Smoking Before
Menopause Increases Breast Cancer Risk, Post Menopause May Lower Risk
Never smoking and
passive smoking in childhood or adulthood were not associated with an
increase in breast cancer risk
Jan. 24, 2011 -
Smoking before menopause, especially prior to giving birth, may be
associated with a modest increase in the risk of developing breast
cancer, says a new report. The study also found a possibility that
smoking after menopause my reduce the risk.
"Breast cancer
is the most common cancer to affect women worldwide," according to
background information in the article appearing in the January 24 issue
of Archives of Internal Medicine, one of the JAMA/Archives
journals.
"Tobacco smoke
contains potential human breast carcinogens, including polycyclic
aromatic hydrocarbons, aromatic amines and N-nitrosamines."
Using data
collected from the Nurses' Health Study, Fei Xue, M.D., Sc.D., of
Brigham and Woman's Hospital and Harvard Medical School, Boston, and
colleagues examined the records of 111,140 women from 1976 to 2006 for
active smoking and 36,017 women from 1982 to 2006 for passive
(secondhand) smoking.
A total of 8,772
breast cancer cases developed during follow-up. The development of
breast cancer was associated with a higher quantity of current and past
smoking, smoking for a longer period of time, younger age at smoking
initiation and more pack-years (product of the number of packs per day
and the number of years that quantity was smoked) of smoking.
"Smoking before
menopause was positively associated with breast cancer risk, and there
were hints from our results that smoking after menopause might be
associated with a slightly decreased breast cancer risk," the authors
write.
"This difference
suggests an antiestrogenic effect of smoking among postmenopausal women
that may further reduce their already low endogenous estrogen levels."
Conversely,
never smoking and passive smoking in childhood or adulthood were not
associated with an increase in breast cancer risk.
Exposure to
parents who smoked while living in the same house, passive smoking while
at work or at home and the number of years living with someone who
smoked were not related to increased risk of breast cancer after
adjusting for other possible factors.
"In the present
study, we created an index of active smoking that integrates quantity,
age at which one started smoking and duration of smoking," the authors
conclude.
"The results
suggested that, although an elevated risk for light smokers and moderate
smokers was not apparent, heavy smokers who started smoking early in
life, smoked for a long duration and smoked a high quantity were at the
highest risk of breast cancer, supporting an independent and additive
effect from various smoking measures on breast carcinogenesis."
The Nurses'
Health Study is supported by a grant from the National Cancer Institute,
National Institutes of Health.
Keep up with the latest news for senior citizens, baby
boomers
Jan. 24, 2011 -
Smoking before menopause, especially prior to giving birth, may be
associated with a modest increase in the risk of developing breast
cancer, says a new report. The study also found a possibility that
smoking after menopause my reduce the risk. 