Cancer, General

Cancer, General: Overview

This condition is included in the report of anyone who has (or has had) a known cancer, or who may be at greater risk of developing it.  It contains general recommendations that may be useful in dealing with a wide range of cancers.

Treatment and Prevention

There are many tactics that can be employed to reduce the risk of getting cancer.  When an increased risk of cancer is suggested, taking appropriate actions early on can lower this risk.

Prognosis

As a general principle, when weight loss has occurred or is significant prior to the start of chemotherapy, the survival rate is reduced.

The prognostic effect of weight loss prior to chemotherapy was analyzed using data from over 3,000 patients enrolled in 12 chemotherapy protocols.  The frequency of weight loss ranged from 31% for favorable non-Hodgkin's lymphoma to 87% for gastric cancer.  Median survival was significantly shorter in 9 protocols for the patients with weight loss compared to those without weight loss.

Signs, symptoms & indicators of Cancer, General:

Lab Values - Chemistries

Symptoms - Food - General

Symptoms - General

Symptoms - Liver / Gall Bladder

(Possible) enlarged liver is often a sign or symptom of Cancer, General (Possible) enlarged liver

The liver is a common site for metastatic cancer.

Symptoms - Metabolic

Conditions that suggest Cancer, General:

Lab Values

Metabolic

Ascites may suggest Cancer, General Ascites

Malignant ascites is typically due to advanced cancers of the organs in the abdominal cavity.  Examples include ovarian cancer in particular, as well as colon cancer, pancreatic cancer, stomach cancer, breast cancer, lymphoma, lung cancer, and cancer of the uterus or liver.

Skin-Hair-Nails

Night Sweats may suggest Cancer, General Night Sweats

Several malignancies can lead to night sweats.

Symptoms - Cancer

Tumors, Benign

Cysts may suggest Cancer, General Cysts

Cysts are very common and rarely turn into cancers, but it is important to make sure.  Cysts and tumors are completely different, but as cancerous cells grow out of control to form tumors, they may create spaces between tissues that fill with fluid or other material.

Tumors, Malignant

Bone Cancer often suggests Cancer, General Bone Cancer

Any type of cancer can spread to the bone, but the most common metastasizing cancers are breast, lung, kidney, thyroid, and prostate.

Risk factors for Cancer, General:

Addictions

Cigarette Smoke Damage often increases risk of Cancer, General Cigarette Smoke Damage

Cigarette smokers have total, overall cancer death rates twice that of nonsmokers.  The greater the number of cigarettes smoked, the greater the risk.

There is irrefutable evidence linking cigarette smoking and cancer of various sites.  The urine of cigarette smokers has been found to be strongly mutagenic in bacterial test systems.  There are at least 43 carcinogens described in cigarette smoke which include polyaromatic hydrocarbons, heterocyclic hydrocarbons, N-nitrosamines, aromatic amines, aldehydes, volatile carcinogens, inorganic compounds, and radioactive elements.

Cigarette smoke contains substances that act at every stage of cancer formation and growth.  Organs that have direct contact with smoke (lung, oral cavity and esophagus) are at the greatest risk of developing cancer.  As the substances delivered in cigarette smoke are absorbed and spread through the human body, smoking causes cancer at various distant sites.  For example, cigarette smoking is a risk factor for the development of cervical cancer.  Samples from the cervix of women smokers show components of tobacco smoke that contain mutagenic activity.

Family History

Hormones

Low Melatonin Level often increases risk of Cancer, General Low Melatonin Level

People with higher levels of melatonin might be less likely to develop cancer, and people with lower levels seem to be more likely to develop at least some forms of cancer.  At pharmacological levels (5-50mg), melatonin seems to be useful in fighting active cancers.  Neither of these effects are huge – a lack of melatonin does not always cause cancer, and a large dose of melatonin does not always cure cancer.  However, both effects seem large enough to be important.

Immunity

Metabolic

Problems Caused By Being Overweight may increase risk of Cancer, General Problems Caused By Being Overweight

Apart from excess stimulation by estrogen in breast and ovarian cancer, obese people are more prone to cancer, although it is still uncertain why.

