The incidence of some cancers has a clear hereditary influence, among them lung and breast cancer.
Cancer Nutritional Factors
Dietary and nutritional influences are thought to cause 60 percent of all cancers in women and 40 percent in men. Both cancer causing substances in the diet and lack of cancer inhibiting chemicals in foods play important roles.
High fat intake, including ingestion of large amounts of oxidized fats, those that are in the process of becoming rancid, are a source of increased free radicals, which promote DNA damage. The fat of animal meats contains hyper concentrated amounts of pesticides, which also contribute to cancers in humans.
In one review, for every additional intake of ten grams of fat per day, the cancer incidence rate increased 20 percent. A significant relationship between high polyunsaturated fat intake and the reduced incidence of malignant melanoma is apparent.
The highest intakes of sugar are associated with a fourfold excess risk for cancer of the gallbladder compared to the lowest intakes. Recent reports link higher sugar intakes to breast cancer as well. Cancer of the colon is also associated with high sugar intake and deficiency of folic acid.
Deficiency of fiber is directly related to increased risk of colon and rectal cancers. High levels of the phytoestrogens equol and enterolactone confer a lower risk for breast cancer. High concentrations of these are found in soy containing foods.
Epidemiological studies link excess iron to enhanced tumor growth and increased incidence of primary liver cancer and other malignancies.
Natural Carcinogenic Factors
Not all cancer causing substances are manmade. Cancerogenic psoralen compounds naturally occur in celery, parsnips, figs, and parsley. Aflatoxins occurring in seeds, nuts (especially peanuts), and grains, if any mold has accumulated, cause liver cancer. Cottonseed products contain a carcinogen.
Environmental Carcinogenic Factors
Environmental toxins (also referred to as xenobiotics) are highly suspect (e.g., air pollutants, pesticides, herbicides and fungicides, petrochemicals, and heavy metals). Exposure to petrochemicals, burned diesel fuel exhaust, and cyclic hydrocarbons result in free radical damage to DNA and lead to cancer formation.
A number of chemicals used in industry increase cancer risk, including heavy metals (lead, mercury; cadmium, arsenic), solvents (e.g., benzene), chrome and nickel ores, vinyi chloride, asbestos, chlorophenols, and bischloromethylether. Other chemical sources of cancer causing substances are defoliants (Agent Orange in Vietnam), coal tar derivatives in paints, food additives, and nitrosamines from nitrates in cosmetics and in food as preservatives.
Chronic use of hair dyes also contributes to the incidence of cancer. After combining with organic hydrocarbon residuals in polluted sources of water, chlorination of drinking water creates cancer causing chlorinated hydrocarbons, raising the all-cancer risk 15 percent, including 21 percent for bladder cancer and 38 percent for rectal cancer. Nations and tribes with low toxic chemical use and whole food diets have an astonishingly low incidence of cancers.
Radiation Cancer. Cancer risk is increased by any sources of gamma radiation, which affects nuclear plant workers, those living downwind from nuclear test sites, and those undergoing diagnostic and treatment exposure to X-rays. Children exposed to X-rays for shrinking adenoids and thymus glands and for treatment of ring worm of the scalp in the era 193 0 60 have a higher incidence of later leukemia and cancer of the thyroid.
Electromagnetic fields Cancer. Higher incidences of cancer of the head and neck appear to be present with exposure to electromagnetic fields, including use of electric razors. Years of exposure to indoor fluorescent lighting appear to significantly increase the risk of melanoma. Exposure to high tension electric power lines is related to risk of leukemias (especially in childhood).
Sun exposure cancer. Skin cancer incidence is greatly increased in white and Asian persons with long-term sun exposure, particularly with a history of deep tans and bad sunburns.
Drugs Cancer. Some drugs appear to enhance the risk for initiation and/or growth of cancers In rodents, the antidepressant drugs Prozac and aniitriptyline, given at doses equivalent to doses used in humans, stimulate the growth of deliberately injected melanomas. When a cancer-inducing chemical was given to a group of rats, 20 of 21 rats also given Prozac/amitriptyline developed breast cancers at 15 weeks, compared to only four of seven animals given placebos.
Antihistamines cancer have been shown to promote growth of cancers in laboratory animals. In mice, after injection of agents causing sarcoma and melanoma cancers, clear acceleration of sarcoma growth occurred in animals injected with Claritin and Hismanal (prescription antihistamines), and acceleration of melanomas occurred in animals injected with Atarax or Vistaril (prescription medicines for anxiety and itching). These drugs appear to accelerate growth of existing cancers.
Smoking and tobacco use significantly increase risks of cancer of the larynx, lung, breast, mouth, stomach, esophagus, pancreas, bladder, kidney, cervix, penis, lymphoma and leukemia (risks increased by 20 to 2,500 percent). Tn 1997 175,000 deaths were attributable to smoking and tobacco use. Passive smoking (nonsmokers living with a smoker) increases the risk of many of these same cancers. Smoking causes 85 percent of lung cancer and 35 percent of all cancers.
Lifelong drinkers of alcohol increase their risk of the following cancers several times: mouth, tongue, throat, esophagus, larynx, stomach, liver, colon, rectum (especially beer), pancreas, breast, and skin (malignant melanoma). Nineteen thousand deaths per year are attributable to alcohol use.
Weight. In men a 43-inch waist confers two and a half times the risk for colon cancer compared to men with a waist measure of 35 inches or less.
Lack of exercise and physical deconditioning play very significant promotional roles in a number of cancers.
Biomolecular Cancer Factors
Coenzyme Qi 0 tissue levels are considerably lower in breast biopsy specimens that turn out to be malignant compared to levels in specimens that turn out to be benign. Some cancers are clearly affected by hormones, such as prostate and breast cancer. In premenopauSal women, DHEA levels are about 10 percent lower in women who subsequently develop breast cancer.
Emotional Cancer Factors
Stress. Prospective studies show increases in cancer in persons under chronic, excessive, unmanaged stress and after acutely stressful events, such as the death of a spouse. In several studies, the way people cope with stress has been correlated with cancer related deaths and rate of cancer progression. In animals stress increases tumor development, including accelerated initiation, growth, and spread.
Depression. A large number of studies have noticed the consistent significant relationship of depression, helplessness, and hopelessness to the onset of various kinds of cancer. Depressed patients have a much lower incidence of successful bone marrow transplant survival than nondepressed patients. Patients who express their emotions in socially acceptable ways rather than repressing them also
consistently do better. Patients who believe that a lesser amount of adjustment will be necessary to cope with their disease also do better compared to those who believe the adjustment will be very high.
Cancer Social Factors
Dr. Caroline Thomas’s long term study of 1,500 medical students showed that the strongest psychological predictor of cancer over the next 25 years was the perception of lack of closeness with parents in childhood.