Nicotine Dependence: Current Treatments and Future Directions

Epidemiology and Tobacco Use in Patients With Cancer

Tobacco use, in particular smoking cigarettes, began an upward trend around the beginning of the 20th century. This trend has been mostly attributed to James Buchanan “Buck” Duke, who introduced the mechanized manufacturing of cigarettes and used aggressive marketing techniques, in addition to other societal forces and circumstances such as the free cigarettes provided with daily rations to all enlisted American soldiers during World Wars I and II. That upward trend continued until a pivotal moment: the release of the landmark first Surgeon General's report on smoking and health in 1964, at which point the evidence from more than 7000 scientific publications on harm from tobacco smoke was put together and received the endorsement of Surgeon General Luther Terry, the highest officer for public health within the US government. That report had an enduring effect on public beliefs and attitudes about tobacco. As an example, a Gallup survey conducted in 1958 found that only 44% of Americans believed smoking caused cancer, whereas 70% believed so by 1969, 5 years after the report was published. The belief that smoking causes cancer continued to rise, and the rate of belief reached 94% by 1990. Furthermore, since 1964 a gradual and almost annual decrease in smoking rates has occurred in the United States, with the rate reaching 15.2% in 2015. This lower rate nonetheless encompasses 45 million Americans who, more than 50 years after the landmark report, continue to use tobacco despite the clear knowledge of harm from its consumption. Other Surgeon General reports subsequently solidified the case against tobacco consumption, and to date 37 of those reports have been dedicated to tobacco (most recently the 50th anniversary report ), focusing on specific topics such as nicotine addiction, secondhand smoke, minorities, women, and youth. Although these efforts have improved public health, disparities in health care unfortunately extend to tobacco consumption, as evidenced by higher smoking rates among American Indians/Alaskan Natives, persons with a diagnosis of mental health or substance use disorders, those who are under the poverty level of income, and the unemployed. It is of importance to note that level of education is inversely related to smoking rates.

Although the trend for smoking among patients older than 45 years who are recovering from cancer has decreased to about the same as for the general population, the prevalence among survivors in the younger age group is still high. Around 40.4% of persons 18 to 44 years of age in the cancer survivors cohort still smoke cigarettes, compared with 24.4% of persons 18 to 24 and 24.1% of persons 25 to 44 years of age in the general population. Nevertheless, one potential confounding factor contributing to these statistics is the high mortality rate in patients with smoking-related tumors. Therefore smokers who would survive less lethal cancers are counted within the younger age group.

Smoking cessation rates in the cancer population seem highly dependent on the disease (tumor) site and its relationship to smoking. As an example, around 80% of patients with lung cancer and 65% of patients with head and neck cancer were reported to have stopped smoking in the year after their treatment compared with 31% of patients with bladder cancer. Other factors increase the likelihood of smoking cessation among patients with cancer, including having a good prognosis, having spent a long time in the hospital (a smoke-free environment), and having treatment-related adverse effects. In particular, adverse effects of treatment such as nausea, difficulty breathing, facial surgery, or difficulty swallowing may make it harder or more difficult to smoke. Consequently, physicians should pay attention to the particular smoking-cessation pattern in patients with cancer. Typically, cancer survivors have an increased chance of a delayed relapse to smoking 1 to 6 months after treatment, in contrast to persons in the general population, who generally relapse within the first week or so of cessation. Unfortunately, it has been reported that some patients with lung cancer who have already abstained from smoking before their diagnosis tend to return to smoking once they are informed of their cancer. Many studies have been published on the benefits of smoking cessation in patients with cancer, with many focusing on cancer treatment–related outcomes ( Table 24.1 ). Unfortunately, almost all published studies to that effect have methodological limitations, such as use of retrospective analyses, nonstandardized tobacco assessment, no biochemical confirmation, and no tracking of behavior after diagnosis. Addressing smoking behavior at the time of diagnosis and throughout treatment and recovery is thus essential for persons with cancer, constituting a continuum of potential teachable moments (i.e., health events that might motivate individuals to adopt risk-reducing behaviors).

Another opportunity for teachable moments arises during lung cancer screening using low-dose computed tomography (LDCT). The US Preventive Services Task Force recommends LDCT screening in individuals 55 to 80 years old with a 30 pack-year smoking history who currently smoke or who have quit within the past 15 years. A systematic review of two randomized controlled trials (RCTs) and three observational studies found that although LDCT itself does not influence smoking behavior, positive results (i.e., finding a nodule or a tumor) were associated with increased abstinence. A more recent analysis of 18,840 current and former smokers from the National Lung Screening Trial found that false-positive screening results were associated with modest increases in abstinence among smokers over the course of a 5-year follow-up period. These studies have similar limitations to other studies about smoking cessation in cancer patients, including nonstandardized assessment of smoking behavior and no biochemical verification of abstinence. Therefore more research is needed on the effectiveness of lung cancer screening as a teachable moment for smoking cessation. It will also be important to study the effectiveness of offering evidence-based smoking cessation interventions at the time of lung cancer screening, which have the potential to further motivate smokers to quit beyond lung cancer screening itself.

Reward Pathway and Biologic Characteristics of Addiction