Nutrients

Vitamin A Requirement may increase risk of Cancer, General Vitamin A Requirement

Analogues of vitamin A are known as retinoids.  Numerous studies have shown that retinoid deficiency enhances the risk of cancer in humans.  Retinoids are being used in humans to treat cancers (particularly skin, lung, bladder, cervical or breast) which involve epithelial tissues.  Vitamin A can be used to both treat and prevent cancers and there have been a number of studies showing beta carotene's protective effects against cancer.

Respiratory

Obstructive Sleep Apnea (OSA) may increase risk of Cancer, General Obstructive Sleep Apnea (OSA)

May, 2012: According to research to be publisherd in the American Journal of Respiratory and Critical Care Medicine, those affected by severe sleep disordered breathing (SDB) are 4.8 times more likely to develop cancer than those who are not.  Those with moderate SDB are at double the risk, and those with only slight SDB have a 10% increased risk of developing cancer.

The researchers from the University of Wisconsin-Madison looked at cancer rates in more than 1,500 people, in a study of sleep problems that has spanned 22 years.

Supplements and Medications

Counter-indicators
Frequent/regular aspirin use may decrease risk of Cancer, General Frequent/regular aspirin use

Several studies have demonstrated reduced mortality from various cancers among regular aspirin users.  A 2012 study showed a large reduction in death from esophageal, stomach and colon cancers among daily aspirin users, and a 12% reduction for other types of cancer.  [JNCI J Natl Cancer Inst (2012) 104 (16): pp1208-1217]

Counter-indicators

Symptoms - Cancer

Symptoms - Environment

Symptoms - Food - Beverages

(High) coffee consumption may increase risk of Cancer, General (High) coffee consumption

Studies linking coffee consumption with cancer are conflicting and inconclusive at this point, but there is a suggestion of a higher incidence of cancers of the pancreas, ovaries, bladder, and kidneys in coffee drinkers.

Symptoms - Food - General

Short-term low-carb dieting may increase risk of Cancer, General Long-term/short-term low-carb dieting or discontinued low-carb diet

The American Cancer Society has officially condemned diets high in animal grease, concluding that "a low carb diet can be a high-risk option when it comes to health." [American Cancer Society.  Weighing In on low carb Diets.  2004]

Severe/extreme calorie restriction may increase risk of Cancer, General Severe/extreme calorie restriction

Extreme calorie restriction can increase one's risk of developing serious health problems such as cancer.

Symptoms - Food - Preferences

Omnivorous diet may increase risk of Cancer, General (Partial) vegetarian diet or omnivorous diet

There has long been suspicion that components of meat and dairy were absorbed intact through the human digestive tract, triggering autoimmune disorders such as rheumatoid arthritis and childhood diabetes as our bodies try to fight off these foreign substances.  In October of 2003, researchers published new evidence that a substance found in lamb, pork, beef and dairy can build up in human tissues and may contribute to chronic disease.

Taking autopsy samples, traces of a molecule called NeuGc can be found in human tissues, particularly in human tumors (especially breast cancer).  Relatively high concentrations of anti-NeuGc antibodies can also be found in human blood.  This mystified researchers, as human beings can not produce this substance.  However, other animals can.  Maybe, the researchers proposed, human beings absorb it from eating other animals.

The researchers adopted a vegan diet for a few days to clear their system (no animal-derived ingredients in foods or drugs or shampoo), and then drank a glass of "diluted pig mucus".  Within days this invading meat molecule could be found oozing from their bodies, in their saliva, urine and hair clippings.

They speculate that this may why meat-eaters have such higher rates of cancer and heart disease compared to vegetarians.  They acknowledge it could just be the saturated fat in meat and dairy, but maybe it is also because of the incorporation of this foreign substance (plants do not produce NeuGc).  The researchers found it particularly interesting that vegetarian diets seem to improve rheumatoid arthritis.  Maybe this reactive alien molecule also triggers autoimmune diseases like hepatitis and arthritis.

