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 Among more than 800 women with breast cancer, those who had smoked
for more than two decades had at least triple the odds of dying of
any cause, or from breast cancer in particular, compared with women
who never used cigarettes.
Fewer years of smoking were also linked to an increased risk of
death from breast cancer, but the extra risk was so small that it
might have been due to chance.
Other studies have explored the connection between smoking and
survival among breast cancer patients, but the current research is
among the first to assess the impact of the duration of smoking on
outcomes for women with this type of tumor, said study co-author Dr.
Masaaki Kawai, a breast oncologist at Miyagi Cancer Center Hospital
in Japan, in email to Reuters Health.
Worldwide, breast cancer is the most common malignancy in women.
About one in nine women will eventually develop it, according to the
National Institutes of Health. The risk increases with age, from 1
in 227 at age 30 to 1 in 26 by age 70. Factors such as obesity,
inactivity, alcohol use or early menstruation can increase the risk.
For the current study, Kawai and colleagues followed 848 women who
were treated at the Miyagi Cancer Center Hospital between 1997 and
2007 for newly diagnosed breast cancer.
Women who described themselves as current smokers were typically
younger when their breast cancer was diagnosed, about 49 years old
on average, compared with 53 for women who claimed to be former
smokers and 58 for nonsmokers.
The current smokers also tended to weigh less, have more advanced
tumors, and have fewer health complications than the other women in
the study.
With half of the women in the study followed for at least seven
years, the researchers saw 170 deaths from all causes – including
132 deaths from breast cancer.
Roughly one third of the women hadn’t yet gone through menopause
when they started the study. In this subset, those who had smoked
for more than about 21 years were three times more likely to die of
any cause, and nearly three and a half times more like to die of
their breast cancer, than those who never used cigarettes.
Researchers also examined exposure to second-hand smoke among women
whose husbands were current or former smokers and found no
significant impact on the women’s risk of death from any cause or
from breast cancer specifically.
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One limitation of the study is its reliance on patients to
accurately report information about their exposure to cigarettes,
the researchers acknowledge in the journal Cancer Science. The study
also lacked data on second-hand smoke that didn’t come from the
women’s spouses.
Even so, the findings add to a growing body of research pointing to
the specific risks smoking poses for women with breast cancer, said
Peggy Reynolds, a researcher at the Cancer Prevention Institute of
California and Stanford University School of Medicine.
“There are now quite a few studies suggesting that active smokers
diagnosed with breast cancer have poorer survival – not to mention
accumulating evidence that smokers may have a greater risk of
developing breast cancer,” Reynolds, who wasn’t involved in the
study, said by email.
This study, however, didn’t look at whether smoking causes breast
cancer.
Even if not all of the evidence is conclusive, it should still be
enough to motivate patients to abandon cigarettes, said Mia Gaudet,
strategic director of breast and gynecologic research at the
American Cancer Society in Atlanta, in an email.
“Regardless of whether or not a woman has breast cancer, quitting
smoking is likely to be the best lifestyle change a woman can make
to improve her health,” she said.
SOURCE: http://bit.ly/1TOoirO Cancer Science, online July 14, 2015.
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