It is often hard to discern from what we see and hear in the media exactly what course of action we should take to prevent cancer. We hear so much contradictory advice from scientists and other experts that it’s hard to know whom to believe. And as scientists learn more about cancer, their advice changes. Here’s a good example of this:

From Reuters, April 14, 2002:

Smoking may prevent breast cancer

Washington (Reuters) - Smoking, one of the biggest causes of cancer and heart disease, may actually help reduce the risk of breast cancer in some women, researchers said Tuesday.

The finding both surprised and dismayed the international team of scientists who did the study, but they said it may shed light on some of the mechanisms behind breast cancer. ‘We would hate it if women started smoking because of this study,’ Dr. Paul Kleiheus of the World Health Organization, which helped sponsor the study, said in a telephone interview.

The study found that smoking reduces by 50 percent the risk of developing breast cancer in women who have a rare genetic mutation that can lead to the disease. The mutation, in the genes BRCA1 and BRCA2, affects on average one in 250 women.

Kleiheus, who directs WHO’s International Agency for Research on Cancer, and colleagues were checking for a variety of lifestyle factors that could affect women with the mutation. It is known that just having a ‘bad’ gene does not guarantee disease–outside factors count, too.

So they were looking for which factors these might be, and surveyed more than 300 women in the United States and Canada who had BRCA1 or BRCA2 mutations. Half, 186 of them, had developed cancer and half had not.

They asked them about various factors, such as when they had children, what they ate–and whether they smoked.

The first thing that jumped out at the researchers was the clear link to smoking. ‘It was a surprise that smoking was the most striking result,’ Kleiheus said.

‘We are a little bit embarrassed,’ said Gilbert Lenoir, a biologist at the IARC, who also worked on the study, published in the Journal of the National Cancer Institute. ‘We are embarrassed because we feel that the tobacco industry may propagate this without being responsible.’

The researchers point out that many more women in industrialized countries such as the United States die from lung cancer than die from breast cancer.

The American Cancer Society predicts that 80,000 women will develop lung cancer this year and 67,000 will die from it, as compared to 43,500 deaths from breast cancer.

‘I think it wouldn’t be a good idea to take up the habit,’ Kleiheus said. ‘But on the other hand it is important for us, for the scientific community, and for the families that we have some hope for new research to try to come to some preventative measure.’

The researchers think there is probably a clear mechanism for explaining why smoking has this effect, and they hope that drugs can emulate the effect.

‘If you can inhibit the breast cancer risk in these women by smoking, then you can also do it by other ways,’ Kleiheus said. ‘We believe the most likely mechanism is a down-regulation of estrogen metabolism,’ he added. ‘This is a known effect of smoking.’

In other words, something in tobacco smoke slows down the breakdown of the female hormone estrogen in the body. Breast cancer is known to be linked to estrogen.

Kleiheus said perhaps drugs that interfere with estrogen could be developed to prevent breast cancer.

In fact, they have. Researchers this week said two drugs, the established cancer drug Tamoxifen and the osteoporosis drug Raloxifene, sold as Evista, can prevent breast cancer in women.

Both interfere with the way estrogen is used by the body.

Kleiheus said the drugs would have to be tested specifically on women with the BRCA1 and BRCA2 mutations to see if they also worked in this group.

‘Indeed they may be the drugs of choice, but we don’t know this at the moment because no study was done with these two agents in this high-risk population,’ he said.

The article above seems to suggest that smoking can actually prevent breast cancer in some women. Apparently cigarette smoke contains a substance that causes a reduction in the uptake of estrogen by breast cells. (This is how phytoestrogens or plant estrogens can reduce the growth of breast cancer cells.) With so much contradictory and confusing information out there, it is no wonder that most people just throw up their hands and go on eating and living the way they’ve always done.

In this chapter, we will present the latest information that scientists have on preventing cancer. Unfortunately, scientists and researchers don’t completely explain why these factors prevent cancer, but, in Chapter Eight, we’ll tell you why these factors prevent cancer from the perspective of our theory on the origin of cancer.


Most people have heard that free radicals cause cancer. But what exactly are free radicals? Oxygen free radicals are oxygen molecules that are deficient in electrons. They are generated as a by-product of oxygen-based metabolism. Ideally, oxygen and other molecules keep their electrons in pairs. Free radicals create electron pairs by stealing electrons from other molecules, damaging them in the process.