This article was published in the proceedings of the most prestigious scientific body in the United States.  The researchers end their provocative article wondering what the long-term consequences might be of constantly challenging our immune systems in this way, and what the long-range implications are of having anti-Neu5Gc antibodies circulating throughout the bodies of meat-eaters and milk-drinkers.  [Proceedings of the National Academy of Sciences 100 (2003): p.12045]

Symptoms - Immune System

Significant history of cysts may increase risk of Cancer, General Significant history of cysts

Cysts are very common and rarely turn into cancers, but it is important to make sure.  Cysts and tumors are completely different, but as cancerous cells grow out of control to form tumors, they may create spaces between tissues that fill with fluid or other material.

Significant history of cysts may increase risk of Cancer, General Significant history of cysts

Although cysts rarely turn into cancers, they should be checked to make sure.  As tumors grow, they may create pockets in surrounding tissue that fill with fluid or other material.

Cancer, General suggests the following may be present:

Hormones

Immunity

Cancer, General can lead to:

Metabolic

Recommendations for Cancer, General:

Amino Acid / Protein

L-Arginine may help with Cancer, General L-Arginine

Clinical studies have shown improved immune function in cancer patients fed arginine.

Glutamine may help with Cancer, General Glutamine

Individuals with cancer who may be incapable of manufacturing their own supply of glutamine, may benefit from glutamine supplementats taken along with other amino acids.  Recommendation: 1 scoopful (3-4gm) mixed with water 3-4 times daily; swish in mouth and swallow.  Alternately 1,500-2,000mg in pills, 4 times a day.  All doses taken between meals.

Tyramine-containing Foods Avoidance may help with Cancer, General Tyramine-containing Foods Avoidance

Only those using hydrazine sulfate are required to avoid tyramine-containing foods.

Animal-based

Propolis may help with Cancer, General Propolis

Bee propolis, a sticky resin collected by bees from trees, is a COX-2 inhibitor, according to Dr. Gaynor.  Dr. Rao has found bee propolis very effective for cancer prevention in animals, noting "You can use it in lower doses than curcumin because it is highly absorbable." It is typically sold in 500mg capsules.

Botanical

Bindweed often helps with Cancer, General Bindweed

Bindweed inhibits new blood vessel development and thus restricts cancer growth.  A typical dose is four to six 250mg capsules per day.  Support for its use in cancer is currently limited to laboratory studies and personal experiences.

Herbal Combinations may help with Cancer, General Herbal Combinations

The essential ingredients of "C" Formula and "Y" Formula – CESSIAC(R) and YUCCALIVE(R) – include sheep sorrel, burdock root, schidigera yucca and fennel.  The results of this group of observations, conducted in China, showed that the combined use of "C" Formula and "Y" Formula had confirmed therapeutic effect on the treatment and prevention of tumors.  They could improve the immunologic function of the body and the overall health of the patient.  The herbs had no obvious toxic side-effects.  Information and study details can be found at the home page for Focus On Health.

Of the 39 cases in this study, 23 were tumor patients and 16 were secondary immunologic deficiency patients.  Among the tumor patients, three died of advanced metastatic carcinoma since they were already at a critical stage when starting the treatment.  There was one case of complete remission, 6 cases of partial remission and 13 cases of moderate remission and stabilized development.  The total remission rate was 30.4%.  The rate of moderate remission and stabilized development was 56.5% and the death rate 13%.  Of the 16 secondary immunologic deficiency cases, 5 were notably benefitted, 8 were moderately benefitted, and three did not benefit.

Notably, there were no toxic side-reactions as seen with other anticancer drugs, such as arrest of bone marrow, digestive tract reactions and baldness.  On the contrary, all patients in the study group had improvements in spirit, appetite, digestive function, physical strength and immunologic function of the body.  The herbs were also shown to be effective on hepatitis B, allergic rhinitis, pulmonary tuberculosis and coronary heart disease.  Therefore, the herbal combination was considered to be better than other antitumor drugs.

