new study of breast cancer patients in Japan has revealed that decades of
smoking are associated with an increased risk of early death in pre-menopausal
women diagnosed with breast cancer. This finding strengthens the case for
smoking cessation, particularly as breast cancer in premenopausal women has
significantly worse prognosis than it has in postmenopausal women.
Smoking is injurious to health. It harms
almost every organ of the body and is also responsible for many types of
cancers and health problems. While lung
is a well-documented health hazard linked to smoking, the
habit also raises the risk of death from chronic obstructive pulmonary disease
, heart disease, stroke and other cancers, including breast
is the most commonly occurring cancer in women worldwide.
Previous studies have suggested that smoking significantly increases
the risk of developing breast cancer in premenopausal women.
However, very few studies have investigated the relationship between active smoking and risk of death among breast cancer
Also, the results of these studies were found to be
Some studies have suggested that women
who are active smokers have a higher risk of death from any cause after being
diagnosed with breast cancer while others have shown no association between
active smoking and overall survival in breast cancer patients. Trying to
establish this relationship is of particular importance because smoking might
be one of the modifiable lifestyle factors that might improve the prognosis of
breast cancer patients.
For the study, the
research team followed 848 female breast cancer patients aged 21 years or
over at the Miyagi Cancer Centre Hospital (MCCH) between January 1997 and
December 2007. The researchers assessed the patients' active or passive
status and menopausal status with the help of a
self-administered questionnaire. The patient follow-up continued till December 31, 2010.
A total of 302 women died
during the 607 year follow-up period. The researchers observed that premenopausal women with breast cancer who
smoked for more than 21.5 years had a 3.1 times higher risk of dying from any
cause and a 3.4 times higher risk of dying from breast cancer.
premenopausal patients, current smokers tended to have the shortest survival
rate. Shorter survival was also noted among women who started smoking early
(≤20 years) and those who smoked heavily (>21 cigarettes per day). The
findings clearly indicated a decrease in
survival rate with an increase in the duration of smoking.
increased risk was especially relevant to pre-menopausal women with estrogen
receptor (ER+) or progesterone receptor (PR+) tumor.
This relationship might be
related to estrogen-like substances found in active tobacco
smoke that might accelerate the progression of hormone receptor-positive
tumors. Detailed analysis of the study data suggests that premenopausal ER+ or
PR+ cancer patients with a longer history of smoking tended to have more
advanced tumors compared to women who had never smoked or had only smoked for a
The study did not
suggest any significant association between smoking status and survival among
postmenopausal breast cancer patients.
One possible reason for
this higher risk of death among premenopausal women could be that lifestyle habits related to smoking
might have influenced the prognosis of breast cancer. Smoking women were found
to be less educated, physically inactive and they consumed fewer green
vegetables and fruits. However, further studies are needed to clarify the
association between survival and smoking-related lifestyles.
Long-term smoking might
also affect the immune system and cause immunological
Such delirious effects
of smoking on hormones and the immune system, in addition to the above
mentioned lifestyle factors could contribute to the
increased risk of all-cause
and breast cancer-specific death among
premenopausal women with ER+ or PR+ breast cancer.
The study did not find any
association between exposure to passive smoking and survival of breast cancer
large-scale studies are needed to confirm these results, smoking cessation could contribute to a significant reduction in breast
Breast cancer patients should be informed about the
importance of smoking cessation in a clinical setting. Moreover, considering the higher risk of death among
premenopausal women with a longer duration of smoking, smoking control measures
targeting young girls is urgently needed.
The study has been
published in Cancer Science