An Update About Tobacco and Cancer: What Clinicians Should Know
- First Online:
- Cite this article as:
- Schroeder, S.A. J Canc Educ (2012) 27: 5. doi:10.1007/s13187-012-0327-2
- 153 Views
Anyone concerned about cancer should know that enemy number one is tobacco use, which accounts for an estimated 30% of all cancers . Yet, because so many smokers are unable to quit, and because cancer specialists generally see patients when the damage from smoking has already occurred, there may be a tendency to view smoking as a “done deal” for which little can be accomplished. This brief review updates information on smoking, the remarkable progress that has occurred regarding smoking prevalence and cessation, and the challenges we face if we are to reduce the huge disease burden from tobacco use.
What We Do Know
A large body of information has accumulated about the harms of tobacco use (especially smoking), the epidemiology of smoking, and policies to reduce smoking.
Tobacco and Illness
Despite recent declines in smoking prevalence, tobacco use still kills about 450,000 people annually in the United States, and 5 million worldwide . Of those deaths in the U.S., about 50,000 are attributed to second-hand smoke exposure. Furthermore, about 8.5 million smokers are disabled with illnesses such as chronic obstructive pulmonary disease. What are the causes of tobacco-related deaths? The largest categories are lung cancer (about 30%), other cancers (9%), cardiovascular diseases (35%) , and pulmonary diseases (25%) .
Health consequences of smoking
○ Acute myeloid leukemia
○ Bladder and kidney
○ Oral cavity and pharyngeal
○ Prostate (incidence and survival)
○ Acute (e.g., pneumonia
○ Chronic (e.g., COPD)
○ Abdominal aortic aneurysm
○ Coronary heart disease
○ Cerebrovascular disease
○ Peripheral arterial disease
○ Type 2 diabetes mellitus
○ Reduced fertility in women
○ Poor pregnancy outcomes (e.g., low birth weight, preterm delivery)
○ Infant mortality, childhood obesity
Other effects: cataract, osteoporosis, periodontitis, poor surgical outcomes, Alzheimers
Health consequences of second-hand smoke (Increased odds ratios): There is no safe level of second-hand smoke
Causal associations with second-hand smoke
○ Low birthweight
○ Sudden infant death syndrome (SIDS)
○ Pre-term delivery
○ Childhood depression
○ Asthma induction and exacerbation
○ Eye and nasal irritation
○ Bronchitis, pneumonia, otitis media in children
○ Decreased hearing in teens
○ Lung cancer
○ Nasal sinus cancer
○ Breast cancer (younger, premenopausal women
○ Heart disease mortality
○ Acute and chronic coronary heart disease morbidity
○ Altered vascular properties
The Epidemiology of Tobacco Use
Smoking exerts a particularly heavy toll on those with behavioral health problems. It is estimated that 44% of all cigarettes consumed in the U.S. are by those with mental illness and substance abuse disorders. This is because this population has high rates of smoking and also smokes more daily cigarettes. Not surprisingly, such heavy smoking exerts a high medical toll. Recent data have shown that those with serious mental illness die, on average, 25 years earlier than the general population, and that most of those deaths are from illnesses that are exacerbated by smoking, such as heart disease, lung cancer, and diabetes .
Policies to Reduce Tobacco Use
Tobacco use is decreased by the adoption of proven tobacco-control policies. The two most important of these are the passage and enforcement of clean indoor air laws and the taxation of tobacco products. Other policies are the use of counseling and medications to help smokers quit, the use of media to counter-market tobacco use by deglamorizing it and highlighting its health perils, and the insertion in cigarette packages of graphic warning labels and photos (here the evidence is from other countries). Although the decline in smoking levels is rightly heralded as one of the major public health triumphs of the past half century, there is still a major imbalance between the resources spent by the tobacco industry and the efforts of public health advocates and government agencies to protect against tobacco use . Notably, despite the huge health toll from tobacco, there are very few popular advocacy campaigns, in contrast to such health conditions as breast cancer, autism, or Parkinson’s Disease.