Electrons around an atom

Electrons whizzing around the nucleus of an atom

Antioxidants work by giving up their electrons to stabilize free radicals and prevent them from damaging DNA and other parts of the cell. The most potent antioxidants are vitamins, such as vitamins C and E, provitamins (or precursors to vitamin A, such as betacarotene), elements such as selenium and zinc, and enzymes such as superoxide dismutase and glutathione.

After decades of research, scientists have found many factors that seem to prevent cancer. Here are a few of those factors:


Vitamin A, Betacarotene

There have been recent studies that suggest taking betacarotene supplements actually causes a slight increase in mortality from lung cancer. Despite this finding, we still feel that taking higher doses of betacarotene is a good idea, but we recommend that it be taken in the form of vegetables and fruits, such as carrots, squash, tomatoes, alfalfa sprouts, kale, rhubarb, parsnips, yams, sweet potatoes, broccoli, and seaweed (nori and kombu, in Japanese).

Vitamin C 

Perhaps the most common vitamin deficiency in the U.S., the good news is that this vitamin is easily obtainable from citrus fruits, such as oranges, lemons, limes; and vegetables, such as peppers and tomatoes. The bad news is that we are becoming more and more deficient in this vitamin, as we consume more prepared, cooked, and fast foods. Vitamin C works to prevent free radical formation by absorbing the energy that creates free radicals. In a later chapter, we will explain why free radicals cause cancer.

Vitamin D

Vitamin D and calcium work together in our bodies to prevent skin cancer and colon cancer. Vitamin D is a protective vitamin that is naturally produced in the skin by sunlight. When our bodies are deprived of natural light, our skin produces less vitamin D and less calcium, resulting in more osteoporosis, especially in women, who have smaller and thinner bones. There is a constant give-and-take occurring in our bodies between the calcium in our bones and the calcium in our blood. Calcium regulates muscle contraction and is important for the proper functioning of our heart (hence, the use of calcium channel blockers in heart disease).

Vitamin E

Another important antioxidant is vitamin E. This vitamin is soluble in oil and prevents the spoiling or oxidation of oil- or fat-based substances in our bodies. It especially protects the lipids in cell membranes from free radical damage. Vitamin E enhances the functioning of the body’s immune system and prevents the formation of nitrosamines from nitrites in the stomach. In recent studies in Italy and Finland, it has been shown that higher vitamin E levels in the blood, along with higher levels of other vitamins, reduce the rates of breast cancer and other cancers.


Taxol, Tamoxifen (a cholesterol-lowering drug)

Cancer researchers discovered in the 1940s that certain breast cancer patients did better if they had their ovaries removed. From this, they deduced that certain types of breast cancer were affected by the levels of estrogen in the body.

In the 1960s, researchers discovered that breast cancer cells had receptors on their surfaces that attracted estrogen and induced the breast cancer cells to grow. Pharmaceutical companies then began developing drugs known as anti-estrogens to treat breast cancer. In the mid-1970s, they created tamoxifen—an anti-estrogen compound that acts like a false estrogen. It took until just recently, however, for these researchers to understand more about how tamoxifen and other similar drugs work, by acting like a fake “key” at receptor sites on breast cells and blocking real estrogen molecules from attaching to these sites. (In Chapter Eight, we’ll explain more about how and why tamoxifen works to treat and prevent cancer.)

Cis-platinum (Cisplatin), catalytic converters

Cisplatin binds to parts of DNA and interferes with the dividing of cells. This drug relies on the mechanism in the body to detect faulty cells that eventually causes these cells to die. Cisplatin is especially effective in the treatment of testicular cancer. In Chapter Six, we will discuss how our theory on the origin of cancer explains how and why cisplatin works against cancer.


Methotrexate belongs to a group of drugs known as antimetabolites. These drugs are used to treat cancers of the breast, head and neck, lung, blood, bone, lymph, and uterus (and are also effective against psoriasis and rheumatoid arthritis). This drug works by blocking the action of an enzyme known as dihydrofolate reductase in cells that are cancerous (or in skin cells with psoriasis). Unfortunately, other cells are affected by methotrexate, so serious side effects, such as hair loss, loss of appetite, blurred vision and dizziness can occur.

