Lifestyle Changes:

Quitting Smoking

Quitting smoking improves lung function almost immediately. Some evidence suggests that the benefits for the lungs are even more significant for women who quit than for men. However, it can take 20 years or longer, particularly in heavy smokers, for the lungs to be restored to full health and the risk for lung cancer to be reduced as low as it is for nonsmokers. Quitting is extremely difficult. No one should be discouraged if they relapse. Everyone should keep trying to quit. With continued efforts, many people succeed.

The many methods of quitting smoking include counseling and support groups, nicotine patches, gums and sprays, and incremental reduction.

At this time perhaps the most effective method for quitting is a combination of the following:

• Nicotine replacement products that reduce withdrawal symptoms and cravings.
• The antidepressants bupropion (Zyban) or nortriptyline (Pamelor, Aventyl), which reduce emotional effects and cravings associated with withdrawal, and improve abstinence rates.
• Professional counseling or support organizations that may, in addition to medication, help people stop smoking.

[For more information, see In-Depth Report #41: Smoking.]

While people are in the process of quitting (and afterwards), they should maintain as healthy a lifestyle as possible.

Dietary Factors

The research on diet and cancer suggests that antioxidants in certain foods may protect against the DNA damage that can lead cells to turn cancerous. It's important to note that, although studies have suggested an association between these factors and cancer risk, no cause-and-effect has been proven. Still, it is always a good idea to eat a generally healthy diet.

Phytochemicals. Some data suggest that diets rich in fresh fruits and vegetables may protect against lung cancer in both smokers and nonsmokers. Studies have reported protection from specific plant chemicals (phytochemicals), such as the following:

• Isothiocyanates. These chemicals are found in cruciferous vegetables (broccoli, cauliflower, and Brussels sprouts). They may help block the effects of carcinogens in smoke, suppress tumor growth, and inhibit cancer growth-promoting steroid hormones.
• Flavonoids. Major sources are apples, grapefruit, onions, red wine, and tea. In one study on flavonoids, apple eaters had the lowest cancer risk, 68% less than those who ate fruit infrequently. In another study, those who ate more onions, apples, and white grapefruit had less than half the lung cancer risk than people who ate relatively small amounts of these foods. Flavonoids are also found in soybeans, berries, broccoli, carrots, citrus fruits, eggplant, peppers, squash, and tomatoes. Specific flavonoids in dark chocolate may help protect against lung cancer (but not other cancers).
• Lycopene. Lycopene is found in tomatoes, which have been associated with a lower risk for lung cancer. Cooking the tomatoes appears to increase the potency of lycopene.
• Cryptoxanthin. Some studies suggest that eating foods rich in cryptoxanthin, a yellow-orange pigment, reduces the risk for lung cancer. Foods with high amounts of cryptoxanthin include pumpkins, corn, papayas, red bell peppers, tangerines, oranges, and peaches. More research is needed in this area, however.
• Isoflavones. Found in soybeans and flaxseed, isoflavones behave like estrogen in some ways and not in others. Some evidence suggests the genistein (a type of isoflavone) in soy may have properties that protect against lung cancer.

Note: Studies on these chemicals are not consistent. It is unlikely that individual phytochemicals offer protection, but rather that the benefits come from a collection of vitamins and plant chemicals contained in fruits and vegetables. Fruit, especially, appears to be protective.

Fats and Oils. Some studies have indicated that diets high in animal fats increase the risk for lung cancer. Others have suggested some protection from cod liver oil, which contains omega-3 fatty acids (found in fatty fish), omega-6 fatty acids (found in flax and in soybean and canola oils), and monounsaturated oils (found in olive and canola oils). However, the ability of these substances to protect against lung cancer remains controversial, and quitting smoking remains the best advice.

Vitamin Supplements. Even in those who eat a healthful diet, smoking reduces the levels of a number of vitamins, importantly vitamin C. There is not enough evidence, however, to support any benefit from taking antioxidant supplements, including vitamins C, E, A, folate, or beta carotene.

In fact, evidence is now suggesting that high doses of vitamin C, vitamin E, and beta carotene supplements may have harmful effects. The strongest studies to date on the negative effects of antioxidant supplements have reported an increase in lung cancer and overall mortality rates among smokers who took beta carotene or vitamin E supplements. This is particularly important information for smokers, who may carry precancerous or cancerous cells for years before developing the disease. The best way to get healthy levels of important nutrients is by eating healthy foods.

Trace Element Supplements. Trace elements may be important in cancer risk and prevention.

Selenium appears to inhibit cell production and may have other anti-cancer properties. A few studies have reported some protection with selenium. However, one major analysis found that taking selenium only helps people who are deficient in the nutrient to begin with.

Zinc may prove to be more important than selenium. Some research suggests that zinc may help protect smokers by blocking cadmium. Smokers have higher levels of cadmium in their body, and there may be a link between cadmium and a higher risk for lung cancer. Some laboratory studies have indicated that zinc might help protect against tumor progression. There is no evidence that taking zinc supplements will reduce the risk for lung cancer, however.

Protecting the Home against Radon

People concerned about radon in their home or area can purchase a test approved by the Environmental Protection Agency. One way to remove radon is by installing a soil suction system. It should be noted, however, that home prevention measures rarely reduce radon levels to zero. Simply sleeping by an open window reduces the risk.

Nonsteroidal Anti-inflammatory Drugs (NSAIDs) and COX-2 Inhibitors (Coxibs)

Nonsteroidal anti-inflammatory drugs (NSAIDs) and COX-2 inhibitors (coxibs) both block cyclooxygenase (COX) enzymes. NSAIDs block COX-1 and 2, and coxibs selectively block COX-2. Evidence now strongly suggests that the COX-2 enzyme plays a role in blood vessel growth (angiogenesis) that can feed lung cancers.

NSAIDs. NSAIDs include aspirin, ibuprofen (Advil), and naproxen (such as Aleve, Naprosyn, Naprelan, amd Anaprox). These drugs inhibit COX-2, but they also target another COX enzyme. Studies are now reporting an association between regular use of aspirin or other NSAIDs and a reduced risk for non-small cell lung cancer.

COX-2 Inhibitors. The COX-2 inhibitors are more recent forms of NSAIDs. Only celecoxib (Celebrex) is still on the market. Because these medications target the COX-2 enzyme specifically, researchers are focusing on these drugs for a possible role in treating lung cancer and preventing its recurrence.

These medications are not currently recommended specifically for the purpose of reducing cancer risk.