Study: Smoking Linked to Shortened Breast Cancer Survival

By Stacy Simon

Breast cancer survivors who are smokers and continue to smoke after their diagnosis are more likely to die from breast cancer than breast cancer survivors who have never been smokers, according to findings from the Collaborative Breast Cancer Study. The smokers were also more likely to die from respiratory cancer, respiratory disease, or cardiovascular disease.

The Collaborative Breast Cancer Study was conducted by the University of Wisconsin, Dartmouth College, and Harvard University. It involved more than 20,000 women who were diagnosed with breast cancer between 1988 and 2008. It is the largest study of length of survival according to smoking habits in women with a history of breast cancer, and the first study to look at smoking habits both before and after diagnosis with breast cancer.

The study compared the causes of death among 4 groups: women who never smoked, women who smoked but quit at least 1 year before diagnosis, women who smoked and quit after diagnosis, and women who smoked and continued to smoke after diagnosis. The highest risks of death as a result of breast cancer were observed among long-term smokers, women who smoked heavily, or former smokers who quit fewer than 5 years before their breast cancer diagnosis.

About 10% of the women were smokers who kept smoking after diagnosis, which is consistent with a study by American Cancer Society researchers that found about 1 in 10 cancer survivors still reports smoking about 9 years after a diagnosis. These women were more likely than non-smokers and former smokers to die of breast cancer.

The researchers also found that women who quit smoking after their diagnosis were significantly less likely to die from respiratory cancer, respiratory disease, or cardiovascular disease than women who continued to smoke. The women who quit were also less likely to die overall or from breast cancer specifically, although neither of these results were statistically significant. Still, the authors say their study reinforces the importance for women with breast cancer to quit smoking.

“Our study shows the consequences facing both active and former smokers with a history of breast cancer,” said co-author Michael Passarelli, PhD. “About one in ten breast cancer survivors smoke after their diagnosis. For them, these results should provide additional motivation to quit.”

The paper was published January 25, 2016 in the Journal of Clinical Oncology.

Citation: Cigarette Smoking Before and After Breast Cancer Diagnosis: Mortality From Breast Cancer and Smoking-Related Diseases. Published January 25, 2016 in the Journal of Clinical Oncology. First author Michael N. Passarelli, PhD, University of California, San Francisco, San Francisco, Calif.

Reviewed by: Members of the ACS Medical Content Staff