5-fluorouracil and similar drugs

The family of drugs represented by 5-fluorouracil works by interfering with the process of meiosis (DNA division) in the cell. Since some cancer cells are among those that divide most rapidly, these drugs work against these forms of cancer. Unfortunately, stomach cells and hair follicles are also among those cells that divide most rapidly, which is why cancer patients receiving these drugs usually become nauseous and lose their hair.



This green coloring matter in plants is essential to the production of carbohydrates by photosynthesis. Chlorophyll also works to soak up the energy of UV and ionizing radiation and prevent the formation of free radicals.

Illudin (mushrooms), diallyl disulphide (garlic, onions, chives) 

Mushrooms contain illudin, which has antitumor activity against certain kinds of leukemia cells and other cancer cells. Garlic, onion, chives and their relatives contain a chemical called diallyl disulphide, which can inhibit the growth of molds and bacteria. Diallyl disulphide has been found to be effective at preventing colorectal cancer.

Lactobacilli (miso soup, yogurt), Tuberculosis bacillus, E. coli

Some scientists have made the observation that some bacteria, such as E. coli, tuberculosis, and lactobacilli, seem to kill cancer cells or prevent cancer. We’ll explain why this is possible.

Phytoestrogens (plant estrogens)

Soy beans contain phytoestrogens that replace the body’s own estrogens, protecting against breast and ovarian cancers.


Broccoli and other cruciferous vegetables contain a substance called sulforaphane, which kills the Helicobacter pylori bacterium. This bacterium causes stomach ulcers and is believed to cause stomach cancer.


Natural (visible) light;    UV, and ionizing radiation (gamma rays, x-rays, cosmic rays)

Ultraviolet and ionizing radiation damages DNA and induces carcinogenesis. In experiments with fish DNA, DNA damaged by UV radiation can be repaired by exposure to visible light. In Chapter Seven, we will explain the significance of these findings.


Heat, hyperthermia 

It was believed at one time by some scientists that increasing the body temperature of cancer patients could slow down the progression of their disease. In a later chapter, we’ll explain why this phenomenon was observed and why it could possibly work, from the perspective of our theory on the origin of cancer. 


Many studies have shown that exercise seems to help slow the progression of cancer. We’ll provide an explanation for this, too, in a later chapter.



1) Free radicals are oxygen and other molecules that are deficient in electrons. They are thought to damage DNA and cause cancer. Vitamins, chlorophyll, selenium, and other substances prevent the formation of free radicals.

2) Vitamins are fat- or water-soluble organic substances obtained from plant and animal foods that are essential in small amounts for the normal growth and functioning of the body. As mentioned above, vitamins prevent the formation of free radicals and mitigate the damage they cause to DNA.

3) Taxol (tamoxifen) is a drug developed from the toxin of certain types of yew trees that kills tumor cells. 

4) Cis-platinum (cisplatin) is an anti-cancer agent whose development began in the 1960s by accident. During an experiment with bacteria in electrical fields, it was noticed that the bacteria stopped multiplying when something started leaching out of the electrodes. The substance was identified as platinum.

5) Methotrexate and 5-fluorouracil are antimetabolites that work by blocking enzymes that cancer cells need to live.

6) Alkylating agents are a family of anticancer drugs that interfere with the cell’s DNA and inhibit cancer cell growth.

7) Chlorophyll works to prevent cancer by reducing the formation of free radicals, especially by ultraviolet radiation.

8) Indoles, illudin, diallyl disulphide are found in cruciferous (cabbage-family) vegetables, mushrooms, and garlic and onions respectively. They have anti-cancer properties.

9) Lactobacilli are found in fermented foods, such as miso and yogurt, and are thought to prevent cancer.

10) Phytoestrogens block the action of regular estrogens. Estrogen can promote the growth of breast cancer cells.

11) Natural (visible) light can reverse the DNA damage caused by UV radiation.

12) Heat or hyperthermia was thought to have anti-cancer activity at one time.

13) Exercise seems to reduce the incidence of breast and other cancers.

Version 3.0


Next Chapter >>







© Copyright 2015. Phil Matsumoto. All rights reserved.


Last updated on 3//2/2015.