Shiitake Mushrooms may help with Cancer, General Shiitake Mushrooms

The antitumor and anticancer properties of mushrooms have been studied.  Shiitake (Lentinus edodes) and reishi (Ganoderma ludidum) have been found to have general anticancer and immune-stimulating activity [Gan To Kagaku Ryoho 1982;9(8): pp.1474-81].  Maitake (Grifolia frondosa) also contains immune-stimulating polysaccharides.  There are some combination mushroom products on the market to help prevent and treat different forms of cancer.

Kelp may help with Cancer, General Kelp

Kelp and seaweed are anticancer agents, rich in the mucilagenous alginates which, like most fibers, gums and mucilages, swell in the intestines and absorb liquid as well as toxins and heavy metals.  Alginates may also stimulate T-cell production and function since numerous other mucopolysaccharides have been shown to do this.  Japanese studies show regular consumption of kelp reduces breast cancer risk.  Kelp extracts have been highly successful in inhibiting laboratory cancer strains.

Turmeric may help with Cancer, General Turmeric

Curcumin, the ingredient that gives turmeric its yellow color and one of the best studied of the natural COX-2 inhibitors, has been shown to inhibit the development of cancer in animals.  Dr. Chintalapally V.  Rao, a scientist with the American Health Foundation in Valhalla, New York, has conducted extensive animal studies with curcumin and notes that while the new drugs "undermine the activity of the COX-2 enzyme, curcumin completely blocks formation of the enzyme itself."

The intriguing evidence of curcumin's anticancer effects in animal studies has prompted a clinical trial of the compound.  Dr. Steven Schiff at Rockefeller University in New York is assessing whether curcumin supplements (250mg twice a day) can inhibit the development of colon cancer in humans.

As most of the cancer-inducing chemicals in cigarette smoke are only carcinogenic during the period between activation in the liver by Phase I and final detoxification by Phase II, curcumin in the turmeric can help prevent the cancer-causing effects of tobacco.  Those exposed to smoke, aromatic hydrocarbons, and other environmental carcinogens will probably benefit from the frequent use of curry or turmeric.

Rosemary may help with Cancer, General Rosemary

Rosemary is a COX-2 inhibitor, and increases the activity of detoxification enzymes.  An extract of rosemary, called carnosol, has inhibited the development of both breast and skin tumors in animals.  Rosemary can be used as a seasoning or a tea: Use 1tsp dried leaves per cup of hot water; steep for 15 minutes.

Detoxification

Coffee Enema is highly recommended for Cancer, General Coffee Enema

Dr. Max Gerson pioneered the use of the coffee enema starting in the 1930s as part of a general detoxification regimen for cancer.  Dr. Gerson noted some remarkable effects of this procedure including patients no longer needing pain-killers once on the enemas.

Dr. Lee Wattenberg, MD was able to show that substances found in coffee – kahweol and cafestol palmitate – promote the activity of a key enzyme system, glutathione S-transferase.  This enzyme is responsible for neutralizing free radicals, harmful chemicals now commonly implicated in the initiation of cancer and needed for detoxification.  Consuming coffee orally does not produce the benefits experienced when it is taken as an enema.

When cells are challenged by poisons, oxygen deprivation, malnutrition or a physical trauma they lose potassium, take on sodium and chloride, and swell up with excess water.  This "tissue damage syndrome" makes it easier for cancerous cells to survive.  Cells normally have a preference for potassium over sodium but when a cell is damaged it begins to prefer sodium.

This craving results in a damaged ability of cells to repair themselves and to utilize energy.  Furthermore, damaged cells produce toxins.  Around tumors are zones of "wounded" but still non-malignant tissue, swollen with salt and water.  Dr. Gerson believed that cancer could not exist in normal metabolism.  He directed his efforts toward creating normal metabolism in the tissue surrounding a tumor.

Diet

Alcohol Consumption may help with Cancer, General Alcohol Consumption

Resveratrol is a potent COX-2 inhibitor produced in the skin of red grapes, where it protects against oxidation and fungal infections.  Resveratrol is found in grape juice and red wine; red Bordeaux and French Cabernets contain a particularly high concentration of the compound.  Resveratrol appears to help protect against cancer in at least three ways: It is anti-inflammatory, an antioxidant, and may prevent cancer cells from progressing to their next stage.  Supplements provide about 600mcg of resveratrol, the amount found in a glass of red wine.

