Other risk factors – Lifestyle

Although carcinogens must cause a genetic mutation to a cell in order to kick-start the development of cancer, there are several other factors that can lead to the disease. Some of these factors are not carcinogens by definition, but they definitely do their part in carcinogenesis (the development of cancer).

Smoking is the leading cause of cancer. The American Cancer Society estimates that over 180,000 people will die from tobacco-related cancer in 2003. This is around one third of all cancer deaths. Besides generating certain cancer-causing chemicals in the smoke you inhale, it also causes different kinds of cellular oxidation including damage to cells' DNA. Smoking also reduces plasma levels of folic acid, which can debilitate the immune system and lead to cancer. Any way you look at it, the statistics speak for themselves – if you smoke, you have a much higher risk than if you do not. Although most people don't know it, smoking increases the risks of other cancers besides that of the lung, such as pancreatic, cervical, stomach and kidney cancers as well as myeloid leukaemia. Any amount of smoking increases your cancer risk dramatically. Significant second-hand smoke exposure can double the lung cancer risk for a non-smoker.

Diet is probably the most important risk factor. Diets high in fat are associated with increased cancer risk, especially of the prostate, colon, rectum and breast. In women, a high fat diet raises estrogen levels in the body, and high estrogen has been found to increase breast cancer risk. Diets low in fiber are associated with higher colon cancer risk (as well as other cancers). Diets high in sugar and simple carbohydrates are conducive to cancer. Diets high in antioxidants are associated with significantly reduced levels of cancer in general. There are many other dietary factors that influence your odds of developing cancer. We don't go into detail here because diet, and its relation to cancer risk, is what this book is mostly about and we talk about it extensively further on.

Excessive alcohol consumption has also been linked to increased cancer risk, especially of the liver, mouth, esophagus, stomach, colon, rectum, lung and breast. Those who drink and smoke have an even higher risk than the sum of the risks of either just smoking or just drinking excessively. Anything more than an average of two drinks per day is considered excessive.

Obesity is a cancer magnet. If you are overweight, and especially if you are obese, you run a much higher risk of cancer than "normal weight" people. If your excess body fat is centered around your abdominal area, you run an even higher risk. Researchers have found that up to 20 percent of male cancer deaths and 14 percent of female cancer deaths can be attributed to obesity. Excessive sugar and other simple carbohydrates lead to obesity.

Exercise is known to reduce cancer risk, so if you are one of those people that does not get exercise on a regular basis, you have a higher risk. The exact reasons that exercise reduces risk are unknown, but the statistics clearly demonstrate this. Aerobic exercise seems to be better than anaerobic exercise. One of the reasons exercise helps prevent cancer is that it usually keeps you from becoming obese, although it is believed there are other reasons.

Age of first period

It has been found that the earlier a woman gets her first period, the greater her risk is for cancers of the breast and cervix. A woman that had her period before the age of twelve is at significantly higher risk because she will have had higher estrogen levels in her body for a longer period of time. Higher estrogen levels have been associated with increased cancer risk for women.

Use of oral contraceptives and Hormone Replacement Therapy (HRT)

As mentioned above, higher estrogen levels can lead to cancer in women. Taking estrogen in the form of contraceptives or HRT raises the estrogen levels circulating through women's bodies, and this raises cancer risk, especially of the reproductive organs. See Appendix III for other risk factors for women.

In the introduction of the book we say that cancer is an immunodeficiency disease, yet we've been telling you above that it has other causes. This is not a contradiction, since it is a weak, undernourished immune system that allows these carcinogens that we come into contact with every day, or other conditions that we experience, to cause cancer. An immune system that is fortified by the proper amounts of the right nutrients will usually impede a cell's DNA from mutating or will kill the cell if its DNA changes.

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