In a prospective study of 848 women with breast cancer who were followed for a median of 6.7 years, premenopausal women who smoked for more than 21.5 years had a 3.1-times higher risk of dying from any cause as well as a 3.4-times higher risk of dying from breast cancer. These links were not apparent among post-menopausal women.
There was also some suggestion that the increased risks seen in premenopausal women were especially relevant to women whose cancers expressed both the estrogen receptor and the progesterone receptor.
"Overall, this work is monumental in advising patients about how their smoking might affect their outcome," said Dr. Yuko Minami, co-author of the Cancer Science study. "Hopefully this paper will serve to reduce the number of breast cancer patients who continue to smoke."
Kakugawa et al. Smoking and survival after breast cancer diagnosis in Japanese women: A prospective cohort study. Cancer Science. 2015;EPub. DOI: 10.1111/cas.12716 [Abstract]