Not recommended
Therapeutic Fasting is sometimes not recommended for Cancer, General Therapeutic Fasting

Extended fasting should be avoided by patients with a current known cancer who have experienced significant weight loss.  These patients tend to be malnourished already, and further nutrient restriction by fasting would make matters worse.

However, research at the University of Southern California published in June, 2014 showed that prolonged fasting reduces levels of a hormone that increases cancer risk and tumor growth.

Drug

Aspirin often helps with Cancer, General Aspirin

People who take aspirin daily have a 36% reduced likelihood of developing metastatic cancer, according to a meta-analysis published in 2012.

Conventional Drug Use often helps with Cancer, General Conventional Drug Use

COX-2 inhibitor drugs, so-called because they block an enzyme called cyclooxygenase-2 (COX-2), are used to treat pain and inflammation.  There is now compelling evidence that they may also protect against cancer.  Mitch Gaynor, MD, director of medical oncology at the Strang Cancer Prevention Center in New York, notes that suppressing COX-2 may be beneficial because "...the COX-2 enzyme helps make carcinogens much more active once they get into your body.  The enzyme also allows cancerous cells to grow new blood vessels."

There may be drug-free alternatives to the synthetic COX-2 inhibitors as close as your spice shelf.  Although they do not have as powerful an action, it appears that certain foods are natural inhibitors of the COX-2 enzyme.  By incorporating these foods in your diet, you can obtain some of the potential cancer-preventing benefits of the COX-2 inhibitors naturally.

Hydrazine Sulfate may help with Cancer, General Hydrazine Sulfate

Cachexia (wasting) in cancer patients is produced by the cancer cells' partial metabolism of glucose, which leaves lactic acid as a by-product.  The liver expends enormous amounts of the body's energy converting lactic acid back to glucose.  As the cancer grows (and puts out more and more lactic acid) this process is intensified, and the body weakens and wastes away.  Hydrazine sulfate works by blocking a liver enzyme that catalyzes the conversion of lactic acid into glucose.  This both stops the constant energy drain on the body and robs the tumor of a significant source of energy.

Hormone

Melatonin may help with Cancer, General Melatonin

Melatonin has been shown to inhibit several types of cancer, especially hormone-related cancers like breast cancer and prostate cancer.  This may be due to its ability to reduce the number of cellular estrogen receptors, which reduces the production of cell-multiplication factors.  The immune-modulating properties of melatonin seem to convey additional anti-cancer properties.  It has been shown to support the use of interleukin-2 in anti-cancer therapy, especially under conditions of controlled lighting.  Many animal studies have demonstrated an increase in tumor growth rates in animals whose pineal glands have been removed.

Various researchers report successes against solid tumors, colorectal cancer, non-small cell lung cancer, brain metastases, glioblastoma, estrogen receptor-negative breast cancer, prostate cancer, metastatic renal cancer and adenocarcinoma of the pancreas.  Furthermore, these effects seem to be substantial.

To select a typical example, people with solid tumors were given either just IL-2 (a regulator of the immune system), or IL-2 plus melatonin.  15% of the people receiving just IL-2 survived after one year, whereas 46% of the people also receiving melatonin survived.  One researcher reported no failures i.e.  instances in which melatonin did not have a positive effect.  It has been proposed that melatonin might be useful for treating the general ill health found in cancer.

Lab Tests/Rule-Outs

Bacteria / Pathogen Testing by PCR may help with Cancer, General Bacteria / Pathogen Testing by PCR

US Biotek lab offers a Infectious Agents in Cancer Panel (Blood or Tissue Biopsy) which tests for the presence of Helicobacter pylori, Hepatitis B, Human Papilloma Virus (6, 11, 16, 18) and Epstein-Barr Virus (EBV).

