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Dr. Rob Stuart of Charleston is one of 20 cyclists riding with Lance Armstrong from Los Angeles to Washington, DC.  This transcontinental ride takes place this month (October) first through the ninth.  Aside from the distance and the fact Lance is leading it, this tour is unusual because everyone of the cyclists is a cancer survivor and cancer care giver.  Dr. Stuart, for example, is an oncologist at the Hollings Cancer Center who has survived kidney cancer and is married to a leukemia survivor.  The purpose of the trip is to call attention to cancer and in particular the value of cancer victims to participate in clinical trials.  At the send off for Dr. Stuart, your columnist was told by Stuart training partner and Seabrooker, Cathy Nixon, that treating cancer is important and survivors like Lance Armstrong and Dr. Stuart show that we can treat cancer successfully, but how about preventing cancer with diet and lifestyle?

What is Prevention?
Prevention is defined as the reduction of cancer incidence and also a lowering of the mortality. This can be accomplished by avoiding cancer causing agents (called carcinogens) or altering the causing carcinogens’ interaction with the body.  Anything that increases a person’s chance of developing cancer is called a risk factor; anything that decreases a person’s chance of developing cancer is called a protective factor. Some of the risk factors for cancer can be avoided, but many can not.  Some of the things we do can protect us from cancer and some cannot.  There are medical interventions (chemoprevention) to successfully prevent certain cancers that involve taking medicines prescribed by your physician.  These are specific for some of the cancers and will not be discussed here.  However, prevention also consists of pursuing lifestyle or dietary practices that modify cancer-causing factors or genetic predispositions, and although this prevention, too, applies to certain cancers, it is generally believed that certain dietary and lifestyle actions may prevent many cancers.  An example of this is to NOT SMOKE.  Many of the cancers are associated with smoking and the one strongest preventive measure any one can take is not smoke and to avoid places where others do.   Most of what we know about cancer prevention comes from observational epidemiologic studies that show associations between modifiable life style factors or environmental exposures and specific cancers. This evidence is not as certain as when specific measures are tried in what we call “prospective randomized controlled trials designed to test whether interventions suggested by the epidemiologic studies, as well as leads based on laboratory research, result in reduced cancer incidence and mortality. Nevertheless, some things that you can do to prevent cancer are known and will be listed below.

Alcohol
When it comes to prevention, one thing we all have control over every day is what we drink and eat.  We make this decision and sometimes we exercise good judgment and other times we don’t.  There are some facts that relate to diet and nutrition and cancer that one needs to know to make good decisions about drinking and eating.    How about alcohol?  Alcohol consumption is related to some cancers.  It is associated with increased risk of oral, esophageal, breast, and other cancers.  Although apparently not a direct carcinogen, alcohol use increases the risk of liver cancer and also upper digestive cancer in smokers. The mechanism of its carcinogenic effect is not well understood but it is clear that alcohol interferes with body’s capacity to eliminate carcinogens such as those found in tobacco smoke, and may enhance mechanisms for formation of carcinogens found in tobacco smoke. In the breast and possibly the liver, its apparent carcinogenic effect may be mediated through increases in the level of estrogens in the blood. The same mechanism may be linked to a decrease in the risk of coronary heart disease. What about this evidence that wine moderate alcohol consumption is good for the heart?  That is true and most physicians advise that moderate alcohol consumption is OK, but cancer has been associated with excessive intake.  What one should not do is combine alcohol and smoking. 

Diet
Yes, we decide what we eat.  No there is not a lot of good scientific information on what to eat and not to eat to prevent cancer, but there is some.  Food and nutrient intake have been examined in relation to many types of cancer. Fruit and vegetable consumption have generally been found in epidemiologic studies to be associated with reduced risk for a number of different cancers; however, it is not currently known which specific components of fruits and vegetables are responsible for the observed associations or if healthy diets are simply associated with other beneficial interventions, e.g., exercise. Colon, breast and prostate cancers are associated with aging and although age is a risk factor the question before us is there information on diet and these cancers.  Among populations that consume a diet high in fat, protein, calories, alcohol, and meat (both red and white) and low in calcium and folate, colorectal cancer is more likely to develop than among populations that consume a low-fat, high-fiber diet. However, randomized controlled trials have found no reduction in risk of subsequent polyps of the colon in individuals who have had polyps resected taking dietary fiber supplements compared with those receiving much lower amounts of supplemental wheat bran fiber. On the other hand, there is evidence from at least 1 randomized controlled trial that calcium supplementation does modestly reduce risk of colon cancer recurrence. Consumption of red meat and inadequate folic acid intake have also been associated with increased risk of colon cancer. With regard to breast cancer, studies show that in populations that consume a high-fat diet, women are more likely to die of breast cancer than women in populations that consume a low-fat diet. It is not known if a diet low in fat will prevent breast cancer. Studies also show that certain vitamins may decrease a woman’s risk of breast cancer, especially premenopausal women at high risk.  Very little is known about diet and prostate cancer.  A diet high in fat, especially animal fat, may be associated with an increased risk of prostate cancer. Increased dietary intake of fruits and vegetables has been associated with a reduced risk of prostate cancer in some studies. 

Lifestyle
The last thing we make decision concerning is our lifestyle.  Will we be active or inactive?  Though understudied compared to other cancer prevention strategies and cardiovascular disease, it is known that physical activity may be associated with a lesser risk of several common forms of cancer, most notably colon and breast cancer. Physical inactivity (associated with increased risk of colon, breast, and possibly other cancers).  Exercise, especially in young women, may decrease hormone levels and contribute to a decreased breast cancer risk.  Persons having relatively high physical activity levels have been reported to have disease rates that are 25 to 50 percent lower than those among sedentary persons, making it exercise a sound preventive strategy.  Physical activity has effects on fat tissue, obesity and body fat distribution, as well as immunological, mechanical and hormonal effects, providing a range of possible mechanisms whereby physical activity may reduce cancer risk.  We all know that weight gain is a product of how many calories we burn compared to how many we take in.  Exercise and diet combine to control weight and one’s weight is a risk factor in cancer.  Being overweight is associated with colon, breast, endometrial, and possibly other cancers.  Postmenopausal weight gain, especially after natural menopause and/or after age 60, may increase breast cancer risk.  There is less information on other cancers.

 So as the cyclists cross this country raising our awareness of cancer, their trip reminds us of just how long the road is to discovering all that we can do to prevent cancer.  We know some things, we do not know much, but what we do know to do – eat, drink, and exercise while not smoking is likely to extend our time on our own life-trip.