Although the National Cancer Institute estimates that 1.2 million new cases of cancer were diagnosed in 1998, for the first time in history, the rate of breast cancer is down. Lung cancer rates are also decreasing. That’s because we now know there are valid ways to avoid cancer, slow its progress, or even cure it.

Here are the deadliest cancers and what we know about avoiding them.

Lung cancer. Lung cancer is the leading cause of cancer death among Americans; however, deaths from lung cancer are on the decline. To avoid lung cancer, do not smoke. More than 80 percent of lung cancers are related to smoking. If you live with someone who smokes, you are at risk from secondhand smoke, so help that person stop smoking.

Colorectal cancer. Colorectal cancer is the second leading cause of cancer death among Americans. But colorectal cancer is highly curable if it’s caught early. High-fat diets, low rates of activity and genetics are associated with an increased risk of these cancers. The typical Western-style diet, which is high in red and processed meats and refined sugars and grains and low in fresh fruits and vegetables, doubles the risk of colon cancer, according to a report in the American Journal of Epidemiology.

Breast cancer. Breast cancer is second only to lung cancer in cancer deaths among women. But 85 percent of all breast cancer patients—95 percent of those with localized cancer—remain alive five years after the cancer is detected. A woman’s risk of breast cancer is related to factors that affect the levels of hormones circulating in her body: age at first menstruation and menopause, number of pregnancies, breastfeeding, obesity and physical activity. Genetics also play a role.

Prostate cancer. Prostate cancer is the second leading cause of cancer death among American men. The cancer is most common in men over age 70. Appropriate therapy for most forms of slow-growing prostate cancer is still under investigation. Scientists know that prostate cancer is related to male hormones but are uncertain about the exact mechanism that causes the cancer. Since an increase in prostate cancer is associated with animal fats, red meats, and dairy products, saturated fat may be involved.

To reduce your risk of developing these cancers, don’t smoke, try to maintain a healthy weight, and get adequate exercise. In addition, heed the following advice.

• Eat a healthy diet. Eat a low-fat, high-fiber diet that is rich in fruits and vegetables. Studies consistently link a diet high in fruits and vegetables to a lower risk of cancer.
• Get screened. Regular screening for cancers of the breast, colon, and prostate can reduce mortality. Screening recommendations appear on page 13.
• Consider genetic testing. If breast, colorectal, or prostate cancer runs in your family, you may wish to consider genetic testing.
• Moderate your alcohol consumption. Compared with teetotalers, women who regularly have one drink a day raise their breast cancer risk by 11 percent. Those who regularly have more than two raise their risk by 40 percent. Alcohol also contributes to oral and esophageal cancers.
• Consider postmenopausal use of estrogen. When data gathered from 59,002 postmenopausal participants in the Nurses’ Health Study were analyzed, it was found that the risk of colorectal cancer was lower among women receiving hormone replacement therapy. But some studies indicate that HRT may increase the risk of breast cancer.
• Consider the benefits of drug therapy. Women at high risk of developing breast cancer may wish to consider taking tamoxifen. A recent study of 13,000 high-risk women found that those who used the drug, which is used to treat breast cancer, had a 45 percent reduced incidence of breast cancer. Tamoxifen did raise the risk of endometrial cancer, however. Another drug, raloxifene (Evista), which is used to reduce bone loss, has also shown protective benefits. When 7,705 women were studied, those taking raloxifene had a rate of breast cancer 66 percent lower than those taking a placebo (an inactive substance). They also had a 50 percent lower risk of endometrial cancer.