Everything gives you cancer: but good lifestyle choices will help you fight it off.

Imagine inviting 12 friends to a dinner party--six men and six women. Look around the room and consider this: sometime in the future, two of the women and three of the men will develop cancer.

Depressing as it seems, those are the odds we all must face, according to the American Cancer Society (ACS). Doctors diagnosed 1.3 million people with cancer in 2004, ACS statistics show, and about half of those patients did not survive. One piece of hopeful news comes from the National Cancer Institute, which argues that 80 percent of all cancers are linked to the environment (including diet and lifestyle choices like smoking). So if we can figure out what kinds of chemicals or behaviors are causing certain types of cancer, we can prevent them.

Cigarette smoking is the most obvious example. If we could persuade everyone to stop smoking, lung cancer rates would drop by 90 percent. That would make a significant dent in the problem because lung cancer causes more deaths in men and women than any other type of cancer. Cigarette smoking is a key risk factor for breast and pancreatic cancer as well.

Being overweight is another top cause of breast, prostate and colon cancer. Too much sun exposure--another lifestyle choice--also is at the top of the list of cancer causes. Then there's too much unprotected sex, which spreads Human Papillomavirus (HPV), a sexually transmitted disease that drives up cervical cancer rates. Failing to go for routine screenings, including pap tests, also leads to more cancer deaths.

Beyond that, it comes down to a combination of genetics and having the bad luck to run into something carcinogenic in the environment. Potential culprits include toxic chemicals, radon, asbestos, pesticides, magnetic fields, viruses and bacteria.

Ominous Signs

It's clear something has changed to make our environment more cancerous. Overall cancer incidence increased 48 percent between 1950 and 1990, according to the National Cancer Institute. That includes a 33 percent increase in childhood brain cancer, a 52 percent increase in breast cancer and a 134 percent increase in prostate cancer.

During that same time period, thousands of new chemicals flooded the market. Americans use 100,000 chemicals in everything from household cleaners and lawn chemicals to cosmetics and food preservatives, according to the National Institutes of Environmental Health Sciences (NIEHS). Manufacturers introduce 1,000 new chemicals each year.

We have so many chemicals in our country, government officials have trouble keeping up. Inevitably, some cancer-causing products will reach consumers. "You could ask, 'Are we doing enough? And are we doing it fast enough?'" says Paul Schulte, director of the education and information division for the National institute of Occupational Safety and Health (NIOSH). "We need to look for more systematic approaches that can screen larger numbers of chemicals."

Until those systems are in place, consumers must protect themselves. Below, we offer a list of common environmental causes of cancer. Health experts also share the latest prevention strategies.

Work-Related Exposure

Sadly, for many workers, the price of paying the bills for the family is getting sick with cancer. "On average, about four percent of all cancers are related to occupation," says Schulte. "But occupational cancer affects blue-collar workers more than white-collar workers." NIOSH estimates 40,000 American workers get cancer each year because of occupational exposure.

Certain industries have a higher cancer rate than others. Workers who make tires in rubber plants breathe 1,3-butadiene all day. Furniture makers and refinishers inhale a lot of benzene. Stone workers get lung cancer from silica dust. The plastic industry has more liver cancer. Agricultural workers who spray a lot of pesticides have a higher rate of non-Hodgkin's lymphoma and myeloma.

It's up to employers to prevent occupational cancer, Schulte says, and they're getting better at it. But workers need to make sure they have the right protective gear and wear it. It's also a good idea to notify your doctor if you work with known carcinogens.

Threats at Home

Meanwhile, some of the same threats people face in the workplace also are present--in lower levels--at home. Formaldehyde can leak from plywood furniture. Radon seeps from cracks in basement foundations. And lawn chemicals can waft over from a neighbor's yard. A nearby municipal incinerator could be clouding the skies with dioxin.

When it comes to lung cancer, people too often overlook some of the environmental causes, says Janice Nolen, director of national policy for the American Lung Association (ALA). For example, radon is the second-leading cause of lung cancer. It causes 23,000 deaths per year. Particulate pollution, from coal soot and diesel fuel, also causes lung cancer.

Nolen strongly advises homeowners to test for radon (or add special ventilation if building a new house). "You can't assume it's not in your area because it varies from house to house," she says.

Other precautions include staying inside on high particulate pollution days and making sure your child is not exposed to too much diesel pollution on school buses.

Estrogen Worries

Scientists are studying a relatively new class of chemicals called environmental estrogens. These compounds act like the body's natural hormones. They may be part of the rise in breast cancer. "Some breast tumor cells won't grow unless estrogen is there," says Suzanne Snedeker, a researcher with Cornell University's Breast Cancer and Environmental Research Factors program (BCERF).

Environmental estrogens bind to estrogen receptors and then send signals to breast cells to divide out of control and create a tumor. Estrogenic compounds include dioxin, many pesticides and plastic components, such as bisphenol A (BPA), some of which are released by microwaving containers. More recently, government researchers found evidence that estrogen from excreted birth control and hormone-replacement pills is getting into drinking water supplies. Snedeker suggests filtering drinking water to be safe.

Healthy Lifestyle

Exercising on a regular basis is almost as hard as quitting smoking for some. But obesity is a top cause of cancer, and keeping active sends oxygen to cells and prevents DNA damage. Health experts now say we need to do even more than a half hour three times a week. The right amount is one hour of moderate exercise per day, says Karen Collins, nutrition advisor for the American Institute for Cancer Research (MCR). "Moderate exercise" means taking an evening stroll, riding your bike to the post office or getting tough with the weeds in the backyard.

Everyone knows it's important to eat right, but most of us have no idea how to do it. Too much protein and saturated fat from animal sources causes the body to produce prostaglandins, which can stimulate abnormal cell division. Non-organic meat also may have synthetic hormones. For these reasons, health experts now say a predominately vegetarian diet is healthiest.

AICR offers a cookbook called The New American Plate. Instead of serving a huge slab of meat and potatoes with a tiny portion of peas, nutritionists say we should put two vegetables and a lot of whole grains on our plates. Meat or protein should take up no more than 1/3 of the plate.

Scientists at the University of Illinois' Functional Foods for Health program are zeroing in on natural compounds in certain foods that appear to prevent cancer. For example, lycopene, found in tomatoes, protects against prostate cancer. Garlic, blueberries, broccoli, fish and green tea are other foods with cancer-busting qualities.

Natural health guru Dr. Andrew Well suggests trying to eat a rainbow of fruits and vegetables each day to get the right variety of nutrients. Experts say five servings of fruits and veggies is good, but nine is even better.

Studies clearly show, with a healthy lifestyle, we can cut 30 to 40 percent of the cancers we face. Keith Singletary, a University of Illinois nutrition professor, says the odds tip in your favor if you get active, eat more veggies and lose those last few pounds. "Don't let the years go by," he says. "Go for it!" CONTACT: American Cancer Society, (800) ACS-2345, www.cancer.org; American Institute for Cancer Research (AICR), [phone], www.aicr.org.

MELISSA KNOPPER is a Colorado-based freelance writer.