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Quitting smoking reduces risk for breast cancer death
Breast cancer survivors who quit smoking after their diagnosis reduced their risk for death 33%, according to findings from a population-based prospective observational study.
The 2014 Report of the Surgeon General on the consequences of smoking suggested that there may be a relationship between breast cancer and smoking. Further, previous research indicated that risk for breast cancer in smokers was affected by the initiation of a smoking habit and how long a patient had been smoking.
“Our study shows the consequences facing both active and former smokers with a history of breast cancer,” Michael N. Passarelli, PhD, MPH, MS, cancer epidemiologist at University of California San Francisco School of Medicine, said in a press release. “About one in 10 breast cancer survivors smoke after their diagnosis. For them, these results should provide additional motivation to quit.”
Passarelli and colleagues used data from the Collaborative Breast Cancer and Women’s Longevity Study to evaluate the association between smoking status — before and after diagnosis — and mortality in 20,691 women aged 20 to 79 years who were diagnosed between 1988 and 2008. Researchers recontacted a subset of 4,562 women from that population at a median of 6 years following diagnosis.
During a median of 12 years, 6,778 women had died, including 2,894 who died of breast cancer.
Women who were active smokers 1 year prior to their diagnosis (20%) were more likely to die of breast cancer (HR = 1.25; 95% CI, 1.13-1.37), cardiovascular disease (HR = 2.08; 95% CI, 1.8-2.41), respiratory cancer (HR = 14.48; 95% CI, 9.89-21.21) or other respiratory disease (HR = 6.02; 95% CI, 4.55-7.97) than never smokers.
The 10% of the women who continued to smoke after diagnosis were more likely to die of breast cancer than never smokers (HR = 1.72; 95% CI, 1.13-2.6).
Women who quit smoking after diagnosis had a 33% (HR = 0.67; 95% CI, 0.38-1.19) reduced risk for dying of breast cancer and a 61% (HR = 0.39; 95% CI, 0.16-0.95) reduced risk for dying of respiratory cancer when compared with women who continued to smoke after diagnosis.
“Smoking cessation programs should be considered part of cancer therapy,” Passarelli said in the release. “Recent policy statements from leading research and clinical organizations are now urging oncologists to be as aggressive in getting their patients to stop smoking as they are in treating the cancer.” – by Anthony SanFilippo
Disclosure: Passarelli reports no relevant financial disclosures. One other researcher reports holding use patents for the chemopreventive use of calcium and the colorectal chemopreventive use of aspirin.
Perspective
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In the recent study in Journal of Clinical Oncology by Passarelli and colleagues, the researchers found that in a large, prospective cohort study of over 20,000 women, smoking before or after breast cancer diagnosis was associated with increased mortality.
It is not surprising that smokers had much higher rates of death from respiratory cancer and respiratory disease than never smokers. Additionally, the link between smoking and breast cancer mortality is becoming more well-established, as seen in this study and others, such as the 2014 Surgeon General’s Report.
Interestingly, the researchers demonstrated a benefit of stopping smoking on mortality from respiratory cancer (HR = 0.39; 95% CI, 0.16 to 0.95) and even a nonstatistically significant trend toward reduction in death from breast cancer (HR = 0.67; 95% CI, 0.38 to 1.19).
These finding add to the growing body of evidence that even among patients who already suffer from a tobacco-caused disease, including cancer, there is a strong benefit in their stopping smoking.
Numerous studies now exist that clinical outcomes for multiple types of cancer are improved if tobacco users quit. These include better results with surgical, radiation and chemotherapies.
Active smokers often require higher doses of chemotherapy, and the associated higher rates of toxicity have greater side effects from radiation therapy and have more surgical complications than nonsmokers. Stopping smoking also reduces cancer recurrence as well as development of second primary malignancies.
It is important for oncologists and other providers to realize that a cancer diagnosis alone is not sufficient to assure that smokers will successfully stop. It may increase motivation and desire to quit, but not necessarily successful cessation.
In this study, only 10% of smokers continued to smoke after their breast cancer diagnosis. In other studies, as many as 40% to 50% of smokers with cancer diagnoses continue to smoke, even if they do not share that information with their oncologist out of fear for negative reactions and judgment.
They do not continue to smoke because they do not know any better or do not care. It is because tobacco use is the most addictive behavior in our society. For this reason, we need to be sure to offer intensive tobacco dependence treatment to all patients, especially those diagnosed with cancer.