NPR did a great job covering this last night.  Even better is to quite
smoking but I suspect you have heard that ad nauseum.
http://www.npr.org/templates/story/story.php?storyId=4866208

Veggies, fruit may ward off lung cancer


BY DELTHIA RICKS
STAFF WRITER

September 28, 2005

Bolstering the diet with fruits, vegetables and legumes rich in
plant-based estrogens tends to protect against lung cancer,
researchers report in an analysis published today.

Conducted by a team of cancer-prevention researchers at M.D. Anderson
Cancer Center in Houston, the analysis marks one of the few studies -
and to date the largest - to examine dietary effects on lung tumor
development. Lung cancer is the most common cause of cancer-related
deaths in men and women in the United States.

Plant-based estrogens, or phytoestrogens, come in three main classes:
isoflavones, lignans and cumestrans, with isoflavones and lignans the
most widely seen in nature. All act as weak estrogens with varying
capacities to influence the life and death of cells.

Isoflavones, the most common, are found in a range of foods,
especially soybeans, chickpeas, yams and red clover. Lignan sources
include spinach, broccoli, tea, carrots and rye grains. Cumestrans are
found in beans, peas, spinach and sprouts.

"Basically we found that people with lung cancer were less likely to
consume these foods," said Matthew Schabath, a postdoctoral fellow
specializing in cancer prevention.

"What we saw was quite interesting in terms of protective effects in
'never smokers' and former smokers," Schabath added. But for reasons
that could not be easily explained, benefits were not apparent in
current smokers, according to the findings, reported in today's issue
of the Journal of the American Medical Association.

Schabath and colleagues studied 1,674 lung cancer patients and 1,735
people without the disease from July 1995 to October 2003.
Participants answered questionnaires on food frequency. Researchers
were particularly interested in quantifying dietary intake of specific
phytoestrogens.

"Phytoestrogens have a variety of protective effects that have been
shown in experimental models [lab animals] and lab models [Petri
dishes] to have various chemo-effects," Schabath said.

Some of those effects have been as antioxidants, which means they can
inhibit the prevalence of rogue oxygen molecules called free radicals.
Schabath defined other effects of weak estrogens as limiting
angiogenesis, the growth of blood vessels required by tumors and
inducing programmed cell death.

Schabath pointed to Asians who consume robust quantities of
phytoestrogens, especially in the form of soy-based foods, as having
lower rates of cancer.

But while that may be true for many types of malignancies it is not so
for lung cancer, especially in China, where the disease has reached
epidemic proportions. The World Health Organization estimates the
number of lung cancer patients in China will increase by 1 million a
year through 2025.

A second study in the same issue by researchers in Denmark found that
cutting the number of cigarettes smoked daily could reduce lung cancer
risk for those who cannot completely break the habit.

Doctors Lawrence Dacey and David Johnstone of Dartmouth-Hitchcock
Medical Center in New Hampshire wrote in a critique of both analyses
that while the phytoestrogen findings are good news, the old "stop
smoking" message is even better.

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