Most people assume that cancer is genetic and cannot be avoided. However, according to the American Cancer Society, healthy behaviors could prevent approximately half of cancer deaths. Below is a list of 10 lifestyle changes, all based on the latest research, which people can make to improve their odds of preventing cancer or catching it at its earliest, most curable stages.

-- Don't smoke or use any other tobacco products. Tobacco increases the risk for many cancers including those of the lung, bronchus, head and neck, colon, and bladder. If you smoke, stop. If you don't smoke, don't start. If you've tried to quit before, don't give up -- eventually something will work. Don't be afraid to ask for help from your physician, your family and friends, your employer, and even your insurance company. There are so many benefits to reducing smoking that many companies and insurance companies provide free help for quitting smoking.

-- Get screened for cancer regularly. Several tests can find cancer at a very early stage, sometimes even before a growth has turned cancerous. Finding cancer early can greatly increase your chance for a cure and reduce your risk of dying from the disease. Currently available cancer screening includes:

Colon: Starting at age 50, all people should have a colonoscopy (or even younger if at high risk). The frequency of colon screening depends on risk. A colonoscopy every 10 years is the norm for those with no personal or family history of colon cancer or high-risk polyps. Those at high risk may need more frequent testing. Acceptable alternatives for people who are not at high risk for colon cancer include flexible sigmoidoscopy, CT scanning and a test to check for hidden blood in the stool.

Breast: Starting at age 40, all women should get an annual mammogram (or even younger if at high risk) and a breast exam performed by a clinician. Some women may be eligible for a breast MRI and ultrasound as recommended by their physician.

Prostate: Starting at age 50 (or younger if at high risk), all men should have an annual physical exam (including a digital-rectal exam) and a blood test to check for blood levels of prostate-specific antigen, or PSA, which when elevated can be an indication of prostate cancer.

Cervix: Cervical-cancer screening (cervical sampling for Pap smear and human papillomavirus testing) should start as soon as a woman is sexually active and should continue throughout life with frequency depending on the woman's risk and age.

Skin: All adults should have a yearly skin exam by their primary care doctor. Those at high risk should have annual skin-cancer screening performed by a dermatologist. Persons at high risk for melanoma or other skin cancer should examine their own skin monthly.

-- Keep your alcohol consumption low. This means no more than two drinks per day for men and one drink per day for women. Alcohol use increases risk for several cancers including those of the breast, esophagus, colon, pancreas, and head and neck. Keeping your alcohol intake to the minimum daily level doesn't mean that you can "save up" all your drinks for a week and binge on Friday night with your weekly "allotment." This type of binge drinking is dangerous because it reduces your ability to make rational decisions, and it increases your risk of injury and of acute heart failure.

-- Protect your skin from the sun. Use sunscreen every time you go outdoors (preferably one with an SPF of 30 or higher that protects against both UVA and UVB rays). Keep covered with a broad hat and sunglasses, keep the amount of exposed skin to a minimum and limit time in the sun when it is the strongest (usually 10 a.m. to 4 p.m.) Remember that sun rays penetrate car and other windows, so you should use sunscreen any time you'll be getting sun exposure through a window. Never use a tanning bed, as they are as dangerous as sun exposure. If you want a tan without going outdoors, use a self-tanner, as such products do not cause skin cancer or other skin damage.

-- Keep a physically active lifestyle. Research suggests that exercising three to four hours per week at moderate or vigorous levels reduces the risk of several cancers by 30 percent to 50 percent. Many studies have shown that regular exercise lowers risk for breast and colon cancers, and studies now suggest that risks for endometrial and lung cancer may also be lower in people who exercise regularly. You don't need to be an athlete to get the benefit of exercise. Activities like brisk walking, biking, dancing, or any exercise that raises your heart rate and makes you sweat will be beneficial.

-- Keep your weight in the normal range for your height. That means keeping to a body mass index (BMI) of 25 or less. (You can calculate you BMI with online calculators). People who are overweight or obese have increased risk of developing several cancers including those of the colon, breast, pancreas, liver, kidney and endometrium, and perhaps leukemia and lymphoma. There is also evidence that men who are obese are more likely to develop a deadly form of prostate cancer if they develop the disease. Keep your weight steady; don't gain pounds over time. Try to stay within 5 to 10 pounds of what you weighed at age 18. The best way to avoid weight gain and avoid overweight or obesity is to eat a diet high in vegetables and fresh fruit and low in high-calorie foods like sugared drinks, refined carbohydrates and fatty foods.

-- Avoid taking menopausal hormone therapy. Menopausal hormone-replacement therapy increases risk for breast, endometrial and, possibly, ovarian cancer. If you have menopausal symptoms, try to handle them without hormone therapy including estrogens, progesterone, and testosterone. If you need to take hormones, limit your use to less than five years.

-- Consider taking medications for reducing cancer risk. There are several medications that have been tested and found effective for reducing risk for cancer. Anyone considering using such medications should talk with their doctor about the pros and cons of these medications given their risk for the disease. These include:

Breast: Tamoxifen and raloxifene both reduce the chance of developing breast cancer by half in women at increased risk for the disease. Women at increased risk include those over age 60, and women who have certain family histories of breast cancer or who have had certain types of benign breast disease.

Prostate: Finasteride has been shown to reduce the risk of developing prostate cancer by 25 percent. However, it increases risk for some types of advanced prostate cancer.

-- Avoid exposures to cancer-causing substances. Radiation exposures and some chemicals are known to cause cancer. Make sure that any physician who orders an X-ray for you, especially high-dose ones like CT scans, knows how many previous X-rays you have had. If it is not an emergency medical situation, ask whether there is an alternative examination that would work for you, such as ultrasound or MRI, which do not have radiation. Limiting X-ray exposure is especially important for children and teens. If you work in an industry or occupation where you are exposed to radiation or chemicals, be very careful to follow the regulations of your company and the U.S. Occupational Safety and Health Administration.

-- Eat a cancer-risk-reducing diet. The role of diet in cancer is far from established, but research suggests that a plant-based diet is associated with reduced risks for several cancers, especially for colon cancer. Some general dietary guidelines for reducing cancer risk are:

Keep your intake of red meat to a minimum. This means no more than 4 ounces of red meat per day on average. Four ounces of red meat is about as big as a deck of cards.

Avoid processed meats such as sausages and bologna. The chemicals used to process such meats have been found to cause several kinds of cancer.

Eat a variety of non-starchy vegetables and fruits every day. The National Cancer Institute recommends eating at least five servings of vegetables and fruit per day, but most experts on cancer and diet recommend at least double that amount. Experts further recommend that you eat a variety of brightly colored vegetables and fruits, as these contain the highest concentrations of vitamins. You can increase your intake of vegetables by putting them into your breakfast omelet, by snacking on carrots, and by mixing them into casseroles for dinner.

Minimize your intake of high-calorie foods such as sugared drinks, juices, desserts and candies, refined breads and bagels, and chips. By lowering intake of these high-calorie foods and increasing your intake of non-starchy vegetables, you will be better able to keep your weight to a normal level and avoid gaining weight.

Eat foods with high calcium and vitamin D levels such as fortified low- or nonfat milk and yogurt. If you don't get enough through your diet, you may want to take calcium and vitamin D supplements. Check with your doctor, who may want to check your blood level of vitamin D, because many Americans have been found to have a deficiency in this vitamin.

Fred Hutchinson Cancer Research Center
http://www.fhcrc.org