Changes in cigarette smoking behavior among breast cancer and unaffected women – A prospective study in the MARIE cohort

1Introduction

Smoking cigarettes is a major risk factor for adverse cancer treatment outcomes. Continuing to smoke after a cancer diagnosis can increase the risk of all-cause mortality, cancer recurrence, and side effects during cancer treatment 1234 . Quitting smoking as early as possible can reduce these risks and can increase survival [5] . Despite these benefits to quitting smoking, studies have shown that up to 50 % of cancer patients continue to smoke after diagnosis 678 . One study specifically on breast cancer patients found that only 17 % of female breast cancer patients who smoked reported reducing or quitting smoking within one year of breast cancer treatment [9] .

The addictive properties of nicotine make quitting smoking difficult. The physiological aspects of withdrawal symptoms, such as irritability and anxiety, can make sustained smoking cessation difficult. To aid in quitting, pharmacotherapy (i.e., FDA-approved nicotine replacement therapy) and behavioral support (i.e., cognitive behavioral therapy) are recommended to deal with both the physical addiction of nicotine and the urges of smoking [1011] . As relapse to smoking is common, extended therapy (i.e., lasting 6 months) has been found to be successful in increasing quit rates than brief interventions [12] .

Studies have examined whether the health shock of a cancer diagnosis can put into motion an assessment of health risks, updating one’s own information about the consequences of smoking cigarettes [13] , and then to a decision to quit smoking. Researchers have described this time of being diagnosed with a cancer diagnosis as a “teachable moment” that can motivate changes in health behavior [14] . Yet, to understand whether a behavioral change such as quitting smoking is motivated by a cancer diagnosis, or whether behavior change is a part of aging, comparison with a non-cancer population is needed.

Few studies have compared smoking behavior in patients with cancer to a non-affected comparison group. One large US prospective study of people who smoked at baseline found 2- and 4- year quit rates higher in those who had a recent cancer diagnosis than those who did not [15] . A study from the United Kingdom also examined short-term quit rates (0–2 and 2–4 years) but found no difference between cancer and non-cancer patients [16] . Studies have examined whether the type of cancer plays a role in changing smoking habits. For example, one study compared tobacco- and non-tobacco- related cancers in adults who used tobacco to those cancer-free and found no difference in quitting smoking between those who had a non-tobacco related cancer and those who did not have cancer [17] . In the same study, a diagnosis of a tobacco-related cancer was associated with a higher odds of smoking cessation compared to no cancer [17] . When examining breast cancer, a prospective study using data from a Danish cohort found no differences in changes in smoking between cancer and cancer-free women [18] . Yet, a Norwegian study found female breast cancer survivors and female colorectal cancer survivors had higher quit rates than cancer-free women [19] . As seen with these mixed findings, whether smoking changes are motivated by a cancer diagnosis is unclear. Furthermore, these previous studies looked at only one follow-up time point of 10 years or less, or at short-term quit rates, and thus changes (including starting smoking again) over multiple time points are unknown.

With a large cohort of breast cancer and unaffected women spanning up to 18 years of follow-up, this study aimed to examine whether a breast cancer diagnosis, which has not historically been considered a smoking-related cancer, encourages quitting smoking cigarettes. As data were collected at three follow-up time points, whether women quit and start again was also examined.