Is there anything an ex-smoker can do to decrease the chances of getting lung cancer or at least catch it early?
No. Quitting is really the only way to cut the risk of lung cancer, said Dr. Michael Thun, who heads epidemiology research for the American Cancer Society.
Smoking damages the lungs and the more years you smoke, the greater the damage. In general, it takes six "hits," or bits of damage to DNA, to produce a lung cancer. With the first hit from a carcinogen, a lung cell begins to develop into a fast-growing patch of similar cells.
If a person quits after, say, three hits, precancerous "sleeper cells are unlikely to become cancer," said Thun. But if you resume smoking or never quit in the first place, these "sleeper cells" acquire more hits and ultimately become full-blown cancers.
As for catching lung cancer early, there is still no recommended screening test. That's because authorities are waiting for results from a large clinical trial called NLST (National Lung Screening Trial). It won't produce results for several years, said Dr. Phillip Boiselle, director of thoracic imaging at Beth Israel Deaconess Medical Center in Boston.
The NLST trial is designed to see which screening test -- chest X-ray or spiral CT scan -- is more effective at reducing deaths by catching lung cancer early.
Chest X-rays subject a person to low levels of radiation, but can miss 30 percent of nodules that might be cancer. On the other hand, they are not too likely to yield false positives - results that suggest cancer when there is none.
Spiral CT scans, which can cost several hundred dollars and are often not covered by insurance, are better than chest X-rays at finding very small nodules, but they expose subjects to 15 times as much radiation and are so sensitive they pick up many things that are not cancer yet -- but may subject people to more tests and considerable anxiety.
If you're worried about lung cancer, you can ask your doctor about getting a chest X-ray or spiral CT scan, but remember, at this point, the doctor's advice will be based on an educated guess, not clear science.
I hear a lot about probiotics. What are they, and what are they for?
Probotics are "good" bacteria and they've been consumed, in yogurt and other products, for hundreds of years in Europe and Asia to prevent and treat a variety of gastrointestinal ailments.
Their popularity in the United States is growing as dietary supplements designed to restore a healthful balance between good and bad bacteria in the gut.
Restoring this balance can be especially important while taking antibiotics, which kill off good as well as bad bacteria, leaving many people with cramps and diarrhea.
"Probiotics definitely help with acute diarrhea," said Dr. Sherwood Gorbach, an infectious disease specialist at Tufts University School of Medicine. He and a colleague, biochemist Barry Goldin, developed Culturelle, which contains the bacterium Lactobacillus GG.
Gorbach is upfront about his financial ties to Culturelle.
"There is a conflict of interest here," he said. Still, more than 250 studies have shown LGG effective for gastrointestinal and allergy problems.
The National Center for Complementary and Alternative Medicine, part of the National Institutes of Health, is now funding a studing using an Italian product, VSL No. 3, for fatty liver disease at the Johns Hopkins Hospital.
The lead investigator on that study, Dr. Steven Solga, a gastroenterologist, said he believes probiotics may also prove useful for allergies, asthma, eczema, inflammatory bowel disease and other problems.
Probiotics are classified as dietary supplements, which are not approved for marketing by the Food and Drug Administration.
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