April 13, 2004
Lung Cancer Cause Different for Women
CHICAGO --- Tobacco use in American women rose dramatically during
the 20th century, resulting in a 600 percent increase by the year 2003
in the number of women who died of lung cancer. In the same period, the
number of lung cancer deaths in men declined.
Lung cancer has now surpassed breast cancer as the leading cause of
cancer death, accounting for one fourth of all female cancer deaths last
year. In 2004, lung cancer will cause as many deaths in women as breast
and all gynecologic cancers combined.
Several studies have reported that women are more susceptible than
men to the lung cancer-causing effects of cigarette smoking, although
this issue remains somewhat controversial.
What is not controversial, according to Northwestern University
researcher Jyoti D. Patel, M.D., is that lung cancer appears to be a
different disease in women.
In an article in the April 14 issue of The Journal of the American
Medical Association, Patel and colleagues from Memorial Sloan-Kettering
Cancer Center, New York, discuss differences in the biology of lung
cancer between the sexes, including genetic mutations, increased
production of certain enzymes that help trigger cancer growth and
hormonal changes.
“Genetic, metabolic and hormonal factors all are important to
the way women react to carcinogens and lung cancer. This information
should impact how we evaluate and screen patients who smoke and how we
direct smoking cessation and lung cancer prevention programs,”
Patel said.
For example, women are more likely than men to develop
adenocarcinoma, a subtype of lung cancer. Adenocarcinoma, once a rare
type of lung cancer, is now the most common type of lung cancer and is
less associated with smoking than other types of lung cancer.
Adenocarcinoma is the most common form of lung cancer present in young
persons, those who never smoked and women of all ages.
Patel said that this difference in prevalence between sexes suggests
basic differences in lung cancer.
“Mounting evidence suggests that these differences could be
due, in part, to estrogen,” Patel said.
Research has found that lung cancer cells have more estrogen
receptors on their surface than normal lung cells. Other studies have
shown an association between estrogen replacement therapy and
development of adenocarcinoma of the lung and a positive interaction
between estrogen replacement, smoking and development of adenocarcinoma
of the lung, Patel said.
Patel also noted that once women have lung cancer, they experience a
survival benefit that is not accounted for solely by a longer life
expectancy or imbalance of other prognostic factors.
Most major studies for lung cancer prevention in the past have
excluded women. The researchers believe it is critical that future lung
cancer research specifically include a portion of women that reflects
the true incidence of lung cancer in females.
“Given these differences, it is critical that future lung
cancer research specifically include a proportion of women that reflects
the true incidence of lung cancer in females,” they said.
Perhaps the biggest challenge lies in avoiding a similar sad story in
other parts of the world, the researchers said. Sociocultural
constraints that previously discouraged tobacco use by women continue to
weaken in many developing countries. Around 20 million women have
started smoking in China in the past 10 years, and after aggressive
promotional campaigns in Japan that targeted women and girls, smoking
among women there has doubled in just five years.
Patel and co-authors caution that the extraordinary increase in lung
cancer rates seen in American women in the 20th century will be repeated
in women of developing countries during this century unless effective
tobacco control measures are implemented.
Patel is instructor in medicine in the division of
hematology/oncology at the Feinberg School of Medicine, a researcher at
The Robert H. Lurie Comprehensive Cancer Center of Northwestern
University and an attending physician at Northwestern Memorial
Hospital.
Her co-researchers on the study were Peter B. Bach, M.D., assistant
attending physician in the department of epidemiology and biostatistics,
and Mark G. Kris, M.D., chief, thoracic oncology service, Memorial
Sloan-Kettering Cancer Center. Kris was senior author on this
article.
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