Oxygen / Oxidative Therapies

Physical Medicine

Massage may help with Cancer, General Massage

It has been found at the James Cancer Hospital and Research Institute in Columbus, Ohio that cancer patients suffer less pain and anxiety after receiving therapeutic massage.

Preventive measures against Cancer, General:

Botanical

Green Tea may help prevent Cancer, General Green Tea

Green tea can delay or prevent the occurrence of some cancers, but typically must be consumed in large quantities (up to 10 cups or more) daily to achieve this effect.  Extracts taken in pill form may be more convenient.

Diet

High/Increased Fiber Diet often prevents Cancer, General High/Increased Fiber Diet

The Canadian Cancer Society recommends a higher fiber and lower fat diet to help lower the risk of cancer, especially colon and rectal cancers.  Diets high in fiber are also rich in anti-cancer compounds such as anti-oxidants and phytochemicals found in fruits, vegetables and whole grains.

Increased Fruit/Vegetable Consumption often prevents Cancer, General Increased Fruit/Vegetable Consumption

Consumption of fruits is widely accepted as lowering the risk of most common cancers except prostate cancer.  Many doctors recommend that people wishing to reduce their risk of cancer eat several pieces of fruit and several portions of vegetables every day.  Optimal intakes remain unknown.

Increased Fish Consumption often prevents Cancer, General Increased Fish Consumption

Study subjects who ate two or more servings of fish weekly had a much lower risk for esophageal, stomach, colon, rectum, and pancreatic cancers than those who avoided fish.  In fact, the rates of these types of cancer were 30 to 50 percent lower among fish eaters.  High fish consumption was also associated with lower risks for cancers of the larynx (30 percent lower risk), endometrial cancer (20 percent lower risk), and ovarian cancer (30 percent lower risk).

Cabbage Family Vegetables often prevents Cancer, General Cabbage Family Vegetables

Cruciferous vegetables will reduce the risk of cancer in smokers, and most likely non-smokers as well.

Plant-Based Nutrition may help prevent Cancer, General Plant-Based Nutrition

"35 percent of cancer deaths may be related to diet." [The National Cancer Institute booklet "Diet, Nutrition, & Cancer Prevention: A Guide to Food Choices"]

Cancer rates for vegetarians are 25 to 50% below population averages, even after controlling for smoking, body mass index, and socioeconomic status.[1,2] Vegans show even better results.  One study found that people who include generous amounts of fruits and vegetables in their daily diets have lower rates of cancers of the lung, breast, colon, bladder, stomach, mouth, larynx, esophagus, pancreas, and cervix compared to people who avoid such foods.[3]

Fruits and vegetables contain antioxidant substances, such as vitamin C, vitamin E, and carotenoids, which protect cells against oxidative damage, which is related to cancer risk and other health problems.[4] The multitude of phytochemicals found in various fruits, vegetables, grains, legumes, and nuts are thought to protect against heart disease and cancer.[5]

  1. Chang-Claude J, Frentzel-Beyme R, Eilber U.  Mortality pattern of German vegetarians after 11 years of follow-up.  Epidemiology 1992;3:395-401
  2. Thorogood M, Mann J, Appleby P, McPherson K.  Risk of death from cancer and ischemic heart disease in meat and non-meat eaters.  Brit Med J 1994;308:1667-70
  3. Block G.  Epidemiologic evidence regarding vitamin C and cancer.  Am J Clin Nutr 1991;54:1310S-4S
  4. Jacob RA, Burri BJ.  Oxidative damage and defense.  Am J Clin Nutr 1996;63:985S-90S
  5. Craig WJ.  Phytochemicals: guardians of our health.  J Am Diet Assoc 1997;97:S199-S204

Environmental

Sunlight Exposure often prevents Cancer, General Sunlight Exposure

Staying out of the sun completely may increase your chances of developing cancer, say doctors.  For years, experts have advised people to cover up in the sun to protect themselves from skin cancer.  A letter in the British Medical Journal (November, 2003) from professor Cedric Garland of the University of California warns people against taking this advice to the extreme.  He says that a lack of sun can reduce levels of vitamin D, which may increase the risk of cancer.  Studies have suggested that vitamin D can protect against colon, breast, prostate and other cancers.

