Smoking behaviours in current cancer patients

Key message

One in five cancer patients reported daily or occasional smoking, highlighting the need to integrate smoking cessation counselling and interventions into cancer care.

Background

It is known that smoking is a risk factor for many types of cancer (see the Smoking Prevalence section for more details). Less commonly known, however, is the fact that cancer patients who continue smoking after diagnosis can have worse outcomes than non-smoking patients.

While a cancer diagnosis often motivates smokers to quit, some cancer patients may continue to smoke after their diagnosis, which can negatively affect their treatment outcomes and survival.¹ Patients who quit smoking at the time of their diagnosis are more likely to recover from their cancer than those who do not.² This is because smoking reduces the effectiveness of treatment, particularly radiation therapy and chemotherapy, and increases the risk of side effects and complications of treatment.^1-4 Smoking also increases the risk of developing a second primary cancer (i.e., a type of cancer different from the original diagnosis) or having the cancer recur.^{1, 2, 5-6} Quitting smoking can ultimately help to improve a patient’s prognosis and influence their quality of life.^{2, 7}

Through System Performance reporting, smoking prevalence and other smoking indicators have been reported for many years, with a focus on reducing the incidence of cancers caused by tobacco use. This Special Feature expands on that work by looking at smoking behaviour after a cancer diagnosis. This perspective provides insight that can help clinicians and policy makers to develop, discuss and promote cessation activities specific to cancer patients to lessen or minimize poorer outcomes.

Methods

Self-reported data from the Canadian Community Health Survey (CCHS) were used to generate descriptive statistics on smoking behaviours in current cancer patients compared with those who do not currently have cancer (the non-cancer-patient population). Cancer patients were those who reported in the 2011–14 surveys that they currently have cancer. Multiple years of data were combined to increase the sample size of respondents who were cancer patients and thus reduce the variability of the estimate. The non-cancer-patient population comprises those who reported that they did not currently have cancer. Smoking status was derived from the subset of these respondents who answered questions relating to smoking cigarettes. Respondents aged 12 or older were included in the results. Estimates were age-standardized to the 2011 Canadian population to account for differences in age distribution across the cancer patient population compared with the non-cancer-patient population.

The results focus on the smoking status of current cancer patients at the time of the survey only. We were unable to identify patients who no longer smoked but did when they were first diagnosed with and treated for cancer or who were smokers earlier in their lives. The results also do not differentiate types of cancer.

Results

Capturing cancer cases in the Canadian Community Health Survey

The Canadian Cancer Society reports the prevalence of cancer in the Canadian population as approximately 2.4%, representing just over 800,000 Canadians living with a cancer diagnosed in the past 10 years.⁸ In the 2011–14 CCHS, 2% of respondents reported that they currently had cancer.

Smoking behaviours

About one in five cancer patients (20.1%) reported daily or occasional smoking (2011–14 data). This rate was not statistically different from the non-cancer-patient population—19.3% of respondents in this category reported smoking daily or occasionally (Figure 1.3).

Male cancer patients were more likely to report daily or occasional smoking than female cancer patients (22.2% vs. 18.7%), though this difference was not significant (Figure 1.3).

Conclusions

The data suggest that a surprisingly high percentage of cancer patients in Canada continue to smoke after their diagnosis, which is a concerning finding. Our findings align with the results of other research, which have shown that 20–30% of patients continued to smoke after their diagnosis.^{7, 9-10}

It is possible that cancer patients who continue to smoke after diagnosis either try to quit and fail to do so or believe that quitting will not help them (i.e., they already have cancer so quitting will not make a difference).³ It is also possible that the type of cancer a patient is diagnosed with may influence their smoking choices. For instance, studies have shown that patients with lung, head or neck cancers are more likely to quit smoking after their diagnosis.^{3, 9} This could be because physicians are more likely to discuss smoking with patients who develop these types of cancer or because patients can draw a clear causal link between their diagnosis and their smoking dependence.¹¹ Patients with other types of cancer (e.g., colorectal, breast or prostate) may not associate their diagnosis with their smoking habits and thus may not be driven to quit.^{3, 9}

Given the risk of increased morbidity, poor treatment outcomes and mortality associated with continued smoking, smoking cessation interventions are crucial for cancer patients who smoke. Many patients are not able to quit without support,¹¹ meaning that health care professionals should offer cessation counselling to smokers at the time of diagnosis or when a malignancy is suspected, regardless of whether or not it is a smoking-related cancer. The sooner cessation treatment is offered after diagnosis the higher the likelihood that abstinence from smoking will continue.³

References

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2. National Cancer Institute. Smoking in Cancer Care (PDQ®) [Internet]. Bethesda (MD): National Cancer Institute; 2014 [updated 2014 Jun 27; cited 2015 Oct 20]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK65764/.
3. Park ER, Japuntich SJ, Rigotti NA, Traeger L, He Y, Wallace RB, et al. A snapshot of smokers after lung and colorectal cancer diagnosis. Cancer. 2012 Jun 15;118(12):3153-64.
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8. Canadian Cancer Society's Advisory Committee on Cancer Statistics. Canadian Cancer Statistics 2015. Toronto (ON): Canadian Cancer Society; 2015 May. 150 p.
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10. Tseng TS, Lin HY, Moody-Thomas S, Martin M, Chen T. Who tended to continue smoking after cancer diagnosis: the national health and nutrition examination survey 1999-2008. BMC Public Health. 2012;12:784.
11. Pinto BM, Trunzo JJ. Health behaviors during and after a cancer diagnosis. Cancer. 2005 Dec 1;104(11 Suppl):2614-23.