MELISSA BLOCK, host:
Staying with health issues, there are two studies in this week's Journal of the American Medical Association that look at rates of the most lethal type of cancer: lung cancer. The vast majority of patients who get lung cancer smoked at some point in their lives. Now researchers suggest two ways smokers or former smokers might protect themselves against the disease. NPR's Patricia Neighmond reports.
PATRICIA NEIGHMOND reporting:
Even though most people who get lung cancer have smoked, only 20 percent of lifetime smokers ever get lung cancer. Researchers wanted to know why. They knew genetics played some role, but some studies suggested diet may also play a role. Dr. Margaret Spitz is an epidemiologist at the MD Anderson Cancer Center in Houston. She decided chemical compounds called phytoestrogens were a good target for investigation.
Dr. MARGARET SPITZ (MD Anderson Cancer Center): Why phytoestrogens? Well, Asian countries generally consume much higher levels of phytoestrogens than do Western countries. What are phytoestrogens? They are plant-derived compounds which have weak estrogenlike activity.
NEIGHMOND: Their essentially fibrous. Soy products like tofu are rich in phytoestrogens; so are certain grains, certain fruits like berries and many vegetables, including carrots, lettuce, spinach and broccoli. Previous studies in animals and in test tubes found that phytoestrogens may protect against cancer.
Dr. SPITZ: We know that they slow down the cell cycle, and that gives cells a chance to repair any DNA damage that occurs. And we also know that these compounds promote programmed cell death, which is good because it enables cells which are damaged and which the DNA has been unable to be repaired and that these cells could die, and therefore this protects against the development of cancer.
NEIGHMOND: In the study, Spitz and researchers interviewed over 3,400 people. About half had lung cancer. They looked at each person's consumption of phytoestrogens. They found the more people ate, the more they reduced their risk of lung cancer even if they smoked. Those who consumed the most phytoestrogens reduced their risk of lung cancer by 46 percent. A second study in a journal from Denmark shows that cutting down the number of cigarettes smoked can also help. Dr. Larry Dacey is a cardiothoracic surgeon at Dartmouth-Hitchcock Medical Center.
Dr. LARRY DACEY (Dartmouth-Hitchcock Medical Center): The fascinating thing about this particular article was it saying, `OK, what if you can't stop? Does cutting down make a difference? If you at least decrease the amount that you smoke, will that improve things?' And bottom line is yes.
NEIGHMOND: Danish researchers followed nearly 20,000 people over 30 years. Some were heavy smokers. Some smoked only one to 14 cigarettes a day. Some quit smoking. Others reduced the number of cigarettes smoked. Those who quit and those considered light smokers were the least likely to get lung cancer. But those who reduced their intake by half also reduced their lung cancer risk by 27 percent. Dr. Dacey.
Dr. DACEY: So there is hope for people that even--they've tried everything. They've tried quitting two or three times. You know, meet them halfway. You know, say, `OK, instead of smoking two packs a day, cut down to one or a half a pack a day or limit yourself to four cigarettes.' Normally we would never say that, but now we have evidence to say that, yes, that's probably a good thing to do.
NEIGHMOND: Bottom line, of course, the best thing to do is to quit altogether. Diseases like emphysema and heart disease are more common than lung cancer and are clearly linked to smoking. Studies have shown no decrease in these diseases when people simply cut down. Patricia Neighmond, NPR News.
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