Hormone

Mineral

Nutrient

Lycopene often prevents Cancer, General Lycopene

A review of 72 studies [J Natl Cancer Inst 1999;91: pp.317-31] reported 57 associations between tomato intake or blood lycopene levels and decreased risk of cancer.  Of these associations, 35 were statistically significant.  The benefit was strongest for prostate, lung, and stomach cancers, although protective associations were also found for cancers of the pancreas, colon, rectum, esophagus, oral cavity, breast, and cervix.  Because the data were from observational studies, a cause-and-effect relationship cannot be firmly established.  However, the consistently lower risk of cancer associated with higher consumption of lycopene-containing tomatoes, provides a strong foundation for further research on lycopene.

One study found that for the 25% of people with the greatest tomato intake, the risk for cancers of the gastrointestinal tract was 30-60% lower, compared with those who ate fewer tomatoes.  These reduced risks were statistically significant.  [Int J Cancer 1994;59: pp.181-4]

Vitamins

Vitamin D often prevents Cancer, General Vitamin D

Evidence of vitamin D's protective effect against cancer is compelling.  For more than 50 years, documentation in medical literature suggests regular sun exposure is associated with substantial decreases in death rates from certain cancers and a decrease in overall cancer death rates.  Recent research suggests this is a causal relationship that acts through the body's vitamin D metabolic pathways.  For instance, some evidence points to a prostate, breast and colon cancer belt in the United States, which lies in northern latitudes under more cloud cover than other regions during the year.  Rates for these cancers are two to three times higher than in sunnier regions.

Dark-skinned people require more sun exposure to make vitamin D.  The thickness of the skin layer called the stratum corneum affects the absorption of UV radiation.  Dark human skin is thicker than white skin and thus transmits only about 40% of the UV rays for vitamin D production.  Darkly pigmented individuals who live in sunny equatorial climates experience a higher mortality (not incidence) rate from breast and prostate cancer when they move to geographic areas that are deprived of sunlight exposure in winter months.  The rate of increase varies, and researchers hesitate to quote figures because many migrant black populations also have poor nutrition and deficient health care that confound statistics somewhat.

Although excessive sun exposure may give rise to skin cancer, researchers as early as 1936 were aware that skin cancer patients have reduced rates of other cancers.  One researcher estimates moderate sunning would prevent 30,000 annual cancer deaths in the United States.

Vitamin D may also go beyond cancer prevention and provide tumor therapy.  Much has been made of pharmaceutical angiogenesis inhibitors – agents that help inhibit the growth of new, undesirable blood vessels that tumors require for nutrient supply and growth.  Laboratory tests have shown vitamin D to be a potent angiogenesis inhibitor.

Vitamin D also works at another stage of cancer development.  Tumor cells are young, immortal cells that never grow up, mature and die off.  Because vitamin D derivatives have been shown to promote normal cell growth and maturation, drug companies today are attempting to engineer patentable forms of vitamin D for anti-cancer therapy.

KEY

Weak or unproven link: may be a sign or symptom of; may suggest; may increase risk of; sometimes leads to
Weak or unproven link:
may be a sign or symptom of; may suggest; may increase risk of; sometimes leads to
Strong or generally accepted link: is often a sign or symptom of; often suggests; often increases risk of
Strong or generally accepted link:
is often a sign or symptom of; often suggests; often increases risk of
Definite or direct link: strongly suggests; increases risk of
Definite or direct link:
strongly suggests; increases risk of
Weakly counter-indicative: may decrease risk of
Weakly counter-indicative:
may decrease risk of
May be useful: may help with; may help prevent
May be useful:
may help with; may help prevent
Moderately useful: often helps with; often prevents
Moderately useful:
often helps with; often prevents
Very useful: is highly recommended for; usually prevents
Very useful:
is highly recommended for; usually prevents
Caution: is sometimes not recommended for
Caution:
is sometimes not recommended for