What We Don’t Know
The Meaning of Recent Trends
Smoking cessation levels are a function of the number of smokers attempting to quit and the proportion who are able to quit. Remarkably, despite the increasing stigmatization of smoking and the expanding number of tools to aid cessation (e.g., counseling, 7 FDA-approved drugs, and toll-free telephone quitlines), there has been no change during the past decade in either the proportion of quit attempts (just below 50% of all smokers) or successful quits (about 5%). How to accelerate quitting is a major challenge for clinicians and public health workers .
Another trend is the fact that within the smoking population there are now fewer heavy smokers and more light smokers. For example, in 1965 23% of the population smoked more than a pack a day; by 2007 that proportion had declined to 7% . Put another way, in 1990 only 45% of California smokers were light smokers (less than 15 cigarettes per day) or nondaily smokers; by 2005 that proportion had increased to 67%. Since most of the literature on smoking cessation medications is based on more intense smokers, the extent to which light and nondaily smokers can benefit from these treatments is unclear. Although the 2008 Updated Guideline on Treating Tobacco Use and Dependence recommends only counseling for light smokers (defined as smoking fewer than 10 cigarettes per day) and not medications, many tobacco treatment experts recommend medications as an option for light smokers . Pending further trials, clinicians will have to use their best judgment in these situations.
They are too busy. (But they can at least refer to a quitline.)
They have not been trained to be cessation experts. (An excellent curriculum, RX for Change®, is available free at our website—http://smokingcessationleadership.ucsf.edu.)
There is no financial incentive. (Many insurers now pay for counseling. But even if not, attention to smoking should be an integral part of any clinical encounter.)
Lack of available treatments or coverage. (Increasingly health insurers are paying for cessation. And if no other facilities are available, there is always a quitline [1-800-QUITNOW].)
Most smokers can’t or won’t quit. (It is true that the baseline rate for quitting is somewhere around 5%, and even successful clinical trials seldom achieve greater than a 20% quit rate. That means that the majority of smokers are unable to quit even when following evidence-based instructions. But things are not that gloomy. There are now more ex-smokers than current smokers, and the average quitter has previously failed 8-10 times before successfully quitting. And we certainly don’t abandon patients with cancers with even lower rates of cure, such as pancreatic cancer or glioblastomas!)
Smokers are stigmatized for having made a bad choice. (It is true that choosing to smoke was an unfortunate choice, but there may have been powerful tobacco industry or peer pressures that influenced that decision. And don’t forget that most smokers start when they are in their early teen years, a time when the neurologic pathways that form rational judgments are immature.)
Respect for privacy. (Although there is a strong libertarian streak in this country, the pro-health mission of clinicians should take precedence.)
Pushing smokers to quit might cause them to choose another doctor. (In fact, surveys have shown that even smokers with no intention of quitting value clinicians who ask about tobacco use.)
I smoke myself, so I don’t want to seem like a hypocrite. (Although this message only applies to a very small proportion of clinicians, those few smokers should certainly have a lot of empathy for their smoking patients.)
Thus, of the four possible responses to a patients who smoke, one (“I don’t have time to help you”) is unacceptable. The three acceptable responses are to treat the patient in your office, to send him to an expert, or to refer him to a quitline.
Holes in Our Knowledge About Best Practices for Smoking Cessation
Given the above disclaimers, other treatment issues require clarification. Most drug trials last 12 weeks, which is the duration of treatment recommended in most package inserts. Yet, the duration of nicotine addiction has typically been for many years, and drug treatment of other addictive disorders, such as methadone maintenance therapy for heroin addicts, is typically for a very long period. It is quite possible that we are under-treating nicotine dependence.
Another controversy revolves around the use of varenicline, a nicotine brain receptor partial agonist that reduces the craving for nicotine and also lowers the reward from using nicotine. Varenicline has been shown to be a highly effective treatment for smoking cessation. However, its use also carries a finite—but extremely rare—risk of suicidal ideation and action. Whether these risks are due to the drug itself, to nicotine withdrawal, or to the fact that many smokers have underlying depression is unknown, and may be hard to ferret out, given the extremely rare nature of these events (probably about 1 in 50,000). A recent meta-analysis has shown a statistical association of varenicline use with cardiac events in those with a prior cardiac history . The FDA has required Pfizer, the maker of varenicline (Chantix®) to insert black box warnings, and bupropion also carries a black box warning regarding risk of suicide. Clinicians need to balance the important but rare risks from these medications against the hazards of continuing to smoke. In general, while they might not be first-line drugs for many patients, varenicline and bupropion are valuable medications for those smokers who wish to use them or have failed at cessation with nicotine replacement therapy.
