Research Institute, [FAMRI] and the
International Early Lung Cancer Action Project [I-ELCAP]).
Other risk factors for lung cancer include radon, asbestosis, certain
metals (chromium, cadmium, arsenic), some organic chemicals,
radiation, air pollution, tuberculosis, and genetic factors. 1
Other approaches to early lung cancer detection have been
reported such as with techniques to evaluate tobacco-exposed
bronchial epithelial cells recovered in the sputum of smokers.
An antibody against heterogeneous nuclear ribonucleoprotein
A2/B1 has demonstrated high sensitivity and specificity for the
detection of lung cancer in high-risk individuals. 50–52 However,
scaling such a test to achieve the requisite accuracy at affordable
cost is a profound challenge given the comparable cost and
availability of spiral CT screening.