Fundamentals of Cancer Detection, Treatment, and Prevention. Surya K. De

same precaution involving the contribution of sugar to excess body fat applies.

      Regarding artificial sweeteners, researchers have done numerous studies of sugar substitutes such as saccharin (Sweet'N Low®, Sugar Twin®, and Necta Sweet®), cyclamate, aspartame (Equal®, NutraSweet®), acesulfame potassium (Sunett® and Sweet One®), sucralose (Splenda®), and neotame, and found no evidence that they cause cancer in humans. With the exception of cyclamate, all of these artificial sweeteners have been approved by the Food and Drug Administration for sale in the United States.

2.8 Role of Certain Foods and Drinks on Cancer

      If possible, the intake of these types of foods should be minimal.

      2.8.1 Processed Meat and Fish

According to the World Health Organization (WHO), processed meats like hot dog, ham, bacon, sausage, and some deli meats can cause cancer (Figure 2.5). Their carcinogenic effect is related to these foods being treated in some way to preserve or flavor them, such as by salting, curing, fermenting, or smoking.

Figure 2.5 Processed foods cause cancer.

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Salt‐cured fish, popular in China, is high in nitrates and nitrites, which have been shown to be carcinogens in animal testing and may cause cancer in humans. These chemical compounds can damage DNA, leading to cancers of the head and neck.

      Furthermore, the WHO has reported that any kind of red meat may be linked to an increased risk of colorectal cancer. There are studies suggesting red meat contributes to pancreatic and prostate cancers, although the evidence is not as conclusive.

      2.8.2 Alcohol

According to the American Institute for Cancer Research, there is now strong evidence that drinking alcohol increases the risk of developing several forms of cancer, including those of the mouth, pharynx, larynx, esophagus, liver, breast, stomach, and colorectum [19–35]. Drinking even small amounts regularly was shown to increase the risk of specific cancers, such as breast (Figure 2.6).

Figure 2.6 Drinking alcohol causes cancer.

      Source: LIGHTFIELD STUDIOS/Adobe Stock.

      For cancer prevention, it is suggested that alcohol consumption be eliminated. However, since alcohol has also been shown to have certain health benefits, including reducing heart disease and type 2 diabetes, guidelines have been modified to drinking two alcoholic beverages per day for men, and one per day for women.

Once in the body, ethanol is easily oxidized to acetaldehyde. DNA bases such as purine and pyrimidine are nucleophiles and react with acetaldehyde resulting in DNA damage inside cells. Alcohol and its byproducts damage the liver leading to inflammation and scarring (cirrhosis). Though liver cells try to repair the damage, yet they can end up with mistakes in their DNA, which can lead to cancer (Figure 2.7).

Figure 2.7 Bodily long‐term effects of alcohol consumption.

2.9 Role of Smoking or Tobacco Use on Cancer

Tobacco use is one of the leading causes of cancer and cancer mortality. People who smoke or use tobacco products, or who are regularly around environmental tobacco smoke known as “secondhand smoke,” have a proven, increased risk of developing cancer. Tobacco products contain more than 70 chemicals that damage DNA [36–72]. According to the Centers for Disease Control and Prevention (CDC), nonsmokers exposed to secondhand smoke at home or at work increase their risk of developing lung cancer by 20–30%.

Tobacco use has been linked to several types of cancer, including that of the lungs, larynx (voice box), mouth, esophagus, throat, bladder, kidney, liver, stomach, pancreas, colon and rectum, and cervix, as well as acute myeloid leukemia (Figure 2.8). Even people who use smokeless tobacco (snuff or chewing tobacco) are more susceptible than nontobacco users to cancers of the mouth, esophagus, and pancreas.

Figure 2.8 Negative bodily effects of smoking.

      There is no safe level of tobacco use, and it is recommended that anyone using any kind of tobacco product stop immediately. The tobacco industry has been known to minimize the risk, but obviously, an individual consumer's health is not their priority. Fortunately, those who quit smoking, regardless of their age and gender, increase their life expectancy substantially over people who continue to smoke. Furthermore, quitting smoking at the time of a cancer diagnosis significantly reduces an individual's risk of dying.

2.10 Role of Radiation on Cancer

Radiation of certain wavelengths, called ionizing radiation, has enough energy to damage cellular DNA and thereby cause cancer. Examples of ionizing radiation are radon, X‐rays, gamma rays, alpha particles, beta particles, and solar ultraviolet (UV) rays (discussed next). Although X‐rays are frequently used for diagnostic purposes in humans, the amount of exposure from them is not considered enough of the cancer risk to justify avoiding routine X‐ray screenings for potentially more life‐threatening conditions (Figure 2.9). The studies demonstrating the association between radiation and cancer tend to involve extremely high exposure levels, like those in a nuclear disaster, or the intense radiation sometimes needed to treat people who already have cancer. Nevertheless, the American Cancer Society cautions that “there is no threshold below which this kind of radiation is thought to be totally safe.”

Figure 2.9 Role of radiation on cancer.

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      Visible light and the energy from cell phones and electromagnetic fields are lower‐energy, nonionizing forms of radiation. They do not affect DNA and have not been linked to developing cancer.

2.11 Role of Sunlight and UV Radiation on Cancer

The sun, sunlamps, and tanning booths all produce UV radiation. Too much exposure to UV radiation damages the skin, resulting in early signs of aging and an increased risk of skin cancer (Figure 2.10). Although these effects are more common