As indicated in the USPHS Guideline, evidence does not support the use of pharmacological treatment for pregnant smokers, adolescent smokers, or users of spit tobacco . Nevertheless, many clinicians will prescribe nicotine replacement therapy if counseling is unsuccessful. Although polls have shown that many clinicians believe that nicotine causes cancer, there is no evidence for that fear, and it is a very safe drug compared with the risks of continuing to smoke .
Cytisine, a derivative of an acacia plant, has been used for years in Eastern Europe to help smokers quit, and a recent study showed that short-term use tripled quit rates compared with placebo . Cytisine is not yet available in the United States.
Other Pending Issues
In the face of severe budget crises, many states have slashed their tobacco control budgets, thereby jeopardizing recent progress in smoking prevalence. Notably missing are consumer advocacy efforts to counter those cuts. In the past, health professionals representing the diseases most connected to tobacco use—cancer, heart and lung disease—have been important forces in raising state tobacco taxes and promoting clean indoor air legislation. Whether those advocates can be mobilized to preserve tobacco control programs is not clear.
The “electronic cigarette,” a device to deliver aerosolized nicotine as a means to either substitute for cigarette smoking in restricted venues or to help smokers quit, has received much recent attention . To date the FDA has not found sufficient data on safety nor on their efficacy as cessation aids to approve their use. Until we know better, clinicians should advise smokers to use the counseling and medications that have been approved and recommended.
Increasingly, businesses are refusing to hire smokers, claiming that employees who smoke have higher absenteeism and health costs. This policy survived a challenge in the courts, but at this point is limited to a small—but growing—number of businesses. A variant of that approach, allowed in the 2010 Affordable Care Act, allows employers to charge smokers higher rates for health insurance.
Finally, there is some interest in urging the FDA to regulate the nicotine content in cigarettes. This would entail a gradual reduction over some specified time period (the act enabling FDA regulation of tobacco products prohibits eliminating nicotine, but not reducing nicotine content). The advantage of lowering nicotine is that it would reduce the addictive potential for beginning smokers and possibly induce more smokers to quit. The potential disadvantages are smuggling of high nicotine content tobacco products and compensatory increased smoking to attain desired nicotine levels.
A Tobacco Tipping Point?
In California, the state with the second lowest prevalence of smoking, the 2010 adult prevalence level has declined to 11.9% (Utah is at 9%, but that figure reflects a population that is 50% Mormon, a religion that forbids smoking).
The 2010 national prevalence of 19.3% is a modern low.
Those who continue to smoke are consuming fewer cigarettes (see Fig. 1).
Smoke-free areas continue to proliferate, and now include public spaces like parks, beaches, and some apartment complexes.
Cytisine may join varenicline as a new partial nicotine agonist whose availability may encourage many smokers to attempt to quit, and some to be able to do so.
The fact that physician smoking rates are down to 1% shows how low prevalence can go!
For the first time in many years lung cancer rates among women are declining. Women’s smoking rates have lagged behind that of men. Their smoking rates increased later than men’s, and began to decrease later than men’s. Since lung cancer rates lag behind smoking prevalence by about 30 years or so, the long-awaited decline in women’s lung cancer rates has finally begun.
Smoking is increasingly stigmatized, thereby isolating smokers and creating strong social sanctions against smoking, both in the United States and abroad. It boggles the mind to consider that smoking is now banned in Irish pubs!
New graphic warning pictures will begin to appear on packs of cigarettes, along with the 1-800-QUITNOW message, beginning September 2012, assuming this FDA action withstands a legal challenge.
The Joint Commission will list smoking cessation activities as 1 of 14 possible quality measures for hospitalized patients, from which hospital must choose 4 on which they will be judged.
Despite these encouraging signs, the gap between the magnitude of the problems caused by tobacco use and the amount of resources devoted to correcting it remains enormous. If we push harder, we could be a part of an historic decrease in smoking. This would require both policy advocacy for tobacco control measures plus vigorous smoking cessation efforts. The potential health benefits would be large. But the consequence of failure to act will cost millions of lives.